This document summarizes research on a low-rise concentrically braced frame building equipped with dissipative pin connections. It describes:
1) Experimental testing of a single-pin connection that dissipates energy through flexure of the pin, allowing braces to behave elastically.
2) Computer modeling using OpenSees of a one-story braced frame with these connections, validated against experimental results.
3) A comparative study of the braced frame's seismic response with and without dissipative connections.
Numerical modeling on behaviour of reinforced concrete exterior beam column j...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Seismic rehabilitation of beam column joint using gfrp sheets-2002Yara Mouna
The document summarizes a study that tested different rehabilitation techniques for improving the seismic performance of reinforced concrete beam-column joints. Three beam-column joints were tested: a control specimen and two specimens that were rehabilitated using glass fiber-reinforced polymer (GFRP) sheets. The control specimen failed in a brittle shear and bond failure mode, while the rehabilitated specimens exhibited a more ductile flexural failure of the beam. The rehabilitation techniques strengthened the joint shear capacity and prevented bond-slip failures of the beam reinforcement in the joint. A simple design methodology for the GFRP rehabilitation is proposed.
Finite Element Modeling On Behaviour Of Reinforced Concrete Beam Column Joint...IJERA Editor
Recent earthquakes have demonstrated that most of the reinforced concrete structures were severely damaged during earthquakes and they need major repair works. Beam column joints, being the lateral and vertical load resisting members in reinforced concrete structures are particularly vulnerable to failures during earthquakes. The existing reinforced concrete beam column joints which are not designed as per code IS13920:1993 must be strengthened since they do not meet the ductility requirements. The Finite element method (FEM) has become a staple for predicting and simulating the physical behaviour of complex engineering systems. The commercial finite element analysis (FEA) programs have gained common acceptance among engineers in industry and researchers. The details of the finite element analysis of beam column joints retrofitted with carbon fibre reinforced polymer sheets (CFRP) carried out using the package ANSYS are presented in this paper. Three exterior reinforced concrete beam column joint specimens were modelled using ANSYS package. The first specimen is the control specimen. This had reinforcement as per code IS 456:2000. The second specimen which is also the control specimen. This had reinforcement as per code IS 13920:1993. The third specimen had reinforcement as per code IS 456:2000 and was retrofitted with carbon fibre reinforced polymer (CFRP) sheets. During the analysis both the ends of column were hinged. Static load was applied at the free end of the cantilever beam up to a controlled load. The performance of the retrofitted beam column joint was compared with the control specimens and the results are presented in this paper.
Analysing The Composite Structure Of Riverted ,Hybrid And Bonded JointsIJERA Editor
Composite materials have been widely used as structural elements in aircraft structures due to their superior
properties. Aircraft structure is a huge assembly of skins, spars, frames etc. The structure consists of an
assembly of sub-structures properly arranged and connected to form a load transmission path. Such load
transmission path is achieved using joints. Joints constitute the weakest zones in the structure. Failure may occur
due to various reasons such as stress concentrations, excessive deflections etc. or a combination of these.
Therefore, to utilize the full potential of composite materials, the strength and stress distribution in the joints has
to be understood so that suitable configuration can be chosen for various applications
Castellated beam optimization by using Finite Element Analysis: A Review.theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Structural Analysis and Design of Castellated Beam in Fixed ActionAM Publications
The depth is the most important parameter which governs the sectional property of the section. For the serviceability moment of inertia plays very important role and moment of inertia of I-section is directly proportional to the third power of the depth. Research on cellular beams with circular web openings is very limited and is less developed than Cellular beams which may be attributed to the fact that cellular beams are more complicated to analyze due to their continuously changing section properties around the cell.
BTS 2016 - Composite SCL - Jiang Su_rev0.6Jiang Su
Utilising composite action to achieve lining thickness efficiency for sprayed concrete lined (SCL) tunnels.
The presentation discusses using composite action in SCL tunnels, where a primary lining is bonded to a secondary lining via a sprayed waterproofing membrane. Current design only considers the linings separately, but composite action allows load sharing and reduced thickness. The study uses numerical modeling to evaluate lining efficiency as the secondary lining thickness decreases from 300mm to 50mm. Results show the interface can withstand stresses and one-pass SCL is structurally possible, allowing more efficient tunnel design with thinner secondary linings. Further testing is needed to confirm long-term membrane behavior.
Behavior Of Castellated Composite Beam Subjected To Cyclic Loadsirjes
The purpose of this study is to determine the behavior of beam-column sub-assemblages castella
due to cyclic loading. Knowing these behaviors can if be analyzed the effectiveness of the concrete filler to
reduce the damage and improve capacity of beam castella. Test beam consists of beam castella fabricated from
normal beam (CB), castella beams with concrete filler between the flange (CCB) and normal beam (NB) as a
comparison. Results showed castella beam (CB) has the advantage to increase the flexural capacity and energy
absorption respectively 100.5% and 74.3%. Besides advantages, castella beam has the disadvantage that
lowering partial ductility and full ductility respectively 12.6 % and 18.1%, decrease resistance ratio 29.5 %
and accelerate the degradation rate of stiffness ratio 31.4%. By the concrete filler between the beam flange to
improve the ability of castella beam, then the beam castella have the ability to increase the flexural capacity of
184.78 %, 217.1% increase energy absorption, increase ductility partial and full ductility respectively 27.9 %
and 26 %, increases resistance ratio 52.5 % and slow the rate of degradation of the stiffness ratio 55.1 %..
Numerical modeling on behaviour of reinforced concrete exterior beam column j...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Seismic rehabilitation of beam column joint using gfrp sheets-2002Yara Mouna
The document summarizes a study that tested different rehabilitation techniques for improving the seismic performance of reinforced concrete beam-column joints. Three beam-column joints were tested: a control specimen and two specimens that were rehabilitated using glass fiber-reinforced polymer (GFRP) sheets. The control specimen failed in a brittle shear and bond failure mode, while the rehabilitated specimens exhibited a more ductile flexural failure of the beam. The rehabilitation techniques strengthened the joint shear capacity and prevented bond-slip failures of the beam reinforcement in the joint. A simple design methodology for the GFRP rehabilitation is proposed.
Finite Element Modeling On Behaviour Of Reinforced Concrete Beam Column Joint...IJERA Editor
Recent earthquakes have demonstrated that most of the reinforced concrete structures were severely damaged during earthquakes and they need major repair works. Beam column joints, being the lateral and vertical load resisting members in reinforced concrete structures are particularly vulnerable to failures during earthquakes. The existing reinforced concrete beam column joints which are not designed as per code IS13920:1993 must be strengthened since they do not meet the ductility requirements. The Finite element method (FEM) has become a staple for predicting and simulating the physical behaviour of complex engineering systems. The commercial finite element analysis (FEA) programs have gained common acceptance among engineers in industry and researchers. The details of the finite element analysis of beam column joints retrofitted with carbon fibre reinforced polymer sheets (CFRP) carried out using the package ANSYS are presented in this paper. Three exterior reinforced concrete beam column joint specimens were modelled using ANSYS package. The first specimen is the control specimen. This had reinforcement as per code IS 456:2000. The second specimen which is also the control specimen. This had reinforcement as per code IS 13920:1993. The third specimen had reinforcement as per code IS 456:2000 and was retrofitted with carbon fibre reinforced polymer (CFRP) sheets. During the analysis both the ends of column were hinged. Static load was applied at the free end of the cantilever beam up to a controlled load. The performance of the retrofitted beam column joint was compared with the control specimens and the results are presented in this paper.
Analysing The Composite Structure Of Riverted ,Hybrid And Bonded JointsIJERA Editor
Composite materials have been widely used as structural elements in aircraft structures due to their superior
properties. Aircraft structure is a huge assembly of skins, spars, frames etc. The structure consists of an
assembly of sub-structures properly arranged and connected to form a load transmission path. Such load
transmission path is achieved using joints. Joints constitute the weakest zones in the structure. Failure may occur
due to various reasons such as stress concentrations, excessive deflections etc. or a combination of these.
Therefore, to utilize the full potential of composite materials, the strength and stress distribution in the joints has
to be understood so that suitable configuration can be chosen for various applications
Castellated beam optimization by using Finite Element Analysis: A Review.theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Structural Analysis and Design of Castellated Beam in Fixed ActionAM Publications
The depth is the most important parameter which governs the sectional property of the section. For the serviceability moment of inertia plays very important role and moment of inertia of I-section is directly proportional to the third power of the depth. Research on cellular beams with circular web openings is very limited and is less developed than Cellular beams which may be attributed to the fact that cellular beams are more complicated to analyze due to their continuously changing section properties around the cell.
BTS 2016 - Composite SCL - Jiang Su_rev0.6Jiang Su
Utilising composite action to achieve lining thickness efficiency for sprayed concrete lined (SCL) tunnels.
The presentation discusses using composite action in SCL tunnels, where a primary lining is bonded to a secondary lining via a sprayed waterproofing membrane. Current design only considers the linings separately, but composite action allows load sharing and reduced thickness. The study uses numerical modeling to evaluate lining efficiency as the secondary lining thickness decreases from 300mm to 50mm. Results show the interface can withstand stresses and one-pass SCL is structurally possible, allowing more efficient tunnel design with thinner secondary linings. Further testing is needed to confirm long-term membrane behavior.
Behavior Of Castellated Composite Beam Subjected To Cyclic Loadsirjes
The purpose of this study is to determine the behavior of beam-column sub-assemblages castella
due to cyclic loading. Knowing these behaviors can if be analyzed the effectiveness of the concrete filler to
reduce the damage and improve capacity of beam castella. Test beam consists of beam castella fabricated from
normal beam (CB), castella beams with concrete filler between the flange (CCB) and normal beam (NB) as a
comparison. Results showed castella beam (CB) has the advantage to increase the flexural capacity and energy
absorption respectively 100.5% and 74.3%. Besides advantages, castella beam has the disadvantage that
lowering partial ductility and full ductility respectively 12.6 % and 18.1%, decrease resistance ratio 29.5 %
and accelerate the degradation rate of stiffness ratio 31.4%. By the concrete filler between the beam flange to
improve the ability of castella beam, then the beam castella have the ability to increase the flexural capacity of
184.78 %, 217.1% increase energy absorption, increase ductility partial and full ductility respectively 27.9 %
and 26 %, increases resistance ratio 52.5 % and slow the rate of degradation of the stiffness ratio 55.1 %..
An experimental investigation was conducted to investigate the behavior of ultra-high strength reactive concrete (RPC) columns before and after strengthening with carbon fiber reinforced polymer (CFRP) sheets jacketing under eccentric axi al load. Twelve columns were tested up to failure, strengthened and retested to examine strengthening efficiency and to evaluate the effects of variation of the concrete type (normal or RPC), presence of steel fibers and main steel reinforcement ratio. Experimental results showed that CFRP jacketing increases the ultimate failure load of strengthened columns up to 185%, highly stiffens them (reduces lateral displacements) and allow more ductile failure than the original columns. Also, inclusion of steel fibers in RPC columns increases failure loads up to 86%, prevents palling of the concrete cover and increase the ductility.
This paper involves an experimental investigation on the flexural behaviour of curved beams and comparison of its results with conventional beams. Curved beams of size 1200 x 150 x 100 mm with varying initial curvature as 4000mm, 2000mm and the concrete strength as M40 is considered. Various reinforcement are provided in the curved beams to predict which reinforcement detail would give more resistant over maximum loading. The material properties of cement, fine aggregate, coarse aggregate and the compressive strength of concrete cube were found out. A total of 12 specimens of curved beams were casted with various combination of reinforcement along with three control specimens. The beams are tested under two point loading both horizontally and vertically. The deflection and maximum moment carrying capacity are investigated to understand its strength. Also analytical modelling is done to determine the ultimate moment carrying capacity using Finite Element Software ABAQUS to compare with the experimental model.
NONLINEAR FINITE ELEMENT ANALYSIS FOR REINFORCED CONCRETE SLABS UNDER PUNCHIN...IAEME Publication
This paper presents an implementation of a three-dimensional nonlinear finite element model for evaluating the behavior of reinforced concrete slabs under centric load. The concrete was idealized by using eight-nodded solid elements. While flexural reinforcement and the shear were modeled as line elements, a perfected bond between solid elements and line elements was assumed. The nonlinear behavior of concrete in compression is simulated by an elasto-plastic work-hardening model, and in tension a suitable post-cracking model based on tension stiffening and shear retention models are employed. The steel was simulated using an elastic-full plastic model. The validity of the theoretical formulations and the program used was verified through comparison with available experimental data, and the agreement has proven to be good. A parametric study has been also carried out to investigate the influence of the slab thickness on column-slab connection response
Effect of Caging and Swimmer Bars on Flexural Response of RC Deep BeamsIJERA Editor
Beams with shear span to depth ratio (a/d) less than or equal to 2 are considered as deep beams. They have wide
applications in pile caps, water tanks, shear walls, corbels etc. Their strength is controlled by shear. Swimmer
bars are small inclined bars, whose both ends are bent horizontally and welded to both top and bottom flexural
reinforcement. Swimmer bars forming a plane crack interceptor system is effective in carrying shear. Also, a
reinforcement caging provided at the centre of a simply supported beam is supposed to enhance its flexural
capacity. In this study, an experimental investigation on the flexural response of deep beams reinforced with
caging and swimmer bars is done. Various parameters like ultimate load, deflection and failure modes of
different reinforcement patterns are studied.
Theoretical study for r.c. columns strengthened with gfrp with different main...Ahmed Ebid
DOI: 10.13140/2.1.3631.9041
It becomes a common practice to strength and repair reinforced concrete columns by wrapping them with GFRP sheets. The aim of this research is to develop a formula to describe the relation between the gain of strength of reinforced concrete square columns, their longitudinal reinforcement and number of warped layers of GFRP sheets. The research is based on simulating loading tests of a set of 12 reinforced concrete columns with different reinforcement ratios and different number of warped layers of GFRP sheets using ANSYS software. The outputs of the ANSYS models are verified using experimental tests results carried out by the author in earlier research. The results of the study are used to develop a proposed formula to correlate the axial capacity of the warped square RC column with its reinforcement ratio and the confining stress caused by the sheets. Values from both proposed formula design and formula of Egyptian Code of Practice (ECP) are compared with ANSYS outputs and experimental results. The final conclusion is that gained strength due to confining equals to (confining stress / Fcu)
This document summarizes an experimental study on using swimmer bars as shear reinforcement in reinforced concrete deep beams compared to vertical stirrups. Deep beams are defined as having a shear span to depth ratio of less than or equal to 2. Four different shear reinforcement patterns were tested: vertical stirrups (control), single swimmer bars, rectangular shaped swimmer bars, and rectangular shaped swimmer bars with cross bracings. Test results showed that beams with single swimmer bars had the highest failure load, increasing flexural strength by about 22% compared to the control beam. Beams with rectangular swimmer bars also increased strength but by a lesser amount. Crack patterns were diagonal shear cracks in all beams.
This document summarizes research on the buckling failure of compressed cellular steel members. Cellular members have large circular openings in their web which makes them more efficient in material use than plain members, but also alters their failure behavior when loaded axially and in bending. Through finite element analysis of various geometries, the authors developed a design approach to calculate the ultimate failure load based on the member's weak-axis flexural buckling capacity. Preliminary results found the approach provides acceptable but conservative estimates of failure load compared to simulations. Further study of residual stresses is still needed to fully validate the design approach.
Beam column joints in concrete framed structure have been identified as critical member for transferring forces and bending moments between beams and columns. The change of moments in beam and columns across the joint region, under loadings, induces high shear force and stresses as compared with other adjacent members. The shear failure caused is often brittle in nature which is not an acceptable structural performance. Retrofitting enhances the moment carrying capacity of joint. Often beam column joints need to be strengthened. Author proposes use of ferrocement for retrofitting as wrapping technique, cost effective alternative to costly FRP wrapping technique. In this present research study, modelling & comparison of Beam-Column joint with and without ferrocement jacket is carried out by finite element method using software ANSYS APDL. The comparison shows enhanced performance of the jacketed model over Non jacketed in terms of stresses, ultimate load carrying capacity.
Study of castellated beam using stiffeners a revieweSAT Journals
Abstract Now-a-days the use of castellated beam has been admired due to its beneficial functions like light in weight, easy to erect, economical and stronger. The castellated beam is manufactured from its parent solid I beam by cutting it in zigzag pattern and again joining it by welding, so that the depth of the beam increases. Hence, due to increase in depth of beam load carrying capacity of the parent I section is increased with same quantity of material. The increase in depth of castellated beam leads to web post buckling and lateral torsional buckling failure when these beams are subjected to loading. There are many other modes of failure like formation of flexure mechanism, lateral torsional buckling, and formation of vierendeel mechanism, rupture of the welded joint in a web post and shear buckling of a web post which needs to be taken care of. Study shows that use of stiffeners in the web portion of beam helps in minimizing these failures. Therefore, a detailed study in respect of number of stiffeners, size of stiffener and there locations in the web portion of castellated beam needs to be carried out. Hence, in the present paper an attempt has been made to review existing literature, concerned with strength of beam using stiffeners. The literature survey indicates that use of stiffeners in web portion of castellated beams helps in increasing the strength and also minimizing the deflection. Researchers have suggested using stiffener along the edges in order to reduce the stress concentration along openings.. Key Words: openings, castellated beam, cellular beam, stiffener, thickness.
The document summarizes research testing the effect of steel fiber volume fraction on the flexural strength of high-strength concrete beams. 25 beams were tested with steel fiber volumes from 0.5-4%. Testing showed flexural strength increased with higher fiber volumes. As fiber content increased, the failure mode transitioned from shear to flexure. Load-deflection curves showed higher maximum loads and deflections for beams with more fibers. In conclusion, adding steel fibers increases flexural strength of beams, especially at lower fiber volumes.
Optimum participation of beams and columns in lateral resistance of steel mom...Alexander Decker
This document discusses optimizing the participation of beams and columns in providing lateral resistance in steel moment frames. It presents research on five steel moment frames with varying numbers of stories and bays. The frames were modeled in ETABS2000 software and subjected to earthquake loads. The research aims to determine the optimum ratio of story drift to maximum allowable drift, based on the ratio of beam and column flexural stiffness. It found that increasing the flexural stiffness of columns, while keeping beam stiffness constant, reduced lateral displacement and brought story drift within allowable limits. Controlling the ratio of beam and column stiffness provides a way to optimize lateral frame resistance and displacement.
System shear connector jakarta digunakan sebagai aplikasi dalam konstruksi bangunan untuk menghasilkan kekuatan coran beton lebih kuat dan stabil sesuai dengan perhitungan engineering civil. Dalam hal ini ada 2 hal perhitungan kekuatan secara umum yaitu kekuatan kelengketan stud pada batang baja sesudah dilas. Dan yang kedua adalah kekuatan stud bolt yang digunakan.
This study investigated the compressive strength of reinforced concrete columns wrapped with different hybrid fiber reinforced polymer (FRP) configurations. Four 150x380mm concrete columns were tested: one unconfined control column and three wrapped with different combinations of glass, basalt, and jute FRP. The column wrapped with two layers each of basalt, glass, and jute FRP (CBGJ) achieved the highest compressive strength, reaching 1000kN and exceeding the unconfined column's strength by 25%. Analysis of the load-displacement and load-strain behaviors showed that the CBGJ wrapping configuration resulted in higher displacement and strain values compared to the other specimens. The results indicate that hybrid FRP wrapping can significantly
Effect of width and layers of GFRP strips on deflection of Reinforced Concret...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
IRJET- Study of Cold-Formed Steel Flexural Member Under Monotonic and Reverse...IRJET Journal
1) The document describes a study on the behavior of cold-formed steel build-up beams under monotonic and reversed cyclic loading. Beams made of open and closed steel sections were connected using various fastening methods and tested under different end conditions.
2) Tests were conducted to evaluate the strength, failure modes, hysteresis behavior, and effects of parameters like lipped sections. Beams with lipped sections showed higher strength and stiffness compared to plain beams.
3) Finite element analysis was also used to validate the experimental results. The strengths obtained from experiments agreed reasonably well with the finite element analysis.
Analysis of Behaviour of U-Girder Bridge DecksIDES Editor
The concept of U-shaped bridge girder is now being
increasingly adopted in urban metro rail projects and for
replacing old bridges where there is a constraint on vertical
clearance. These bridge decks are commonly designed in
practice using simplified methods that assume beam action of
the webs in the longitudinal direction and similar flexural
action of the deck slab in the transverse direction. However,
such assumptions can lead to errors. This paper attempts to
assess the extent of error in the simplified analysis, by
comparing the results with a more rigorous three-dimensional
finite element analysis (3DFEA). A typical prototype railway
bridge girder has been taken as a case study. The results of
the 3DFEA, in terms of load-deflection plots, have been
validated by field testing.
1) The document describes an experimental investigation of glass fibre reinforced plastic (GFRP) bridge deck panels subjected to static and fatigue loading.
2) Testing of prototype GFRP composite bridge deck panels was conducted under simulated wheel loads, with two rectangular patch loads applied symmetrically.
3) The results showed that under buckling criteria, panels failed at 123.6 kN with a deflection of 7.538mm, and under local shear criteria panels failed at 113.8 kN with a deflection of 4.057mm. Panels also resisted up to 5 million fatigue cycles.
#2 2006 improving seismic performance of concrete filled tube to base connec...jothi boominathan
The document summarizes an experimental study on improving the seismic performance of concrete-filled tube (CFT) column base connections. Seven CFT column specimens with varying embedded depths (0.5D, 1.0D, 1.5D) and stiffener configurations were tested under combined axial and lateral loads. It was observed that adding stiffeners to the embedded portion of the CFT columns increased the rigidity of the base connections and allowed the critical section to shift from the column bottom to the top of the foundation. Specimens with stiffeners developed their full strength even at an embedded depth of 0.5D, while an unstiffened specimen required a greater embedded depth of 1D to prevent premature concrete
MODELS FOR CONFINED CONCRETE COLUMNS WITH FIBER COMPOSITESIAEME Publication
Many studies have been done to find a convenient representation of physical behavior Fiber Reinforced Polymers for strengthening or retrofitted techniques which can enhance stress-strain performance of existing reinforced concrete structures. FRP composites are used for strengthening applications mainly due to the lightweight, high compressive strength, resistance to corrosion, speed and ease of application and formed on site. Conceptually, the s tress strain relation of concrete as a non-homogenous and nonlinear composite material is not unique that depends on the many variables.
The document discusses numerical modeling of dissipative pin devices used in brace-column connections in concentrically braced frames (CBF). It analyzes the behavior of single-pin and double-pin connection devices under monotonic and cyclic loading through theoretical models and an OpenSees beam model. The single-pin model is calibrated against experimental test data. The double-pin connection, with pins arranged in parallel or in-line configurations, is also studied through numerical modeling. The purpose of the pin connections is to preserve the elastic behavior of brace members while maintaining their buckling resistance by dissipating energy through the pins.
Construction of modern buildings requires many pipes and ducts in order to accommodate essential services such as air conditioning, electricity, telephone, and computer network. Web openings in concrete beams enable the installation of these services. A number of studies have been conducted with regards to reinforced concrete beams which contain web openings. The present paper aims to compile this state of the art work on the type of Reinforced Concrete (RC) beams with transverse web openings. Various design approaches and strengthening techniques are also presented.
An experimental investigation was conducted to investigate the behavior of ultra-high strength reactive concrete (RPC) columns before and after strengthening with carbon fiber reinforced polymer (CFRP) sheets jacketing under eccentric axi al load. Twelve columns were tested up to failure, strengthened and retested to examine strengthening efficiency and to evaluate the effects of variation of the concrete type (normal or RPC), presence of steel fibers and main steel reinforcement ratio. Experimental results showed that CFRP jacketing increases the ultimate failure load of strengthened columns up to 185%, highly stiffens them (reduces lateral displacements) and allow more ductile failure than the original columns. Also, inclusion of steel fibers in RPC columns increases failure loads up to 86%, prevents palling of the concrete cover and increase the ductility.
This paper involves an experimental investigation on the flexural behaviour of curved beams and comparison of its results with conventional beams. Curved beams of size 1200 x 150 x 100 mm with varying initial curvature as 4000mm, 2000mm and the concrete strength as M40 is considered. Various reinforcement are provided in the curved beams to predict which reinforcement detail would give more resistant over maximum loading. The material properties of cement, fine aggregate, coarse aggregate and the compressive strength of concrete cube were found out. A total of 12 specimens of curved beams were casted with various combination of reinforcement along with three control specimens. The beams are tested under two point loading both horizontally and vertically. The deflection and maximum moment carrying capacity are investigated to understand its strength. Also analytical modelling is done to determine the ultimate moment carrying capacity using Finite Element Software ABAQUS to compare with the experimental model.
NONLINEAR FINITE ELEMENT ANALYSIS FOR REINFORCED CONCRETE SLABS UNDER PUNCHIN...IAEME Publication
This paper presents an implementation of a three-dimensional nonlinear finite element model for evaluating the behavior of reinforced concrete slabs under centric load. The concrete was idealized by using eight-nodded solid elements. While flexural reinforcement and the shear were modeled as line elements, a perfected bond between solid elements and line elements was assumed. The nonlinear behavior of concrete in compression is simulated by an elasto-plastic work-hardening model, and in tension a suitable post-cracking model based on tension stiffening and shear retention models are employed. The steel was simulated using an elastic-full plastic model. The validity of the theoretical formulations and the program used was verified through comparison with available experimental data, and the agreement has proven to be good. A parametric study has been also carried out to investigate the influence of the slab thickness on column-slab connection response
Effect of Caging and Swimmer Bars on Flexural Response of RC Deep BeamsIJERA Editor
Beams with shear span to depth ratio (a/d) less than or equal to 2 are considered as deep beams. They have wide
applications in pile caps, water tanks, shear walls, corbels etc. Their strength is controlled by shear. Swimmer
bars are small inclined bars, whose both ends are bent horizontally and welded to both top and bottom flexural
reinforcement. Swimmer bars forming a plane crack interceptor system is effective in carrying shear. Also, a
reinforcement caging provided at the centre of a simply supported beam is supposed to enhance its flexural
capacity. In this study, an experimental investigation on the flexural response of deep beams reinforced with
caging and swimmer bars is done. Various parameters like ultimate load, deflection and failure modes of
different reinforcement patterns are studied.
Theoretical study for r.c. columns strengthened with gfrp with different main...Ahmed Ebid
DOI: 10.13140/2.1.3631.9041
It becomes a common practice to strength and repair reinforced concrete columns by wrapping them with GFRP sheets. The aim of this research is to develop a formula to describe the relation between the gain of strength of reinforced concrete square columns, their longitudinal reinforcement and number of warped layers of GFRP sheets. The research is based on simulating loading tests of a set of 12 reinforced concrete columns with different reinforcement ratios and different number of warped layers of GFRP sheets using ANSYS software. The outputs of the ANSYS models are verified using experimental tests results carried out by the author in earlier research. The results of the study are used to develop a proposed formula to correlate the axial capacity of the warped square RC column with its reinforcement ratio and the confining stress caused by the sheets. Values from both proposed formula design and formula of Egyptian Code of Practice (ECP) are compared with ANSYS outputs and experimental results. The final conclusion is that gained strength due to confining equals to (confining stress / Fcu)
This document summarizes an experimental study on using swimmer bars as shear reinforcement in reinforced concrete deep beams compared to vertical stirrups. Deep beams are defined as having a shear span to depth ratio of less than or equal to 2. Four different shear reinforcement patterns were tested: vertical stirrups (control), single swimmer bars, rectangular shaped swimmer bars, and rectangular shaped swimmer bars with cross bracings. Test results showed that beams with single swimmer bars had the highest failure load, increasing flexural strength by about 22% compared to the control beam. Beams with rectangular swimmer bars also increased strength but by a lesser amount. Crack patterns were diagonal shear cracks in all beams.
This document summarizes research on the buckling failure of compressed cellular steel members. Cellular members have large circular openings in their web which makes them more efficient in material use than plain members, but also alters their failure behavior when loaded axially and in bending. Through finite element analysis of various geometries, the authors developed a design approach to calculate the ultimate failure load based on the member's weak-axis flexural buckling capacity. Preliminary results found the approach provides acceptable but conservative estimates of failure load compared to simulations. Further study of residual stresses is still needed to fully validate the design approach.
Beam column joints in concrete framed structure have been identified as critical member for transferring forces and bending moments between beams and columns. The change of moments in beam and columns across the joint region, under loadings, induces high shear force and stresses as compared with other adjacent members. The shear failure caused is often brittle in nature which is not an acceptable structural performance. Retrofitting enhances the moment carrying capacity of joint. Often beam column joints need to be strengthened. Author proposes use of ferrocement for retrofitting as wrapping technique, cost effective alternative to costly FRP wrapping technique. In this present research study, modelling & comparison of Beam-Column joint with and without ferrocement jacket is carried out by finite element method using software ANSYS APDL. The comparison shows enhanced performance of the jacketed model over Non jacketed in terms of stresses, ultimate load carrying capacity.
Study of castellated beam using stiffeners a revieweSAT Journals
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The document summarizes research testing the effect of steel fiber volume fraction on the flexural strength of high-strength concrete beams. 25 beams were tested with steel fiber volumes from 0.5-4%. Testing showed flexural strength increased with higher fiber volumes. As fiber content increased, the failure mode transitioned from shear to flexure. Load-deflection curves showed higher maximum loads and deflections for beams with more fibers. In conclusion, adding steel fibers increases flexural strength of beams, especially at lower fiber volumes.
Optimum participation of beams and columns in lateral resistance of steel mom...Alexander Decker
This document discusses optimizing the participation of beams and columns in providing lateral resistance in steel moment frames. It presents research on five steel moment frames with varying numbers of stories and bays. The frames were modeled in ETABS2000 software and subjected to earthquake loads. The research aims to determine the optimum ratio of story drift to maximum allowable drift, based on the ratio of beam and column flexural stiffness. It found that increasing the flexural stiffness of columns, while keeping beam stiffness constant, reduced lateral displacement and brought story drift within allowable limits. Controlling the ratio of beam and column stiffness provides a way to optimize lateral frame resistance and displacement.
System shear connector jakarta digunakan sebagai aplikasi dalam konstruksi bangunan untuk menghasilkan kekuatan coran beton lebih kuat dan stabil sesuai dengan perhitungan engineering civil. Dalam hal ini ada 2 hal perhitungan kekuatan secara umum yaitu kekuatan kelengketan stud pada batang baja sesudah dilas. Dan yang kedua adalah kekuatan stud bolt yang digunakan.
This study investigated the compressive strength of reinforced concrete columns wrapped with different hybrid fiber reinforced polymer (FRP) configurations. Four 150x380mm concrete columns were tested: one unconfined control column and three wrapped with different combinations of glass, basalt, and jute FRP. The column wrapped with two layers each of basalt, glass, and jute FRP (CBGJ) achieved the highest compressive strength, reaching 1000kN and exceeding the unconfined column's strength by 25%. Analysis of the load-displacement and load-strain behaviors showed that the CBGJ wrapping configuration resulted in higher displacement and strain values compared to the other specimens. The results indicate that hybrid FRP wrapping can significantly
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IRJET- Study of Cold-Formed Steel Flexural Member Under Monotonic and Reverse...IRJET Journal
1) The document describes a study on the behavior of cold-formed steel build-up beams under monotonic and reversed cyclic loading. Beams made of open and closed steel sections were connected using various fastening methods and tested under different end conditions.
2) Tests were conducted to evaluate the strength, failure modes, hysteresis behavior, and effects of parameters like lipped sections. Beams with lipped sections showed higher strength and stiffness compared to plain beams.
3) Finite element analysis was also used to validate the experimental results. The strengths obtained from experiments agreed reasonably well with the finite element analysis.
Analysis of Behaviour of U-Girder Bridge DecksIDES Editor
The concept of U-shaped bridge girder is now being
increasingly adopted in urban metro rail projects and for
replacing old bridges where there is a constraint on vertical
clearance. These bridge decks are commonly designed in
practice using simplified methods that assume beam action of
the webs in the longitudinal direction and similar flexural
action of the deck slab in the transverse direction. However,
such assumptions can lead to errors. This paper attempts to
assess the extent of error in the simplified analysis, by
comparing the results with a more rigorous three-dimensional
finite element analysis (3DFEA). A typical prototype railway
bridge girder has been taken as a case study. The results of
the 3DFEA, in terms of load-deflection plots, have been
validated by field testing.
1) The document describes an experimental investigation of glass fibre reinforced plastic (GFRP) bridge deck panels subjected to static and fatigue loading.
2) Testing of prototype GFRP composite bridge deck panels was conducted under simulated wheel loads, with two rectangular patch loads applied symmetrically.
3) The results showed that under buckling criteria, panels failed at 123.6 kN with a deflection of 7.538mm, and under local shear criteria panels failed at 113.8 kN with a deflection of 4.057mm. Panels also resisted up to 5 million fatigue cycles.
#2 2006 improving seismic performance of concrete filled tube to base connec...jothi boominathan
The document summarizes an experimental study on improving the seismic performance of concrete-filled tube (CFT) column base connections. Seven CFT column specimens with varying embedded depths (0.5D, 1.0D, 1.5D) and stiffener configurations were tested under combined axial and lateral loads. It was observed that adding stiffeners to the embedded portion of the CFT columns increased the rigidity of the base connections and allowed the critical section to shift from the column bottom to the top of the foundation. Specimens with stiffeners developed their full strength even at an embedded depth of 0.5D, while an unstiffened specimen required a greater embedded depth of 1D to prevent premature concrete
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Many studies have been done to find a convenient representation of physical behavior Fiber Reinforced Polymers for strengthening or retrofitted techniques which can enhance stress-strain performance of existing reinforced concrete structures. FRP composites are used for strengthening applications mainly due to the lightweight, high compressive strength, resistance to corrosion, speed and ease of application and formed on site. Conceptually, the s tress strain relation of concrete as a non-homogenous and nonlinear composite material is not unique that depends on the many variables.
The document discusses numerical modeling of dissipative pin devices used in brace-column connections in concentrically braced frames (CBF). It analyzes the behavior of single-pin and double-pin connection devices under monotonic and cyclic loading through theoretical models and an OpenSees beam model. The single-pin model is calibrated against experimental test data. The double-pin connection, with pins arranged in parallel or in-line configurations, is also studied through numerical modeling. The purpose of the pin connections is to preserve the elastic behavior of brace members while maintaining their buckling resistance by dissipating energy through the pins.
Construction of modern buildings requires many pipes and ducts in order to accommodate essential services such as air conditioning, electricity, telephone, and computer network. Web openings in concrete beams enable the installation of these services. A number of studies have been conducted with regards to reinforced concrete beams which contain web openings. The present paper aims to compile this state of the art work on the type of Reinforced Concrete (RC) beams with transverse web openings. Various design approaches and strengthening techniques are also presented.
IRJET-Cyclic Response of Perforated Beam in Steel Column JointsIRJET Journal
This document summarizes a study on the cyclic response of perforated steel beams in column joints under finite element analysis. The study analyzed the effect of various web opening parameters on the energy dissipation capacity of beams with circular and elongated circular openings. A finite element model was validated against experimental data and then used to conduct a parametric study. The study found that energy dissipation increased as opening size and dimensions increased, with maximum dissipation achieved when the opening depth was 80% of the beam depth. Openings with an elongated circular shape oriented across the beam depth also dissipated more energy than other orientations. In general, beams with larger perforations performed better in dissipating energy during cyclic loading.
Effect of Perforation in Channel Section for Resistibility against Shear Buck...ijtsrd
1. The document presents a numerical study on the effect of perforations with different hole shapes (circular, elliptical, hexagonal, pentagonal, rhombus) on the shear buckling resistance of channel steel sections.
2. Finite element simulations were performed using ABAQUS to analyze the shear stress, deformation, reaction forces, eigen values/shear forces, and shear buckling coefficients in channel sections with different hole profiles.
3. The results showed that channel sections with hexagonal hole profiles experienced minimum shear stress compared to other hole shapes and sizes. Hexagonal hole profiles also resulted in less deformation. Overall, hexagonal and elliptical hole profiles provided better resistance to shear buckling compared to other
This document provides a major project synopsis presentation for an experimental and failure analysis of a CFRP-CFRP (carbon fiber reinforced plastic) single lap adhesive joint. The objectives are to fabricate single lap adhesive joint specimens with CFRP and Araldite AW106 adhesive, varying overlap length and adhesive thickness, and perform tensile testing and ANSYS analysis. The methodology involves a literature review, materials purchasing, specimen fabrication, testing, ANSYS analysis, results comparison, and conclusion. Dimensions, material properties, and validated ANSYS models are presented. The analysis shows maximum stresses at the overlap ends and agrees with reference results.
IRJET- A Review - Optimization of Castellated Beam with StiffenerIRJET Journal
This document provides a literature review on optimization of castellated beams with stiffeners. It discusses previous research that has studied the behavior and failure modes of castellated beams through experimental testing and finite element analysis. The review found that existing design codes provide empirical formulas for castellated beams but the complex behavior is not fully understood. The objective of the current study is to define the behavior of castellated beams with stiffeners and optimize the stiffener location, size, and thickness to improve performance.
IRJET- Fea & Experimental Analysis of Three Point Bending Test of Thin Walled...IRJET Journal
This document summarizes research on analyzing thin-walled circular structures filled with aluminum honeycomb that are subjected to three-point bending tests through finite element analysis and experimental testing. Specifically, the research involves:
1) Creating a 3D model of a circular specimen filled with aluminum honeycomb using CAD software and conducting experimental three-point bending tests on the specimen.
2) Analyzing the specimen through finite element analysis software and comparing the experimental and FEA results.
3) Drawing conclusions on the results and suggesting future work to further study circular thin-walled structures filled with honeycomb materials under three-point bending loads.
The document describes an extension to the brittle cracking concrete material model in ABAQUS. The extension adds nonlinear compressive behavior using a user subroutine. The extended model is validated by comparing it to the original brittle cracking model and damaged plasticity model under uniaxial loading. The extended model is also shown to capture strain rate effects observed in experiments. Finally, the extended model is used to simulate benchmark cases including a notched concrete beam, demonstrating its ability to model tensile failure of concrete structures.
This document summarizes research on modelling and designing dissipative connections for brace-to-column joints. The behaviour of single-pin and double-pin connection devices is emphasized through theoretical beam models and OpenSees models under monotonic and cyclic loading. The proposed models are calibrated against experimental test results from two specimens. The single-pin device consists of inner and outer plates with a pin running through, while the double-pin device has two pins. The models match the experimental hysteresis loops and energy dissipation, validating the numerical modelling approach.
This document describes a study analyzing the seismic performance of a 2-story concentrically braced frame (CBF) building with and without dissipative single-pin connections using OpenSees software. It first provides details on the design and modeling of the single-pin connection, which is intended to improve the seismic response of CBFs by allowing full development of brace compressive strength. It then describes the OpenSees model of the connection and calibration against experimental data. Finally, it outlines the numerical analysis conducted, including design of the CBF building based on Canadian standards and comparison of the seismic response of the building with and without pin connections.
Paper " STRUT-AND-TIE MODEL AND 3-D NONLINEAR FINITE ELEMENT ANALYSIS FOR THE...Waleed E. El-Demerdash
This document discusses the use of strut-and-tie modeling and 3D nonlinear finite element analysis to predict the behavior of reinforced concrete shallow and deep beams with openings. It presents the development of strut-and-tie models based on experimental results for selected beams. Finite element analysis using ANSYS is also employed for selected beams to complement the strut-and-tie model results. A parametric study investigates factors affecting beam behavior. Comparisons are made between finite element results, strut-and-tie model results, and experimental data.
The effective width in multi girder composite steel beams with web openingsIAEME Publication
This document summarizes a study on the effective width of multi-girder composite steel beams with web openings through finite element analysis. Several 3D models were developed to examine the effects of varying slab thickness, slab width, span length, and load type. The analysis found that thicker slabs experience less shear lag due to higher shear stiffness. Wider slabs and shorter spans also decreased shear lag effects. Different load types produced varying stress distributions across the slab width, affecting the effective width.
The document experimentally investigates the flexural behavior of cold-formed steel sections with triangular web corrugations. Three beam specimens with varying web depths of 200mm, 250mm, and 300mm were tested under two-point loading. The results show that flexural capacity increases with web depth. All beams failed by crushing of the top flange and lateral torsional buckling. Finite element analysis using ANSYS software correlated well with experimental results. The triangular web corrugations improved flexural strength compared to flat webs and prevented failure in the web or shear zones.
Utilization of steel in construction of high performance structures: A ReviewIRJET Journal
This document provides a literature review of research papers related to the analysis of steel structures using different alloys and metals in steel trusses. It summarizes several research papers that studied topics like cold-formed steel, steel beam-column connections, steel truss behavior, and comparisons of steel, concrete and cold-formed steel structures. The research papers used analytical and experimental methods to analyze structural behavior and load-carrying capacity. The results showed that cold-formed steel can provide economic and construction time benefits for buildings compared to other materials.
Study of Eccentrically Braced Outrigger Frame under Seismic ExitationIJTET Journal
Outrigger braced structures has efficient structural form consist of a central core, comprising braced frames with
horizontal cantilever ”outrigger” trusses or girders connecting the core to the outer column. When the structure is loaded
horizontally, vertical plane rotation of the core is restrained by the outriggers through tension in windward column and
compression in leeward column. The effective structural depth of the building is greatly increased, thus augmenting the lateral
stiffness of the building and reducing the lateral deflections and moments in core. In effect, the outriggers join the columns to the
core to make the structure behave as a partly composite cantilever. By providing eccentrically braced system in outrigger frame by
varying the size of links and analyzing it. Push over analysis is carried out by varying the link size using computer programs, Sap
2007 to understand their seismic performance. The ductile behavior of eccentrically braced frame is highly desirable for structures
subjected to strong ground motion. Maximum stiffness, strength, ductility and energy dissipation capacity are provided by
eccentrically braced frame. Studies were conducted on the use of outrigger frame for the high steel building subjected to
earthquake load. Braces are designed not to buckle, regardless of the severity of lateral loading on the frame. Thus eccentrically
braced frame ensures safety against collapse.
Experimental and FE Analysis of Funicular ShellsHARISH B A
Shells belong to the class of stressed skin
structures which, because of their geometry and small
flexural rigidity, tend to carry loads primarily by direct
stresses acting in their plane. Concrete funicular shells of
square ground plan, double curvature with 80 mm rise are
analysed for uniformly distributed load (One-way action).
Specimens of size 1080 mm x 1080 mm in plan with
rectangular edge beam of 50 mm x 40 mm are prepared
using cement concrete of grade M20 for which the mix
design is carried by Indian Standard method. The
precasting of the Concrete shallow funicular shell
specimens is carried by masonry mould method. The
specimens are prepared with thickness of 25 mm and 20
mm. The specimens are moist cured for 28 days before
testing. The uniformly distributed load over the shell
specimen is applied and the corresponding deflections,
strains are measured. The coordinates of funicular shells
are determined by developing a computer program. To
relate experimental results to theory, the finite element
technique (SAP 2000 Program) is utilized to analyse a
similar model in the elastic range. Finite element models
of funicular shells are developed by discretizing the shell
specimens into 20 elements along x direction and 20
elements along y direction. Behaviour of funicular shells
under uniformly distributed load is carried out.
Conclusions are made by comparing the experimental and
analytical results.
This document provides information on the design and behavior of eccentrically braced frames (EBFs). The key points are:
(1) EBFs resist lateral loads through a combination of frame and truss action, with inelastic behavior restricted to links.
(2) Links are designed to have high ductility and act as "fuses" that develop plastic hinges. Other members remain elastic.
(3) Link behavior depends on its length. Short links undergo shear yielding while long links undergo flexural yielding. Intermediate links experience both.
(4) Experimental tests show short links have the highest ductility capacity followed by intermediate then long links. Designs aim to match link
Non Linear Analysis of Composite Beam Slab Junction with Shear Connectors usi...inventionjournals
This document presents a non-linear finite element analysis of composite beam-slab junctions using ANSYS 16. It summarizes the research objectives, which include validating an ANSYS model against experimental test results and investigating the effects of shear connector type on the behavior of composite beams under cyclic loading. The study models a composite beam tested by Chapman and Balkrishnan using solid elements for concrete, link elements for rebar, and contact elements at the interface. Results show the model matches experimental data within 20% and that rectangular shear connectors are more effective at reducing deflection than circular connectors.
1. 2nd International Engineering Mechanics and Materials Specialty Conference
le 2
è
Congrès international de mécanique et des matériaux
Ottawa, Ontario
June 14-17, 2011 / 14 au 17 juin 2011
EM-02-1
Behaviour of a Low-Rise Concentrically Braced Frame Building with
and without Dissipative Pin Connections
L. Tirca, C. Caprarelli and N. Danila
Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Canada
Abstract: This paper presents the concept of elastic response of braced frame members equipped with
dissipative brace-to-column connections. In this study the single-pin connection was chosen to transfer
the axial force of the brace to the column. The computer simulation of this single-pin connection,
incorporated in a one-storey X-braced frame, was carried out using the OpenSees software and the
analytical results were validated against the experimental test results. In addition to the European loading
protocol, ECCS, considered in the experimental test, the AISC protocol used in the North American
practice was employed. A comparative study of a seismic response of one-storey concentrically braced
frame structure with and without dissipative connections was investigated through computer modeling.
The system was subjected to quasi-static loading only.
1. Introduction
Concentrically braced steel frame (CBF) buildings are widely used in Canada to withstand earthquake
loads. The current design philosophy consists of sizing braces to dissipate energy through yielding and/or
buckling, while all other braced frame members behave elastically. In this case, when failure or damage
occurs in the system, the replacement of braces becomes time consuming and labour costs can be fairly
high.
In order to devise a more efficient system, the concept of elastic response of braced frame members
equipped with dissipative brace-to-column connections is studied. Although this concept is not new, it has
not yet been promoted in seismic design. In addition, researchers have identified several brace failure
cases due to inadequate connection details. Thus, damages observed from seismic events indicate the
need to develop innovative structural systems with high stiffness, ductility and feasibility of repair.
The Canadian Design of Steel Structures standard (CAS/S16, 2009) states that for primary framing
members forming the seismic-force-resisting system of conventional constructions, the connections can
be “designed and detailed such that the governing failure mode is ductile when the member gross section
strength does not control the connection design loads”. Accordingly, the European seismic code
(Eurocode 8, 2004) states that for concentrically braced frames “the overstrength condition for
connections need not apply if the connections are designed to contribute significantly to the energy
dissipation capability” of the system. However the statement is not followed by specific design
requirements. Thus, the approach of dissipative connections was identified.
This paper describes the behaviour of a CBF with single-pin dissipative connections and the rationale
behind choosing it to transfer the axial force of the brace to the column member. More specifically, this
connection was developed and experimentally tested during the joint European research project, named
2. EM-02-2
the “Innovations for Earthquake Resistant Design” (INERD), (Plumier et al., 2005; Plumier and Doneux,
2006). It consists of two outer-plates welded or bolted to the flanges of the column member, two inner-
plates welded to the brace, and a pin running through the four plates. Under lateral loads, the pin exhibits
inelastic deformation and dissipates energy through bending. In this study, the computer modelling of the
single-pin connection incorporated in a one-storey X-braced frame, is carried out in the OpenSees
software environment and is validated against experimental tests results, obtained from the INERD
project. To analyse the behaviour of braced frames equipped with dissipative connections, the
OpenSees model was subjected to two quasi-static cyclic loading protocols: the ECCS displacement
loading protocol as developed by the aforementioned researchers and the AISC displacement protocol
(AISC, 2005).
Therefore, in this paper, the OpenSees model of a one-storey concentrically braced frame (CBF) with an
X-bracing configuration is developed, the computer model is validated against experimental results, and a
comparative study for the same CBF with and without dissipative connections is conducted.
2. Experimental Test Results
In the frame of the INERD project, it was concluded that the pin’s length, its cross-sectional shape, the
distance between the outer-plates, and the distance between inner-plates strongly influence the
connection behaviour, more specifically, its capacity to dissipate energy. A three-dimensional view of a
single-pin connection is illustrated in Figure 1. During the experimental program, different types of pin
cross-sections, such as round, rectangular and rectangular with rounded corners, have been investigated.
As per previous studies (Plumier et al., 2005; Vayas and Thanopoulos, 2005) and in agreement with the
experimental results, the behaviour of the pin is similar to the behaviour of a four-point loaded beam.
When considering the geometry of the connection as showed In Figure 2: two outer-plates welded or
bolted to the column, two inner-plates connected to the brace member and a pin running through the four
plates, it is seen that the pin is subjected to constant bending moment and dissipates energy in flexure.
From the experimental tests, it was concluded that a rectangular pin shape is able to dissipate a larger
amount of energy under small amplitude cycles than a rounded pin which performs better at larger
amplitude cycles.
Figure 1: 3-D view of the brace-to-column connection Figure 2: Detail of the single-pin connection
On the other hand, a rounded pin can resist larger forces due to reduced effects of torsion, while a
rectangular pin poses a larger moment of inertia. These results guided our decision to select the
rectangular cross-section with rounded corners for further investigation. Regarding the distance between
the inner-plates, it was concluded that the maximum energy is dissipated when a larger distance between
these plates is provided. However, this configuration depends on the size and depth of the column’s
cross-section which practically controls the length of the pin; therefore placing the inner-plates at the
3. EM-02-3
maximum allowable distance will optimize the functionality of the connection. The distance between the
inner-plates and the outer-plates, as considered in the selected experiment test, are shown in Fig. 2.
The behaviour of braces equipped with single-pin connections in an x-braced configuration is investigated
by studying the experimental test results of a full scale braced frame, tested at Politecnico di Milano in
Italy (Plumier et al., 2005) shown in Figure 3. As illustrated, the span and height of the frame is 3.4m and
3.0m respectively. The column cross-section is HE 240B and the beam cross-section is HE 200B. For
these cross-sections the geometrical properties were obtained from the ARBED property tables. The
beam is pin-connected to the column and both braces, made up of HE 160B profiles, are equipped with
dissipative single-pin connections at both ends. The pin’s length is 240mm, the distance between the
inner-plates is 50mm and the cross-sectional dimensions of the pin are 40 x 60mm. In addition, the
thickness of the inner plates is 15mm and the thickness of the outer-plates is 25mm. Experimental test
results demonstrated that the single-pin connection is able to dissipate energy under both quasi-static
and seismic loads, while maintaining braces in elastic range.
Figure 3: Test set up (according to Plumier et al., 2005)
Thus, in consequence to the introduction of dissipative connections in a braced frame allows braces to
behave elastically and avoids the asymmetrical braced frame response. As long as the buckling of braces
is prevented, the braced frame behaves symmetrical and in this stage, equal axial forces are developed
in both braces while it acts in tension or compression. The input energy focused in the brace-to-column
single-pin connections causes the pin to yield first. To maintain the elastic behaviour in the braces it is
recommended to design these members to develop 130% of their connection capacity in compression.
Braces are allowed to behave only in elastic range and the braced frame deformation is provided by the
bending deflection of the pin. Thus, when the brace acts in tension both pins deflect toward the brace and
when the brace acts in compression both pins deflect toward the columns.
3. Modelling and Design of Single-Pin Connections
The behaviour of the pin member, stated to behave as a four-point loaded beam, is studied using
OpenSees, under monotonic and cyclic displacement loading at large inelastic deformations.
Experimental test results showed that at the initial stage of loading the pin behaves as a simply supported
beam. Then, any increase in loads forced the pin to experience all stages of flexural stresses from the
initial yielding of the extreme cross-sectional fibers to the entire plastification of all fibers. During this
transitory stage, clamping forces are developed at the pin supports, which in practice is the pin-hole of the
outer-plate. Further, at subsequent loading steps, the pin behaves in the plastic range as a beam with
fixed supports. In order to validate the design approach of the pin, two methods are employed in
4. EM-02-4
research. First, the pin is designed as a beam using the OpenSees software, for which the scheme is
shown in Figure 4, and second the results are verified with a proposed static method known as the simple
beam model given in references (Plumier et al., 2005 and 2006; Vayas and Thanopoulos, 2005).
3.1 The OpenSees beam model
The OpenSees beam model, as shown in Figure 4, consists of eight nonlinear beam-column elements
and four integration points per element. The section used to describe the beam is made up of 60 fibers,
12 along the depth of the cross-section and 5 along the width of the cross section. The length of the beam
is the clear span between the outer-plates, therefore 240mm in the studied case. The material assigned
to the beam model is Steel02 labelled Giuffré-Menegotta-Pinto material with the same steel properties as
per the experimental test: Fy= 396MPa and Fu=558MPa. In the OpenSees beam model a very small strain
hardening value of 0.0005 was considered. In order to represent the behaviour of the pin, the 25 mm
thickness outer-plates acting as supports are modeled as rigid links. A calibrated Pinching4 material,
explained further on, is used to simulate the deformation of the pin in the outer-plates support. To allow
rotation between the beam member and the support (rigid link), a rotational spring formed of Pinching4
material is added at each beam end. If the axial force developed in the brace is P, then this value is
equally transferred through the two inner plates (P/2) to the pin.
Figure 4: OpenSees beam model
During the experimental test, the studied pin member was able to deflect 20mm before failure was
initiated. To validate the developed OpenSees beam model, the structure shown in Figure 4 was
subjected to an incremented displacement loading until the ultimate capacity of the pin was reached.
The two symmetrical loading points are marked in the aforementioned figure with P/2. The OpenSees
output is discussed in terms of force-displacement and force-bending moment curve shown in Figure 5,
respectively Figure 6. In addition the strain history distributed over the cross-sectional depth recorded at
the mid-length of the pin is illustrated in Figure 7. It is noted that the yielding strain value is εy = Fy/E =
0.002 and E, the modulus of elasticity, as provided by the experimental test is equal to 206GPa.
Thus, from Figure 7, the magnitude of the internal force which yields the extreme fibers of the pin is Py/2 =
108kN and its corresponding displacement and bending moment is δy = 0.35mm (Figure 5) respectively
My = 9.5kNm (Figure 6). These values match the theoretical relationship My = WyFy where Wy is the
elastic section modulus and the value of static deflection δy.
When the whole cross-section was plastified under the applied displacement loading, the strain in the
extreme fibers reached 10εy. The magnitude of the internal force applied to create the aforementioned
strain shown in Figure 7 is Pp/2 = 163kN and its corresponding displacement is 4mm. From Figure 6, the
bending moment developed under the Pp/2 force is Mp = 14.25kNm. Theoretically, this value corresponds
to Mp = WpFy, where Wp is the plastic section modulus. Thus, the corresponded applied force at yield, Py,
as well as the plastic force value, Pp was identified.
Once the internal force is greater than 163kN, the whole pin cross-section exhibits plastic behaviour. The
bending moment formed under the loading points is steadily increasing until the plastic moment is
reached, while negative bending moment starts to develop in the fixed pin-hole supports. At this stage,
as the applied force increases, the pin loses stiffness and the moment is transferred to the support
causing the formation of a new hinge before the complete failure of the connection occurs. As a
consequence, the moment at the point of application of the loads decreases and a moment at the support
5. EM-02-5
increases, causing the pin to behave as though it is clamped at its ends. As is shown in Figure 5, the
OpenSees beam model is able to identify the phenomenon of clamping after yielding is initiated in the pin.
Before failure was initiated, the displacement magnitude reached 20mm (Figure 5) and it matches the
experimental results.
Figure 5: OpenSees output; Force - Displacement; Figure 6: OpenSees output; Force – Moment
Figure 7: Strains distribution at the mid-length of the pin
3.2 Simple beam model
From both experimental tests and the OpenSees model, the same behavioural pattern was observed and
for the preliminary design purpose a theoretical method was devised. In this light, the pin can be
represented as a simply supported beam with a span equal to the distance between the outer-plates as
shown in Figure 8. The axial tension/compression force developed in the brace is transferred to the pin
through two-point loads located at the intersection of the inner-plates and the pin. As previously
mentioned, the maximum value of the force Py corresponding to the yielding moment My is Py = 2My/a or
Py/2 = My/a, where a = 87.5mm and is the distance between the outer-plate and the centroid of the inner-
plate. For the simply supported beam, the static deflection when yielding is experienced by the extreme
cross-sectional fibers is given by the following equation: δy = (My/6EI)aL(3 – 4a/L) where EI is the elastic
stiffness of the pin. Therefore, for the same rectangular pin 40x60 [mm
2
], My = 9.5kNm; Py/2 = 108kN and
δy = 0.35mm. From the mechanism of the simple beam model as shown in Figure 8 and by considering
6. EM-02-6
the small deflection theory, the deflection at strain hardening is δsh = δI = θa, where θ is the plastic rotation
and is given by the following equation: θ = κshlp. The value of curvature corresponding to the strain
hardening point κsh = 2εsh/h and the length of the plastic hinge, lp, can be approximated with the height of
the pin cross-section. In general, the average strain hardening value, εsh is considered εsh = 10εy which is
in agreement with Figure 7. By computing εy = 0.002 it results εsh = 0.02 and δsh = δI = θa = 2 x 0.02 x
87.5mm = 3.5mm ~ 4mm. This value is also correlated with the OpenSees beam model results shown in
Figure 5. The values of Pp = PI = 163kN and the afferent approximate displacement value δI = 4mm
correspond to the first segment of a tri-linear curve as shown in Figure 9.
Figure 8: Simple beam model and its plastic mechanism
In agreement with the plastic mechanism of the simple beam model, the ultimate load of the beam can be
derived from the bending moment diagram shown in Figure 8. According to the plastic beam mechanism
(Figure 8), by equating the work of the internal moments and the external forces we obtain (M1 + M2)θ =
Puδu/2 or Pu/2 = (M1 +M2)/a. From this last equation and the OpenSees beam model we can express the
value of Pu/2 as being approximately equal to the product of plastic modulus Wp and the ultimate strength
of steel: Pu/2 = Wpζu/a. It means that the plastic moment of the pin, based on the ultimate stress, is Mu =
Wpζu = 20kNm and Pu/2 = 230kN. This value also corresponds to the ultimate load obtained from the
OpenSees beam model as is shown in Figure 5.
Figure: 9 Tri-linear curve of the pin response
7. EM-02-7
The ultimate strain εu corresponding to the ultimate force PII = Pu/2 and deflection δII = δu, is about εu =
0.1, and at this stage the calculation involves the tangent modulus of elasticity, Et. For a strain of 0.1 the
corresponding plastic rotation is θ = 0.2 radians and the estimated ultimate plastic deflection is δu = δII =
1.15(0.2a) = 20mm which corresponds to the value given in the OpenSees beam model. Therefore, the
second segment characterised by the tangent modulus of elasticity, Et represents the behaviour of the pin
in its plastic range. Once the pin begins to exhibit plastic deformations, some clamping occurs at its ends.
The plastic mechanism of the pin consists of the formation of two plastic hinges under the point loads and
two at its supports.
3.3 Lateral drift
In a braced frame structure, the ultimate pin connection deformation influences the development of the
interstorey drift of the structure. In conformity with NBCC 2005 and for the ultimate limit state, this value is
limited to 2.5%hs where hs is the storey height. Therefore, the pin should be calibrated for the following
design criteria: i) strength: the compression capacity of the brace should be equal or larger than 130% the
capacity of the pin connection and ii) deformation: the distance between the outer and inner-plates
influences the deformation of the pin in bending and as a consequence the lateral deformation of the
frame. If we consider a brace equipped with dissipative pin connections at both ends, the diagonal line
will elongate with two times the inelastic transverse pin deformation, estimated at 2δII = 2[1.15(0.2a)] =
40mm. The horizontal projection of the deformation of the diagonal line with two pin connections is Δ =
2δII/ cosφ ~ 60mm for φ =41
0
(see Fig. 3). To ensure that the lateral drift is less than 2.5%hs, in this case
(h = 3m, a = 87.5mm), it is recommended that the connection deformation be less than 34.5mm and that
“a” be larger than 75mm [a > 34.5/(1.15x0.4); a > 75mm].
4. OpenSees Modelling of Braced Frames with and without Dissipative Connections
A one-storey braced frame with X-bracing configuration equipped with pin connections at each brace’s
end, as shown in Figure 3, was tested at Politecnico di Milano (Plumier et al., 2005) under the ECCS
displacement protocol and historical ground motions. To emulate the braced frame behaviour with single-
pin connections, the OpenSees model was developed and validated with the European experimental test
results.
The beams and columns were modeled using one beam-with-hinge element per member and the length
of the plastic hinge was set to be equal to the depth of the member. Each column cross-section was
defined as fiber section with 5 fibers along the flange width and 6 fibers along the depth of the web. The
columns were hinged at their base and pinned at the beam column connection. The beam section was
also defined as a fiber cross-section with again 5 fibers in the flange and 6 fibers in the web. The beam
was connected to the column with a zero-length rotational spring, C1. The x and y displacements of the
beam end nodes were slaved to those of the column end nodes. The spring in between the two nodes,
was set to work in rotation and exhibited almost no stiffness. This allowed modelling the conventional
shear connections found in concentrically braced frames. Each of the four brace segments were modeled
with 8 nonlinear beam-columns elements and 4 integration points per element. For the modeling of the X-
bracing configuration as shown in Figure 10, the tension brace was defined to work as one element using
16 sub-elements and the compression brace was designed as two half braces connected to the tension
brace by very stiff rotational springs, C4. The purpose of choosing the non-linear beam-column element
for braces was to ensure spreading of plasticity along the brace length when buckling occurred. The initial
camber set to each brace element was Lbrace/800. The cross-section of each brace was defined with 5
fibers along the flange width and 6 fibers along the depth of the web. A section aggregator was used to
assign a torsional stiffness to each braces sub-element’s cross-section.
In order to connect the braces to the columns, four rigid links were used. These rigid links were defined
as elastic beam-columns. The rigid links experience no deformations and therefore no plasticity is formed
in them and the linear beam-column element sufficed as an element choice. These rigid links represent
the part of the brace, or brace connectors (outer-plates) that are rigidly fastened to the column. The end
node of the brace was connected to the end node of its respective rigid link. A zero-length spring was
8. EM-02-8
inserted between the two nodes. The propertied of these springs C2 and C3 were set for two different
situations, one was to model a gusset plate and the other was to model the single-pin connection. In the
case of a gusset plate, stiffer properties were set in order to imitate its rigid behaviour. All of the
aforementioned members were modelled with the Steel02 Giuffré-Menegotta-Pinto material. This material
is represented by a force-deformation relationship and it exhibits some isotropic strain hardening in both
tension and compression.
The pin connection, represented by zero-length elements deforming in x and y translations, was defined
using the Pinching4 material. This material represents a pinched force-deformation response. The
pinching that is exhibited is the loss of resistance during unloading of the pin in tension and compression
right before reloading begins. In order to calibrate the material, the experimental results described in the
reference: Plumier et al., 2005, were used. As shown below in Figure 11, a skeleton curve was built to
encompass the total force deformation shape of the experimental testing. The three points defined in the
skeleton curve represent the tri-linear curve of the pin stiffness. The first slope would define the elastic
stiffness of the pin while the second slope defines the plastic stiffness and the third represents some
overstrength of material. The fourth point, which forms a fourth slope, is used to represent the returning or
unloading stiffness of the pin connection. The next step would be to define the pinched shape of the
curve. This is done by specifying three floating point values in tension and three floating point values in
compression. The first floating point value, both in tension and compression is defined by the ratio of the
deformation at the point of reloading to the total hysteretic deformation demand. The second floating point
value, again in both tension and compression, is the ratio of the force at the point of reloading to the force
corresponding to the total hysteretic deformation demand. The third floating point value is a ratio of the
strength developed upon unloading to the maximum strength developed in the monotonic loading stage.
Figure 10: OpenSees braced frame model Figure 11: Pinching material calibration
The braced frame response was investigated under two displacement loading protocols: ECCS and AISC
as shown in Figure 12. The protocols consist of applying 30 incremental amplitude displacement cycles in
several steps with a maximum displacement of 2% storey height (60mm) to simulate the experimental test
results. However, the distribution of these cycles is different for each of the two considered loading
protocols. For example, following AISC protocol, the first 6 displacement cycles have an amplitude equal
to yielding displacement of the beam. Then, the displacement amplitudes of each group of 4 identical
cycles is: 2.25δy; 3.5δy; 4.75δy; 6.0δy; 7.25δy; 8.5δy and 1 cycle 10.0δy. Related to the ECCS protocol, the
3
rd
cycle is 1.0δy and it follows in groups of 3 identical cycles incremented with 1.0δy from 2.0δy to 9.0δy,
and the last cycle is 10.0δy.
A comparative response in terms of energy dissipation between experimental (ECCS only) and the
OpenSees braced frame model with dissipative connections, loaded with both displacement protocols is
shown in Figure 13. As illustrated, the total cumulative dissipated energy computed with the OpenSees
9. EM-02-9
model (31 cycles) under both loading protocols equates the energy dissipated during the experimental
test and, in this respect, the OpenSees model of braced frame with single-pin connections is validated.
Figure 12: Loading protocols Figure 13: Cumulative dissipated energy
In addition, the force – displacement hysteresis loops (Figures 14 and 15) shows a maximum
displacement of 60mm and a corresponding force of 800kN. A very good match was obtained between
the experimental results (Plumier et al., 2005) and those simulated in OpenSees (Figure 14). Figure 15
shows the difference in behaviour between both loading protocols. The efficiency in terms of energy
dissipation of ductile braced frames with dissipative connections versus ductile braced frames with shear
connections (CBF) is shown in Figure 16. This result was obtained under a quasi-static analysis when the
ECCS loading protocol was considered. In addition, the fundamental period of the CBF is 0.1s, while the
period of the CBF with dissipative connection is 0.25s. However, further analytical research is required to
emphasize the performance of a CBF with dissipative pin connections.
Figure 14: Force – displacement hysteresis loops: Figure 15: Force – displacement hysteresis loops:
OpenSees model versus experimental (ECCS) OpenSees model (AISC) versus experimental (ECCS)
10. EM-02-10
Figure 16: Comparative response of CBF with and without pin connections: Cumulative energy
5. Conclusions
The braced frame system with dissipative connections is an efficient earthquake resistant structure. Its
efficiency consists of a reduced structural cost and feasibility of pin replacement after seismic events. The
single-pin brace-to-column connections are able to behave in a ductile manner under larger loads and are
capable of protecting braces from buckling. These connections are able to dissipate almost the same
energy when the brace behaves in tension or compression.
The simulated OpenSees model of the braced frame with dissipative single-pin brace-to-column
connections was validated against experimental test results. Further research is required to assess the
seismic performance of this innovative structural system that can be selected for either a new design or
for seismic upgrade.
6. Acknowledgements
This research was supported by the Natural Sciences and Engineering Research Council of Canada. The
authors acknowledge researchers A. Plumier, C. Castiglioni, I. Vayas & L. Calado for providing test data.
7. References
AISC. 2005a. ANSI/AISC 341-05, Seismic Provisions for Structural Steel Buildings. American Institute of
Steel Construction, Chicago, Illinois, USA.
CSA. 2009, Design of Steel Structures, CSA-S16-09, Canadian Standards Association, Toronto, Canada.
Eurocode 8. 2004, Design of structures for Earthquake Resistance, CEN, EU Standartization Committee,
European Convention for Constructional Steelwork (ECCS), 1986. Recommended Testing Procedure for
Assessing Behavior of Struct. Steel Elements under Cyclic Loads, ECCS Publ. no.45, Rotterdam,
Plumier, A., Castiglioni, C., Vayas, I., Calado, L., 2005, Behaviour of seismic resistant braced frames with
innovative dissipative (INERD) connections, EUROSteel Conference, Maastricht 5.2-25 – 5.2-32.
Plumier, A., Doneux, C. 2006, Two Innovations for Earthquake Resistant Design, The INERD Project,
Université de Liège, Liège, Belgium.
Vayas, I., Thanopoulos, P., 2005, Innovative Dissipative (INERD) Pin Connections for Seismic Resistant
Braced Frames, International Journal of Steel Structures, Vol. 5, pp.453–464.