This document discusses raft foundation design concepts for high-rise buildings. A raft foundation is a continuous slab that extends over the entire footprint of a building to transfer its weight uniformly to the soil. It is suitable for buildings with basements. Raft foundations are used when soil bearing capacity is low, loads are high, or differential settlement needs to be minimized. The document describes different types of raft foundations and provides an example design of a slab-beam raft foundation, calculating bending moments, reinforcement requirements, and checking deflection, shear, and cracking.
This document discusses the need for raft foundations. Raft foundations are recommended when:
1) Building loads are heavy or soil capacity is low, so individual footings would cover too much area.
2) Soil contains weak lenses or cavities, making differential settlement hard to predict.
3) Structures are sensitive to differential settlement.
4) Structures like silos naturally suit raft foundations.
5) Floating foundations are needed over very weak soil.
6) Buildings require basements or underground pits.
7) Individual footings would experience large bending stresses.
Raft foundations increase capacity, decrease settlement, and equalize differential settlement compared to individual footings. However,
This resource material is exclusively for the purpose of knowledge dissemination for the use of Civil engineering Fraternity, professionals & students.
This file contains state of art techniques adopted & practiced as per IS456 code provisions for analysis design & detailing of flat slab structural systems.
The presentation aims to provide clear,concise, technical details of flat slabs design.
The presentation deals with structural actions & behavior of flat slabs with visual representations obtained through finite element analysis.
The knowledge gained can be used for designing building structures frequently encountered in construction.
The presentation covers an important feature of slab systems supported on rigid & flexible support & clearly demarcates the minimum beam dimensions required to consider the supports to be either rigid or flexible.
The presentation alsoincludes clear technical drawings to highlight the importance of detailing w.r.t. rebar lay out - positioning & curtailment. Typical section drawing through middle & column strips are also included for visualizing rebar patterns in 3 -d views.
This presentation is an outcome of series of lectures for undergrad & grad students studying in civil engineering.
My next presentation would be on Analysis & design of deep beams.
Kindly mail me ( vvietcivil@gmail.com) your questions & valuable feedback.
Raft foundations are used when buildings have heavy loads, compressible soil, or require minimal differential settlement. A raft foundation is a continuous concrete slab that supports all building columns. It can be designed using either a rigid or flexible approach. The rigid approach assumes the raft bridges soil variations, while the flexible approach models soil-structure interaction. Key considerations for raft design include bearing capacity, settlement, stress distribution, and structural component sizing.
The document describes the design of a stepped footing to support a column with an unfactored load of 800 kN. A square footing with dimensions of 2.1m x 2.1m is designed with two 300mm steps. Reinforcement of #12 bars at 150mm c/c is provided. Checks are performed for bending moment, one-way shear, two-way shear, and development length which all meet code requirements. Therefore, the stepped footing design is adequate to support the given column load.
A reinforced concrete mat foundation is a common type of foundation system used in many buildings. They are a specific type of shallow foundation that uses bearing capacity of the soil at or near the building base to transmit the loads to the soil. Compared to an ordinary slab on grade, a reinforced concrete mat is much thicker and is subjected to more substantial loads from the building.
This document discusses the need for raft foundations. Raft foundations are recommended when:
1) Building loads are heavy or soil capacity is low, so individual footings would cover too much area.
2) Soil contains weak lenses or cavities, making differential settlement hard to predict.
3) Structures are sensitive to differential settlement.
4) Structures like silos naturally suit raft foundations.
5) Floating foundations are needed over very weak soil.
6) Buildings require basements or underground pits.
7) Individual footings would experience large bending stresses.
Raft foundations increase capacity, decrease settlement, and equalize differential settlement compared to individual footings. However,
This resource material is exclusively for the purpose of knowledge dissemination for the use of Civil engineering Fraternity, professionals & students.
This file contains state of art techniques adopted & practiced as per IS456 code provisions for analysis design & detailing of flat slab structural systems.
The presentation aims to provide clear,concise, technical details of flat slabs design.
The presentation deals with structural actions & behavior of flat slabs with visual representations obtained through finite element analysis.
The knowledge gained can be used for designing building structures frequently encountered in construction.
The presentation covers an important feature of slab systems supported on rigid & flexible support & clearly demarcates the minimum beam dimensions required to consider the supports to be either rigid or flexible.
The presentation alsoincludes clear technical drawings to highlight the importance of detailing w.r.t. rebar lay out - positioning & curtailment. Typical section drawing through middle & column strips are also included for visualizing rebar patterns in 3 -d views.
This presentation is an outcome of series of lectures for undergrad & grad students studying in civil engineering.
My next presentation would be on Analysis & design of deep beams.
Kindly mail me ( vvietcivil@gmail.com) your questions & valuable feedback.
Raft foundations are used when buildings have heavy loads, compressible soil, or require minimal differential settlement. A raft foundation is a continuous concrete slab that supports all building columns. It can be designed using either a rigid or flexible approach. The rigid approach assumes the raft bridges soil variations, while the flexible approach models soil-structure interaction. Key considerations for raft design include bearing capacity, settlement, stress distribution, and structural component sizing.
The document describes the design of a stepped footing to support a column with an unfactored load of 800 kN. A square footing with dimensions of 2.1m x 2.1m is designed with two 300mm steps. Reinforcement of #12 bars at 150mm c/c is provided. Checks are performed for bending moment, one-way shear, two-way shear, and development length which all meet code requirements. Therefore, the stepped footing design is adequate to support the given column load.
A reinforced concrete mat foundation is a common type of foundation system used in many buildings. They are a specific type of shallow foundation that uses bearing capacity of the soil at or near the building base to transmit the loads to the soil. Compared to an ordinary slab on grade, a reinforced concrete mat is much thicker and is subjected to more substantial loads from the building.
This document provides an overview of structural steel design and connections. It discusses the benefits of steel structures, common lateral load resisting systems like braced and rigid frames, and types of bracing configurations. It also examines different types of steel frame connections including simple, moment, and eccentric braced connections. Design considerations and capacity equations for moment connections are presented.
This document discusses shear wall analysis and design. It defines shear walls as structural elements used in buildings to resist lateral forces through cantilever action. The document classifies different types of shear walls and discusses their behavior under seismic loading. It outlines the steps for designing shear walls, including reviewing layout, analyzing structural systems, determining design forces, and detailing reinforcement. The document emphasizes the importance of properly locating shear walls in a building to resist seismic loads and minimize torsional effects.
This document outlines the advantages of using post-tensioning in building structures. Post-tensioning allows for longer spans, reduced floor thickness, increased floor area, faster construction speeds, and reduced material usage. It discusses common post-tensioning systems used in building floors and specialized structural elements. Post-tensioning provides more flexible and economical building structures compared to other methods.
The Manual explains the concept of transferring the load from the super structure up to the soil throughout Piles, which has a capacity of (End bearing, and Skin friction). It illustrates the steps needed to produce a full and safe foundation for your Super Structure.
1) Two-way slabs are slabs that require reinforcement in two directions because bending occurs in both the longitudinal and transverse directions when the ratio of longest span to shortest span is less than 2.
2) The document discusses various types of two-way slabs and design methods, focusing on the direct design method (DDM).
3) Using the DDM, the total factored load is first calculated, then the total factored moment is distributed to positive and negative moments. The moments are further distributed to column and middle strips using factors that consider the slab and beam properties.
This document discusses mat and pile foundations. It describes mat foundations as thick reinforced concrete slabs that transmit loads from columns or walls into the soil. Common uses include supporting storage tanks and industrial equipment. It then discusses different types of mat foundations and how load is distributed depending on soil conditions. The document also outlines the typical procedures for constructing a mat foundation, including soil testing, excavation, reinforcement, forming, and curing. Pile foundations are described as using deep foundations when soil bearing capacity is low. Types of piles are classified based on function, material, and installation method. Factors for selecting the appropriate pile type include loads, soil conditions, structure type, and costs.
The document provides details on the design of a reinforced concrete column footing to support a column with a load of 1100kN. It includes calculating the footing size as a 3.5m x 3.5m square to support the load, determining the reinforcement with 12mm diameter bars at 100mm spacing, and checking that the design meets requirements for bending capacity, shear strength, and development length. The step-by-step worked example shows how to analyze and detail the reinforcement of the column footing.
A raft foundation is a large concrete slab that interfaces columns with the base soil. It can support storage tanks, equipment, or tower structures. There are different types including flat plate, plate with thickened columns, and waffle slab. The structural design uses conventional rigid or flexible methods. It involves determining soil pressures, load eccentricities, moment and shear diagrams for strips, punching shear sections, steel reinforcement, and checking stresses. A beam-slab raft foundation design follows the same process as an inverted beam-slab roof.
This document provides an overview of different types of retaining walls, including gravity, cantilever, counterfort, sheet pile, and diaphragm walls. It discusses the key components and design considerations for gravity and cantilever retaining walls. Gravity walls rely on their own weight for stability, while cantilever walls consist of a vertical stem with a heel and toe slab acting as a cantilever beam. The document also covers lateral earth pressures, drainage of retaining walls, uses of sheet pile walls, and construction methods for diaphragm walls.
This document provides guidance on the design of lacing and battens for built-up compression members. It discusses the key design considerations and calculations for both single and double lacing systems, including the angle of inclination, slenderness ratio, effective lacing length, bar width and thickness. Similar guidelines are given for battens, covering spacing, thickness, effective depth, transverse shear and overlap. The document also includes an example problem on designing a slab foundation for a column with given load and material properties.
Connections are critical components that join structural elements to transfer forces safely. Steel connections influence construction costs and failures often originate from connections. Common steel connections include bolted, welded, and riveted joints. Bolted connections can be bearing type or friction grip bolts. Welded joints include fillet and butt welds. Connections must be designed for the expected loads, with shear connections allowing rotation and moment connections resisting it. Proper connection design is important for structural integrity and economy.
This document provides an overview of analysis and design methods for concrete slabs, including:
1. Elastic analysis methods like grillage analysis and finite element analysis can be used to determine moments and shear forces in slabs.
2. Yield line theory is an alternative plastic/ultimate limit state approach for determining the ultimate load capacity of ductile concrete slabs. It involves assuming yield line patterns that divide the slab into rigid regions and equating external and internal work.
3. Examples are provided to illustrate yield line analysis for one-way spanning slabs and rectangular two-way slabs. Conventions, assumptions, and calculation procedures are explained.
This document discusses bearing capacity theory and methods for determining the bearing capacity of soil. It defines key terms like maximum safe bearing capacity, allowable bearing pressure, and net pressure intensity. It describes different types of bearing capacity failure and assumptions in Terzaghi's bearing capacity method. The document also discusses other theories by Meyerhof, Vesic, and Skempton that improved on Terzaghi's method. Finally, it outlines field tests like plate load tests and laboratory tests to directly determine the bearing capacity of soil.
This document provides details on the design of a continuous one-way reinforced concrete slab. It includes minimum thickness requirements, equations for calculating moments and shear, maximum reinforcement ratios, and minimum reinforcement ratios. An example is then provided to demonstrate the design process. The slab is designed to have a thickness of 6 inches with 0.39 in2/ft of tension reinforcement in the negative moment region and 0.33 in2/ft in the positive moment region.
This presentation summarizes the key aspects of one-way slab design. It defines one-way slabs as having an aspect ratio of 2:1 or greater, with bending primarily along the long axis. The presentation discusses the types of one-way slabs including solid, hollow, and ribbed. It also outlines the design considerations for one-way slabs according to the ACI code, including minimum thickness, reinforcement ratios, and bar spacing. An example problem demonstrates how to design a one-way slab for a given set of loading and dimensional conditions.
Behavior of rc structure under earthquake loadingBinay Shrestha
The document discusses reasons why reinforced concrete (RC) structures fail during earthquakes and measures to improve their performance. Key points include:
1) RC buildings often fail due to design deficiencies like ignoring concepts of strong columns-weak beams or having soft stories, or construction defects like weak joints or improper reinforcement detailing.
2) Measures to improve performance include following design concepts of strong columns-weak beams and designing soft story elements to withstand higher forces, as well as improving construction quality of joints and reinforcement details.
3) Other factors that can lead to failure are short column effects, torsional forces from asymmetric shapes, and disturbance of the load path through the structure.
The document discusses reinforced concrete columns, including their functions, failure modes, classifications, and design considerations. Columns primarily resist axial compression but may also experience bending moments. They can fail due to compression, buckling, or a combination. Design depends on whether the column is short or slender, braced or unbraced. Reinforcement is designed based on the column's expected loads and dimensions using methods specified in design codes like BS 8110.
This document is the Indian Standard (Part 1) for earthquake resistant design of structures. It provides general provisions and criteria for assessing earthquake hazards and designing buildings to resist earthquakes. Some key points:
- It defines seismic zones across India based on past earthquake intensities and establishes design response spectra for each zone.
- It provides minimum design forces for normal structures and notes that special structures may require more rigorous site-specific analysis.
- This revision includes changes such as defining design spectra to 6 seconds, specifying the same spectra for all building materials, including temporary structures, and provisions for irregular buildings and masonry infill walls.
- It establishes terminology used in earthquake engineering and references other relevant Indian Standards for
This document provides information on bearing capacity of soil and foundations. It defines key foundation terms like contact pressure, foundation depth, shallow and deep foundations. It describes different types of shallow foundations like spread footing, continuous footing, combined footing, strap footing, and mat or raft footing. Factors for selecting a foundation type and comparing shallow vs deep foundations are also discussed. Design criteria of safety against bearing capacity failure and limiting settlement are covered.
Pile foundations transfer structural loads to deeper, stronger soil strata by bearing loads through end bearing or shaft friction. Piles can be classified as end bearing or friction piles depending on whether they transmit loads primarily through their base or sides. Common pile types include driven piles, which are displaced during installation, and bored piles or replacement piles, which are formed by machine boring. Pile capacity is estimated based on soil properties and load tests may be used to verify estimates.
This document provides an overview of structural steel design and connections. It discusses the benefits of steel structures, common lateral load resisting systems like braced and rigid frames, and types of bracing configurations. It also examines different types of steel frame connections including simple, moment, and eccentric braced connections. Design considerations and capacity equations for moment connections are presented.
This document discusses shear wall analysis and design. It defines shear walls as structural elements used in buildings to resist lateral forces through cantilever action. The document classifies different types of shear walls and discusses their behavior under seismic loading. It outlines the steps for designing shear walls, including reviewing layout, analyzing structural systems, determining design forces, and detailing reinforcement. The document emphasizes the importance of properly locating shear walls in a building to resist seismic loads and minimize torsional effects.
This document outlines the advantages of using post-tensioning in building structures. Post-tensioning allows for longer spans, reduced floor thickness, increased floor area, faster construction speeds, and reduced material usage. It discusses common post-tensioning systems used in building floors and specialized structural elements. Post-tensioning provides more flexible and economical building structures compared to other methods.
The Manual explains the concept of transferring the load from the super structure up to the soil throughout Piles, which has a capacity of (End bearing, and Skin friction). It illustrates the steps needed to produce a full and safe foundation for your Super Structure.
1) Two-way slabs are slabs that require reinforcement in two directions because bending occurs in both the longitudinal and transverse directions when the ratio of longest span to shortest span is less than 2.
2) The document discusses various types of two-way slabs and design methods, focusing on the direct design method (DDM).
3) Using the DDM, the total factored load is first calculated, then the total factored moment is distributed to positive and negative moments. The moments are further distributed to column and middle strips using factors that consider the slab and beam properties.
This document discusses mat and pile foundations. It describes mat foundations as thick reinforced concrete slabs that transmit loads from columns or walls into the soil. Common uses include supporting storage tanks and industrial equipment. It then discusses different types of mat foundations and how load is distributed depending on soil conditions. The document also outlines the typical procedures for constructing a mat foundation, including soil testing, excavation, reinforcement, forming, and curing. Pile foundations are described as using deep foundations when soil bearing capacity is low. Types of piles are classified based on function, material, and installation method. Factors for selecting the appropriate pile type include loads, soil conditions, structure type, and costs.
The document provides details on the design of a reinforced concrete column footing to support a column with a load of 1100kN. It includes calculating the footing size as a 3.5m x 3.5m square to support the load, determining the reinforcement with 12mm diameter bars at 100mm spacing, and checking that the design meets requirements for bending capacity, shear strength, and development length. The step-by-step worked example shows how to analyze and detail the reinforcement of the column footing.
A raft foundation is a large concrete slab that interfaces columns with the base soil. It can support storage tanks, equipment, or tower structures. There are different types including flat plate, plate with thickened columns, and waffle slab. The structural design uses conventional rigid or flexible methods. It involves determining soil pressures, load eccentricities, moment and shear diagrams for strips, punching shear sections, steel reinforcement, and checking stresses. A beam-slab raft foundation design follows the same process as an inverted beam-slab roof.
This document provides an overview of different types of retaining walls, including gravity, cantilever, counterfort, sheet pile, and diaphragm walls. It discusses the key components and design considerations for gravity and cantilever retaining walls. Gravity walls rely on their own weight for stability, while cantilever walls consist of a vertical stem with a heel and toe slab acting as a cantilever beam. The document also covers lateral earth pressures, drainage of retaining walls, uses of sheet pile walls, and construction methods for diaphragm walls.
This document provides guidance on the design of lacing and battens for built-up compression members. It discusses the key design considerations and calculations for both single and double lacing systems, including the angle of inclination, slenderness ratio, effective lacing length, bar width and thickness. Similar guidelines are given for battens, covering spacing, thickness, effective depth, transverse shear and overlap. The document also includes an example problem on designing a slab foundation for a column with given load and material properties.
Connections are critical components that join structural elements to transfer forces safely. Steel connections influence construction costs and failures often originate from connections. Common steel connections include bolted, welded, and riveted joints. Bolted connections can be bearing type or friction grip bolts. Welded joints include fillet and butt welds. Connections must be designed for the expected loads, with shear connections allowing rotation and moment connections resisting it. Proper connection design is important for structural integrity and economy.
This document provides an overview of analysis and design methods for concrete slabs, including:
1. Elastic analysis methods like grillage analysis and finite element analysis can be used to determine moments and shear forces in slabs.
2. Yield line theory is an alternative plastic/ultimate limit state approach for determining the ultimate load capacity of ductile concrete slabs. It involves assuming yield line patterns that divide the slab into rigid regions and equating external and internal work.
3. Examples are provided to illustrate yield line analysis for one-way spanning slabs and rectangular two-way slabs. Conventions, assumptions, and calculation procedures are explained.
This document discusses bearing capacity theory and methods for determining the bearing capacity of soil. It defines key terms like maximum safe bearing capacity, allowable bearing pressure, and net pressure intensity. It describes different types of bearing capacity failure and assumptions in Terzaghi's bearing capacity method. The document also discusses other theories by Meyerhof, Vesic, and Skempton that improved on Terzaghi's method. Finally, it outlines field tests like plate load tests and laboratory tests to directly determine the bearing capacity of soil.
This document provides details on the design of a continuous one-way reinforced concrete slab. It includes minimum thickness requirements, equations for calculating moments and shear, maximum reinforcement ratios, and minimum reinforcement ratios. An example is then provided to demonstrate the design process. The slab is designed to have a thickness of 6 inches with 0.39 in2/ft of tension reinforcement in the negative moment region and 0.33 in2/ft in the positive moment region.
This presentation summarizes the key aspects of one-way slab design. It defines one-way slabs as having an aspect ratio of 2:1 or greater, with bending primarily along the long axis. The presentation discusses the types of one-way slabs including solid, hollow, and ribbed. It also outlines the design considerations for one-way slabs according to the ACI code, including minimum thickness, reinforcement ratios, and bar spacing. An example problem demonstrates how to design a one-way slab for a given set of loading and dimensional conditions.
Behavior of rc structure under earthquake loadingBinay Shrestha
The document discusses reasons why reinforced concrete (RC) structures fail during earthquakes and measures to improve their performance. Key points include:
1) RC buildings often fail due to design deficiencies like ignoring concepts of strong columns-weak beams or having soft stories, or construction defects like weak joints or improper reinforcement detailing.
2) Measures to improve performance include following design concepts of strong columns-weak beams and designing soft story elements to withstand higher forces, as well as improving construction quality of joints and reinforcement details.
3) Other factors that can lead to failure are short column effects, torsional forces from asymmetric shapes, and disturbance of the load path through the structure.
The document discusses reinforced concrete columns, including their functions, failure modes, classifications, and design considerations. Columns primarily resist axial compression but may also experience bending moments. They can fail due to compression, buckling, or a combination. Design depends on whether the column is short or slender, braced or unbraced. Reinforcement is designed based on the column's expected loads and dimensions using methods specified in design codes like BS 8110.
This document is the Indian Standard (Part 1) for earthquake resistant design of structures. It provides general provisions and criteria for assessing earthquake hazards and designing buildings to resist earthquakes. Some key points:
- It defines seismic zones across India based on past earthquake intensities and establishes design response spectra for each zone.
- It provides minimum design forces for normal structures and notes that special structures may require more rigorous site-specific analysis.
- This revision includes changes such as defining design spectra to 6 seconds, specifying the same spectra for all building materials, including temporary structures, and provisions for irregular buildings and masonry infill walls.
- It establishes terminology used in earthquake engineering and references other relevant Indian Standards for
This document provides information on bearing capacity of soil and foundations. It defines key foundation terms like contact pressure, foundation depth, shallow and deep foundations. It describes different types of shallow foundations like spread footing, continuous footing, combined footing, strap footing, and mat or raft footing. Factors for selecting a foundation type and comparing shallow vs deep foundations are also discussed. Design criteria of safety against bearing capacity failure and limiting settlement are covered.
Pile foundations transfer structural loads to deeper, stronger soil strata by bearing loads through end bearing or shaft friction. Piles can be classified as end bearing or friction piles depending on whether they transmit loads primarily through their base or sides. Common pile types include driven piles, which are displaced during installation, and bored piles or replacement piles, which are formed by machine boring. Pile capacity is estimated based on soil properties and load tests may be used to verify estimates.
This document provides information about bearing capacity of soil and different types of foundations. It discusses key topics like:
- Types of foundations including shallow foundations like spread footings, continuous footings, combined footings, strap footings, and mat/raft foundations. It also discusses deep foundations.
- Factors that determine the selection of a foundation type including the structure's function/loads, sub-surface soil conditions, and cost.
- Comparison of shallow and deep foundations in terms of depth, load distribution, construction, cost, structural design considerations, and settlement.
- Criteria for foundation design including safety against bearing capacity failure and limiting settlement, especially differential settlement.
This document provides an overview of pile foundations and their design. It discusses different types of piles including end bearing piles, friction piles, displacement piles, and replacement piles. Modes of pile failure and factors in total and effective stress analysis are examined. Advantages and disadvantages of displacement and replacement piles are compared. Methods for predicting the ultimate capacity of axially loaded single piles in soil are outlined, including considerations for driven piles in clays and bored piles in both granular and clay soils. Load-settlement behavior of friction and end bearing piles is also addressed.
This document discusses pile foundations and methods for analyzing pile capacity. It begins with an introduction to pile foundations, including how they transfer structural loads through unstable upper soils. It then discusses different pile types classified by installation method, including large displacement, small displacement, and replacement piles. The document outlines factors that influence pile capacity, such as soil properties and loading conditions. It provides advantages and disadvantages of driven and replacement piles. Finally, it discusses methods for predicting ultimate pile capacity, including total and effective stress analysis, skin friction and end bearing resistance calculations, and pile load testing.
This document discusses pile foundations and provides details on:
- Types of pile foundations including driven piles, bored piles, and under-reamed piles
- Analyzing pile capacity using driving formulae, soil mechanics expressions considering shaft resistance, base resistance, and factors like soil type, pile dimensions, and installation method
- Calculating pile capacity in cohesive soils like clay and non-cohesive soils like sand, accounting for soil strength properties and effective stresses
- Considerations for negative skin friction from consolidating or compacting soil layers
All mat-raft-piles-mat-foundation- اللبشة – الحصيرة العامة -لبشة الخوازيق ( ا...Dr.Youssef Hammida
This document provides guidance on the steps required for designing mat foundations with piles. The key steps include:
1) Determining total vertical loads and adding 1% for eccentricity.
2) Dividing the total load by the allowable soil bearing capacity to determine the number of piles.
3) Checking stresses on the mat and piles, including uplift, shear, and moment forces as required.
4) Calculating free pile length and location of fixity based on soil properties.
5) Designing the mat and piles considering both vertical and horizontal/seismic loads.
design of piled raft foundations. مشاركة لبشة الأوتاد الخوازيق و التربة في ...Dr.youssef hamida
Of the most important paragraphs of design should study the effect of the Joint Working Group of the falling pile and fall of the soil and find a formula and factor common reaction one between sub grade reaction smart spring worker and worker response pile reaction called spring factor smart In the case of soil subsidence greater than the drop pile will move full load
piles and breaks down to piles or mat and vice versa
In the event of high rises and soil carried acceptable but not enough for the transplant can mat- piles
Regular spacing and share the soil with piles represent the programs work as usual spring network
And the introduction of sub grade reaction as factor in mat alone as well as the added factor reaction pile at each pile
But the application of this method takes the soil report by the impact of joint work between the soil decline and fall of the stake and the coefficient of reaction and give him carrying a load of soil and allowed the pile needs
Also must make sure that the applicable tag allows participation in this way the soil and pile in the joint
Assume springs for soil and piles
getting modulus of sub grad
This document defines foundations and foundation engineering. It discusses shallow and deep foundations. Shallow foundations include spread, combined, wall/strip, and mat foundations. Deep foundations include piles and piers. It describes factors in foundation design such as ultimate bearing capacity, settlement, and differential settlement. Footing failures by shear, tension, or bearing capacity are addressed. Examples of isolated, combined, and wall footings are provided along with factors in selecting the appropriate foundation type.
This document defines foundations and foundation engineering. It discusses:
1. Foundations transmit structural loads to the soil and come in two types - shallow and deep. Shallow foundations are placed at a shallow depth, typically less than 6m, and include spread footings and strip footings. Deep foundations like piles are embedded much deeper.
2. Foundation engineering involves evaluating soil load capacity and designing foundations to safely transmit loads to the soil while considering economics. It must prevent shear failure, settlement, overturning and sliding.
3. Foundations can fail due to shear, tension or excessive settlement, which depends on factors like soil type and load. Design considers ultimate and allowable bearing capacity as well as allowable settlement.
This document discusses the design of reinforced concrete slabs. It begins by introducing different types of slabs used in construction like solid slabs, flat slabs, ribbed slabs, and waffle slabs. It then covers simplified analysis methods for slabs spanning in one or two directions using load and moment coefficients. The document also addresses shear design in slabs, discussing shear stresses and the need for shear reinforcement. It concludes by discussing punching shear analysis around concentrated loads and the importance of limiting span-depth ratios to control deflections in slabs.
This document discusses the types and components of concrete pavements. It describes concrete pavements as rigid slabs made of Portland cement that have very small deflections compared to flexible pavements. The main components are the concrete slab, granular or stabilized base and subbase, and subgrade. Joints like contraction joints, construction joints, and expansion joints are also important features. The document also examines stresses in concrete from loads, temperature changes, and other factors using theories like modulus of subgrade reaction. It provides equations to calculate stresses at critical interior, edge, and corner locations of slabs.
This document discusses the design of two-way floor slabs and footings. It covers the direct design method for two-way slabs without beams, examples of slab design, shear failure mechanisms, design for two-way shear, and shear reinforcement options. For footings, it defines footing types, soil pressure distribution, design considerations including bearing capacity and reinforcement, sizing footings based on soil pressure, and design for one-way and two-way shear as well as flexural strength. It also addresses bearing capacity at the column base and dowel requirements.
This document discusses mat foundations. It begins by introducing mat foundations as a type of combined footing that can support an entire structure. It describes common types of mat foundations including flat plates, plates thickened under columns, beams and slabs, and slabs with basement walls. It then covers calculating the bearing capacity of mat foundations, considering factors for shape, depth, and soil properties. Graphs are provided showing variations in allowable bearing capacity. Methods are presented for determining bearing capacity in clays and sands based on soil strength properties and settlement.
This document discusses the bearing capacity of bedrock and soil deposits on slopes. It provides definitions of key terms like ultimate and allowable bearing capacity. It describes various methods for calculating bearing capacity, including equations that account for factors like rock mass quality, joint spacing, slope angle, and soil type. Failure modes like general shear, local shear, and punching shear are also outlined. The document notes how soil deposits form on slopes and factors affecting the stability of soils on steep slopes, both natural and human-related.
lecturenote_1463116827CHAPTER-II-BEARING CAPACITY OF FOUNDATION SOIL.pdf2cd
The document discusses bearing capacity of soils and methods to calculate the ultimate and safe bearing capacities of different types of foundations. It defines key terms like ultimate, gross, net and safe bearing capacities. It describes Terzaghi's, Meyerhof's and Skempton's methods to calculate the bearing capacity based on the soil properties and foundation geometry. It provides examples to calculate the ultimate and safe bearing capacities of strip, square, circular and rectangular foundations in cohesive and cohesionless soils using these methods.
This document discusses the bearing capacity of soils and foundations. It defines bearing capacity as the load per unit area that can be supported by a foundation without failing. Several methods for calculating ultimate bearing capacity are presented, including Terzaghi's method, which uses bearing capacity factors that depend on soil properties. The document also discusses factors that affect bearing capacity like the water table, foundation shape and depth, layered soils, sloped ground, and estimates from standard penetration or cone penetration tests. Failure modes like general, local, and punching shear are described along with calculations for eccentric and two-way loading.
This document discusses different types of foundations for structures. It describes shallow foundations like spread footings, combined footings, cantilever footings, continuous footings, and raft foundations. It also describes deep foundations like piles, piers, and caissons. The key factors in selecting a foundation type are the structure's loads, subsurface soil conditions, and cost. Foundation design considers load distribution, settlement, and preventing differential movement.
The document discusses pile foundations and their design. It describes different types of piles including end bearing piles, friction piles, displacement piles, and replacement piles. It covers topics such as pile capacity calculation considering end bearing and skin friction, methods of installation, failure modes, total and effective stress analysis, and prediction of pile capacity through pile driving formulas and load testing.
Online train ticket booking system project.pdfKamal Acharya
Rail transport is one of the important modes of transport in India. Now a days we
see that there are railways that are present for the long as well as short distance
travelling which makes the life of the people easier. When compared to other
means of transport, a railway is the cheapest means of transport. The maintenance
of the railway database also plays a major role in the smooth running of this
system. The Online Train Ticket Management System will help in reserving the
tickets of the railways to travel from a particular source to the destination.
An In-Depth Exploration of Natural Language Processing: Evolution, Applicatio...DharmaBanothu
Natural language processing (NLP) has
recently garnered significant interest for the
computational representation and analysis of human
language. Its applications span multiple domains such
as machine translation, email spam detection,
information extraction, summarization, healthcare,
and question answering. This paper first delineates
four phases by examining various levels of NLP and
components of Natural Language Generation,
followed by a review of the history and progression of
NLP. Subsequently, we delve into the current state of
the art by presenting diverse NLP applications,
contemporary trends, and challenges. Finally, we
discuss some available datasets, models, and
evaluation metrics in NLP.
We have designed & manufacture the Lubi Valves LBF series type of Butterfly Valves for General Utility Water applications as well as for HVAC applications.
Sachpazis_Consolidation Settlement Calculation Program-The Python Code and th...Dr.Costas Sachpazis
Consolidation Settlement Calculation Program-The Python Code
By Professor Dr. Costas Sachpazis, Civil Engineer & Geologist
This program calculates the consolidation settlement for a foundation based on soil layer properties and foundation data. It allows users to input multiple soil layers and foundation characteristics to determine the total settlement.
This is an overview of my current metallic design and engineering knowledge base built up over my professional career and two MSc degrees : - MSc in Advanced Manufacturing Technology University of Portsmouth graduated 1st May 1998, and MSc in Aircraft Engineering Cranfield University graduated 8th June 2007.
1. DESIGN CONCEPTS IN RAFT FOUNDATION FOR HIGH RISE
BUILDINGS
DEPARTMENT OF CIVIL ENGINEERING
V.S SATHEESH
ASSOCIATE PROFESSOR
KUPPAM ENGINEERINGCOLLEGE
2. RAFT FOUNDATIONS
Also known as Mat foundations
It is a continuous slab resting on the soil
Extends over the entire footprint of the building thereby supporting the building
and transferring its weight to the ground.
Best suitable when have a basement floor (High rise structures)
3. RAFT FOUNDATIONS
When do we need a raft foundation?
Bearing capacity of the soil is low
Load to be transferred to the ground is high
Deep foundation becomes uneconomical
More number of columns
The total footing area is greater than 50% of the building area
4. RAFT FOUNDATION
Advantages
Supports large number of columns
Helps overcome differential settlement
Distributes the loads on a wider area thereby not exceeding allowable
bearing capacity
The only shallow foundation to carry heavy loads
Can carry lateral loads too
Resists uplift pressure
5. RAFT FOUNDATIONSTYPES
Flat SlabType Raft Foundation
Used when the columns are equally
spaced
Meaning uniform pressure throughout
the slab.
Slab has uniform thickness
6. RAFT FOUNDATIONSTYPES
Slab-BeamType Raft Foundation:
Used when column loads are unequally
distributed .
To avoid excessive distortion of the structure
as a result of variation in the load distribution
on the raft. In this type of raft foundation
beams are provided with the flat slabs.
7. RAFT FOUNDATIONSTYPES
Slab-BeamType Raft Foundation:
The beams add stiffness to the raft foundation.
The foundation slabs are reinforced with two
more steel meshes. One placed on the lower face
and another at the upper faces of the raft
foundation.
The raft beams are reinforced with strong stirrups
and bars placed at the upper and lower faces.
8. RAFT FOUNDATIONSTYPES
CellularType Raft Foundation:
In case of heavy structures on loose
soil or when soil tends for uneven
settlement, the thickness required
will be more than 1m.
In such case, cellular raft foundation
is more preferable than ordinary raft
foundation.
9. RAFT FOUNDATIONSTYPES
CellularType Raft Foundation:
Consists two slabs where a beam is
constructed of two slabs in both
directions forming hollow cellular raft
foundation.
These foundations are highly rigid and
more economical than other
foundations in such type of poor soil
10. RAFT FOUNDATIONSTYPES
Piled Raft foundation
When the soil so weak that there is an
excessive settlement of the raft slab then Raft
slab is laid on the piles.
Load is carried by the raft slab and settlement
is resisted by piles
11. DESIGN OF RAFT SLAB
Two approaches
Rigid foundation approach
Flexible foundation approach
Rigid Approach - In rigid foundation approach, it is presumed that raft is rigid enough to
bridge over non-uniformities of soil structure. Pressure distribution is considered to be
either uniform or varying linearly.
(a) Inverted floor system (b) Combined footing approach
In rigid rafts, differential settlements are comparatively low but bending moment and
shear forces to which raft is subjected are considerably high
12. DESIGN OF RAFT SLAB
Flexible Approach
In this approach, raft distributes the load in the area immediately surrounding the
column depending upon the soil characteristics.
Differential settlements are comparatively larger but bending moments and shear
forces are comparatively low.Two approaches
(a) Flexible plate supported on elastic foundation, i.e., Hetenyi'sTheory
(b) Foundation supported on bed of uniformly distributed elastic springs with a spring
constant determined using coefficient of sub-grade reaction. Each spring is presumed
to behave independently, i.e., Winklers's foundation
13. DESIGN OF RAFT SLAB
Pressure distributed under the raft
(1) The nature of the soil below the raft
(2) The nature of the foundation, i.e., whether rigid, flexible or soft
(3) Rigidity of the super-structure
(4) The quantum of loads and their relative magnitude
(5) Presence of adjoining foundation
(6) Size of raft
(7) Time at which pressure measurements are taken
15. DESIGN OF RAFT SLAB
Settlement of Raft Slab
The total settlement under the raft foundation can be considered to be made up
of three components, i.e.,
S = Sd+Sc+Ss
Where,
Sd is the immediate or distortion settlement
Sc the consolidation settlement and
Ss is the secondarycompression settlement
16. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Design of Slab-beam type raft slab (Inverted slab)
The most common approach in Medium rise residential/commercial buildings
The raft slab is designed as an inverted slab
The uplift pressure is the loading on the slab, for which BM and SFs are
calculated
The raft beams stiffen the raft slab
Raft beams are designed as inverted floor beams subjected to uplift pressure
17. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Area of the slab will be equal
to footprint of the building.
Cantilever portions are not
always necessary, depends on
the area required
18. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Example for discussion
Design a raft footing for the
foundation plan shown. Assume SBC
150kN/m2
C1 – 300x300 – 800 kN
C2 – 300x300 – 600 kN
19. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Solution : -
Calculation of column loads
Load from column C1 = 3 x 800 = 2400 kN
Load from column C2 = 6 x 600 = 3600 kN
Total load on Foundation = 6000 kN
Self weight of Foundation, 10% = 600 kN
Total load, w = 6600 kN
Area of footing required, A = 6600/150 = 44 m2 - SBC = 150kN/ m2
Footprint area of the grid = 6.3x6.3 = 39.69 m2 < Area required.
20. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Adopt a size of 7mx7m = 49m2
Since, the grid cannot be changed, Extend
the raft on the edges on all four sides as
shown in the figure.
Now this area would be sufficient.
Sadat Ali Khan, The Maldives National University
21. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Net upward pressure,
p = Load of columns/Area provided
p = 6000/49 = 122.45 kN/m2 < SBC
Slab-beam type Raft slab is designed as inverted slab subjected to the Upward pressure 122.45
kN/m2
The raft slab has interior panels as well as a cantilever portion as shown above.
Hence we have to design both Interior panel and the cantilever portion.
22. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
A) Cantilever Slab
Bending Moment, M = 1.5 x wl2 / 2 = 1.5 x 122.45 x 0.352 / 2
M = 11.25 kN-m
B) Interior Panel
Ly = 3m, Lx = 3m
Ly/Lx = 1
Referring Table 26, page 91, IS-456,
23. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
For Interior panels,
Negative moment coefficients at continuous
edge along short span αx = -0.032, along longer
span αy = - 0.032
Positive moment coefficients at midspan along
short span αx = -0.032, along longer span αy =
- 0.032
24. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Bending Moments are calculated using the following formulae,
Negative bending moment, Mx = My = 0.032 x1.5x 122.45 x 32 = 52.89 kN-m (at
supports)
Positive bending moment, Mx = My = 0.024x1.5x122.45x 32 = 39.67 kN-m (at
Midspan)
25. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Depth required, Mu = 0.138fck bd2
52.89x106 = 0.138x20x1000d2
d = 138.43 mm
Adopt d = 150mm and a cover of 50mm, D = 200mm
Area of steel required,
For negative moment, Mu = 0.87 *fy *Ast (d-0.42Xu,max)
52.89 x 106= 0.87 x 415 x Ast (150 – 0.42(0.48x150))
Ast = 1223.19 mm2
Using 16 dia bars, spacing required = 201x1000/1223.19 = 164.4mm
PlaceT16 @ 150mm c/c
Area of steel provided, Ast = 1340 mm2
26. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Similarly for positive moment,
Ast = 917.45 mm2
Using 16 dia bars, spacing required = 201x1000/917.45 = 219.08mm
PlaceT16 @ 150mm c/c
Area of steel provided, Ast = 1340 mm2
27. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Check for deflection
Steel stress of service, fs = 0.58 * fy * 1223.19/1340 = 219.72 N/mm2
Percentage steel provided is 0.67
Referring fig.4, IS456, Modification factor is 1.4
Minimum depth, d min = 3000/26/1.4 = 82 mm
Allowable s/d ratio = 1.4x26 = 36.4
Provided s/d ratio = 3000/200 = 15
Hence the section safe in deflection
28. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Check for Shear
Shear force,Vu = 122.45 x 3/2 = 183kN
Shear stress,Tv =Vu/bd = 1.22N/mm2
Now, 100Ast/bd = 0.8933, Referring to table 19,
Design shear strength, k*Tc = 1.2 x 0.6 = 0.72 N/mm2
Shear reinforcement is required
Let’s provide bent-up bars,
Area of shear reinforcement, forVus = 1.22 – 0.72 = 0.5 N/mm2
Asv =Vus/(σsv*Sinα) = 0.5x1000x150/(230*sin45) = 461.15 mm2
ProvideT12 @ 200mm c/c
29. Check for cracking
The steel provided is more than 0.12% of gross area
Spacing is less than 3d
Hence the section is safe
DESIGN OF SLAB-BEAMTYPE RAFT SLAB
30. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Design of Raft Beams
Uplift pressure 122.45 kN/m2
Load carried by foundation/raft beams is
shown in the figure beside.
FB1 carries the load distributed on two
triangles,
FB2 carries the load distributed on one
triangle and a portion of cantilever
Sadat Ali Khan, The Maldives National University
31. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Design of FB1
Area of loading = (0.5x3x3)x2 = 9 m2
Loading on the beam, w = 122.45x9/3 = 367.35kN/m
Moment at supports, Mu = 1.5xwl2 / 10 = 1.5 x 367.35 x 32 /10 = 495.92 kN-m (Table-12)
Moment at mid span, Mu = 1.5xwl2 / 12 = 1.5 x 367.35 x 32 /12 = 413.27 kN-m
Depth of the beam, d min, Mu = 0.138fckbd2 , assuming b = 400mm
d min = 670.22 mm,
Adopt d = 720 mm, cover = 30mm
Over all depth D = 750mm
32. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Design of FB1
Mu lim will be greater than Mu
Beam can be designed as singly reinforced
Ast reqd = 2322.17 mm2
Provide 8-T20
Ast Provided = 2512mm2
33. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Design of FB1
Check for shear
Shear Force,Vu = 1.5x367. 35x3x0.6 =991.84kN (Table 13, SF Co-efficient)
τv = 661.23x1000/(300x800) = 4.132 N/mm2
100Ast/bd = 0.872
τc = 0.59 N/mm2,τc max = 2.8 N/mm2
34. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Design of FB1
Section requires shear reinforcement
Vc = 0.59x400x720 = 169.92kN
Shear to be resisted,Vus =Vu –Vc = 821.9kN
S = 0.87*fy*As*d/Vus = 0.87x415x4x78.55x800 / 821920 = 110.42mm c/c
Provide 4-legged stirrups at 100 mm c/c
35. DESIGN OF SLAB-BEAMTYPE RAFT SLAB
Structural details of FB1
Sadat Ali Khan, The Maldives National University
36. CASE STUDIES
Project -1
Design of Raft
foundation for a
6 floor building
Sadat Ali Khan, The Maldives National University
37. CASE STUDIES
Project -1
Design of Raft foundation for a 6 floor building.
Sadat Ali Khan, The Maldives National University
38. CASE STUDIES
Project -1
Details of Raft foundation
Sadat Ali Khan, The Maldives National University
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