IRJET- Dynamic Analysis of Tall Tubular Steel Structures of Hexagon Configuration by Incorporating Additional Structural System

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 07 | July 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1283
DYNAMIC ANALYSIS OF TALL TUBULAR STEEL STRUCTURES OF
HEXAGON CONFIGURATION BY INCORPORATING ADDITIONAL
STRUCTURAL SYSTEM
Manoj Kumar S R1, Ramya B V2, Sowmya R H3
1Post Graduate in Structural Engineering, BIET College, Davanagere-577004, India
2Asst, Professor, M. Tech Structural Engineering, BIET College, Davanagere, India
3Asst, Professor, M.Tech Structural Engineering, BIET College, Davanagere, India
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Abstract - In structural engineering, The structural frames
are the load resisting systems. The analysis and design of
structures particularly tall structures needs appropriate
analysis methods, precise design concepts along with
preliminary designs aided with optimisation, in order to
resist the gravity as well as lateral load, so that structure
remains safe thought its life span. In extremely tall buildings
stiffness plays a very important role in controlling the global
displacements. Hence new structural systems are developed
by combining the previous structural systems in order to
resist effectively the lateral loads due to earthquake and
wind and to limit global displacements, drifts and
accelerations under control. The tube structural concept
had become more popular structural systems particularly
for high rise steel structures. The basic structural form
consist of vertical columns positioned about 1 to 2 m centre
to centre, which are connected by deep spandrels, To
understand the behaviour of the tall tubular steel structures
for geometric configurations like hexagonal shapes in plan,
in comparison with the steel beam column rigid frame
system, were analysed using ETABS 2016. The effect of
geometric configurations on behaviour of tall tubular steel
structures are summarised using the obtained results, by
concluding the optimum geometric configuration for tall
tubular steel structures.
Key Words: Tube structure, Diagonal bracings,
Earthquake zones, wind load, Base shear, Story drift,
Story displacement and ETABS.
1. INTRODUCTION
The load resisting sub-system of structure is
considered as structural systems or frame in structural
engineering. Appropriate 0analysis methods are used for
the analysis and design of structures especially for high
rise structures, vertical load like gravity load seismic load
wind load are acting on tall structures, structure should be
able to withstand all these vertical and horizontal load
throughout its life span. The most important factor in
structural engineering is strength serviceability and
stability of the structures, stability is explained by factor of
safety against P-delta effect and buckling, strength is
explained by limit stress and serviceability by lateral drift
Most necessarily the human comforts are influenced by
accelerations of the structures due to dynamic loads. The
main objective of a structural engineer is to fulfil all these
circumstances and lastly to develop a proper structural
schemes, geometric configurations to understand the
behaviour of structural systems before implementation in
real time scenarios.
1.1. Function and importance of structural systems
Now a days tall structures in the city is more
common and due to migration of people in urban areas
which in turns getting higher requirement of tall structure
not only tall structures safety of the structure plays major
role. Because of deficiency of land in extremely urbanized
areas it requires a new innovation in structures to words
to build high rise or skyline structures to fulfil all the
requirements.
Tall structures are cantilevered perpendicular to
the ground. Nowadays, the advancements in structural
systems, increase in building height and slenderness, use
of high strength materials, reduction of building weight
etc., has necessitated the consideration of lateral loads
such as wind and earthquake in the design process. Lateral
forces resulting from wind and seismic activities are now
dominant in design considerations. Lateral displacement of
such buildings must be strictly controlled, not only for
occupants comfort and safety, but also to control
secondary structural effects. In this wild growing
generation there is a need for tall, particularly super tall
structures, where its height may be in range of 300m to
500m. In order to reach structural reliability as whole and
structural soundness between the components of the
super high rise structure, different structural systems are
established.
1.2 Categorization of structural systems
Mainly the Structural Systems are categorised into 4
types.
 Type 1 – Shear Frames
 Type 2 – Interacting frames
 Type 3 – Partial Tubular frames
 Type 4 – Tubular Systems

1.3 Classification of Tube structures
Basic forms of tubular systems are
 Framed tube
 Braced tube
 Bundled tube
 Tube-in-tube
 Tubed mega frame
1.4 Objectives studies
1. To know the performance of the tall tubular steel
structures for hexagon geometric configuration in
plan, in comparison with the reference model of
steel beam column rigid frame system.
2. Earth quake0Analysis is carried out in ETABS 2016
using response spectrum analysis for different
seismic zones using IS 1893-2002. Also
wind0analysis is carried out to recognise the
performance under the wind loads.
3. Efficiency of tall tubular steel structures with respect
the base shear, story and peak displacement, drift
and time period are recorded.
4. To reducing the displacements and story drifts,
bracings can be incorporated to hexagonal tubular
structure as an additional structural systems and
analysis is carried out by response spectrum
method.
5. From the analysis the results obtained for moment
resisting frame, hexagonal tube structure and
hexagonal tube with bracings structure are
comparing.
6. Using the obtained results the outcome of hexagon
geometric configuration on performance of tall
tubular steel structures are summarised.
2. DATA FOR DEVELOPING THE MODEL
Using ETAB 2016 Structural modelling of steel
framed tall tubular structure is made for hexagon shape
geometric configuration, with a regular steel moment
resisting frame section. All the models having equal
number of stories which is 88 numbers and constant floor
area constant diaphragm to take lateral loads and
transmits to beams are provided for all the models to
obtain the consistent results for lighting, ventilation and
service criteria a central core is permitted.
2.1 Building Data
Type of Structure- Steel Moment Resisting Framed tube
square in plan
Plan Configurations - Hexagon and Hexagon with diagonal
bracings
Story details - G+87 (88 Storied)
Height between the floors- 3.6 m
Total building height - 316.8 m
Floor Area - 3550 m2
Building type - Office Building
2.2 Material Properties
Structural Steel Grade - 345 Grade
Concrete Grade - M30 (Deck Slab)
2.3 Section Properties
Column Sections - Built up (ISWB 600)
Beam Sections - ISMB 600
Deck Section - 200mm thick
Bracings Section - ISHB 150
2.4 Loads consideration
a) Gravity load:
Live load - 4.00kN/m2
Floors finish - 1.50kN/m2
Exterior Glazing - 2.00kN/m
b) Earth quake data based on IS1893 (Part0I):2002
Location of Building - All intensity zones
Soil type - Type II (Medium)
Importance factor - 1.0
Response reduction factor - 5.0
Fundamental Natural Period - 6.382 seconds
c) Wind load pattern – Indian IS875:1987
Exposure and pressure coefficients: Exposure from
Extents of Diaphragms is considered and following in puts
are given.
Wind Speed Vb - 33 m/s
Terrain Category - 4
Structure Class - C
Risk Co-efficient - 1
Topography Factor - 1
2.5 Geometric Configurations of Framed Tube
Structures
The following modelling can be done for present study
using ETABS 2016 software that are steel moment
resisting frame and hexagonal geometric configurations
and hexagonal with bracings.

a) Model 1 : Steel Moment Resisting frame : Square in
Plan
Fig – 1: Steel Moment Resisting Frame: Square in Plan
b) Model 2 : Framed tube structure : Hexagonal in
Plan
Fig – 2: Framed Tube Structure: Hexagonal in Plan
c) Model 3: Framed Tube Structure with bracings:
Hexagonal in Plan
Fig – 3: Framed Tube Structure with bracings: Hexagonal
in Plan
3. RESULTS AND DISCUSSIONS
3.1 Modal Analysis
Hexagonal tube structure having maximum time
period which is 25.408 seconds and which is 34% more
than that of steel reference structure. Time period for
hexagonal bracing tube structure is 9.31% lesser than
that of steel moment resisting frame. From the frequency
values highest value is for model 3 i.e., for hexagonal tube
with bracing structure which is 0.058 cycles/sec
a) Mode vs. Time Period
Chart -1: Mode V/s Mode (time) period for different
models
b) Mode vs. Frequency
Chart -2: Mode V/s frequency period for different models

3.2 Earth Quake Analysis results: Response Spectrum
Method
a) Low Seismic Intensity: Zone II
Chart – 3: Maximum ase shear for Zone II
Chart -4: Story Displacements for Zone II
Chart -5: Story Drifts for Zone II
b)Moderate Seismic Intensity: Zone III
Chart – 6: Maximum base shear for Zone III
Chart -7: Story Displacements for Zone II
Chart -8: Story Drifts for Zone III
c) Severe Seismic Intensity: Zone IV
Chart – 9: Maximum base shear for Zone IV

Chart -10: Story Displacements for Zone IV
Chart -11: Story Drifts for Zone IV
d) Very severe Seismic Intensity: Zone V
Chart – 12: Maximum base shear for Zone V
Chart -13: Story Displacements for Zone V
Chart -14: Story Drifts for Zone V
3.3 Results of Wind Analysis
Chart -15: Story Displacements for Wind Analysis
Chart – 16: Story Drifts – Wind Analysis
4. Conclusions
i. Form the modal analysis results, it can be concluded
that more time period value i.e., 25.410seconds is
obtained in the first mode of vibration for hexagonal
tube structure which is 34% more than the reference
structure and also this hexagonal tube structure having
low frequency 0.0390cycles per second. Hence from
the point of assessment of frequency and time period
this structure can be considered as stable.
ii. From the response spectrum analysis results for all
intensity zones, it can be seen that base shear increases
in the model with higher seismic intensity, i.e., seismic
intensity is proportional to the seismicity of building.

iii. From the earthquake analysis, it can be established
that in all seismic zones the hexagonal tall tubular steel
structure having a displacement of 1.86 times and
story drift 2 times higher than the steel moment
resisting structure.
iv. From the wind analysis results, comparing to steel
moment resisting frame the hexagonal tube structure
having a story displacement of 2.66 times and story
drift of 3.05times higher.
v. Therefore in order to reduce displacement and story
drift of hexagonal tube structure and also for
increasing the strength of structure by incorporating
additional structural system like bracings, Provision of
bracings was found0to be effective in increasing the
overall seismic response and characteristics of the
structure,
vi. Comparing to hexagonal structure the hexagonal tube
with bracing structure shows lesser displacement and
story drift and which is almost equal to the reference
structure in all the intensity zones of earthquake
analysis and also for wind analysis.
vii. From the analysis results and consideration it can be
decided that dynamic analysis is more desirable to
identify the accurate response of the tall structural
system.
viii. Form the complete results and examination it can be
concluded that hexagonal plan tubular structure is
more suitable for tall structures than the proper beam
column moment resisting steel frame system.
REFERENCS
[1] Arvind, J.S. and Helen Santhi, M. (2015) “Effect of
Column Shortening on the Behaviour of Tubular
Structures.” Indian Journal of Science and Technology,
Vol 8(36).
[2] Dileep, N., and Renjith, R. (2015) “Analytical
investigation on the performance of tube-in-tube
structures subjected to lateral loads.” International
Journal of Technical Research and Applications. Vol. 3,
(4), 284-288.
[3] Han, R.P.S.(1989) “Analysis of framed tube
structures of arbitrary sections”. Applied
Mathematical Modelling, Vol. 13.
[4] Hong, F., Li, Q.S., Tuan, A.Y. and Xu, L. (2009)
“Seismic analysis of the world’s tallest building.”
Journal of Constructional Steel Research, 65 1206–
1215.
[5] Li, Q.S., Zhang, Y.H., Wu, J.R. and Lin, J.H. (2004)
“Seismic random vibration analysis of tall buildings.”
Engineering Structure, 26, 1767–1778.
[6] Lu, X.L. and Jiang, H.J. (2011) “Research and Practice
of Response Control for Tall Buildings in Mainland
China.” Procedia Engineering, 14, 73–83.
[7] Nishant, R., and Siddhant, R. (2014) “Structural
Forms Systems for Tall Building Structures.”SSRG
International Journal of Civil Engineering, (SSRG-
IJCE). Vol. 1, (4).
[8] Patil, S. and Kalwane U. (2015) “Shear lag in tube
structures.” International Journal of Innovative
Science, Engineering & Technology. Vol. 2 (3).
[9] Pekau, Lin, L. and Zielinski, Z.A. (1996) “Static and
dynamic analysis of tall tube-in-tube structures by
finite story method.” Engineering Structures, Vol. 18,
(7), 515-527.
[10] Richard, A. Ellis and David P. Billington (2003)
“Construction history of the composite framed tube
BIOGRAPHIES
MANOJ KUMAR S R Post
Graduate Student Dept. of
Civil Engineering BIET
College, Davanagere.
RAMYA B V
Asst. Professor Dept. of Civil
Engineering BIET College,
Davanagere.
SOWMYA R H
Asst. Professor Dept. of Civil
Engineering BIET College,
Davanagere.

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