Seismic Performance Analysis: Circular and Rectangular Building Models

This report presents a comparative study of the seismic performance of circular and rectangular building plans constructed on soft rocky soil in seismic zone V of India, as per IS: 1893-2016. The study utilizes STAAD PRO software for linear static analysis of four different building models, considering both strong column-weak beam and strong beam-weak column scenarios. The objective is to evaluate the behavior and performance of these building frames under seismic loads. The results indicate that the circular symmetric building plan with strong columns and weak beams performs better compared to other configurations. The report emphasizes the importance of avoiding the construction of rectangular symmetric buildings with strong beams and weak columns in earthquake-prone regions. The analysis covers various aspects including the effects of different column and beam dimensions, the impact of loading, and the application of relevant Indian standards. The findings provide valuable insights for structural engineers and architects involved in designing earthquake-resistant buildings, highlighting the significance of plan symmetry and the selection of appropriate structural elements to mitigate seismic damage. The report includes detailed tables, figures, and a comprehensive methodology section, along with discussions on the scope for future studies and concluding recommendations.

ABSTRACT
In India, multi-stored buildings are usually constructed due to high cost and scarcity
of land. In order to utilize maximum land area, building and architects generally
propose asymmetrically plan configurations. These unsymmetrical plan buildings,
which are constructed in seismic prone areas, are likely to experience more damage
during earthquake. Earthquake is a natural phenomenon which can generate the most
destructive forces on structures. In the present study, four different models with
symmetric circular and rectangular plan constructed on soft rocky soil in seismic
zone V of India (as per IS: 1893-2016) are considered. Linear and static analysis
using the software in STAAD PRO is carried out for all the plan. The objective of the
present study is to study the behavior and comparison of building frames under strong
column and weak beam & strong beam and weak column. It is observed that the
building with circular symmetric plan with strong column and weak beam performs
well compared to the other building plan. It is recommended that construction of
rectangular symmetric building with strong beam and weak column should be avoided
in earthquake prone regions.
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LIST OF SYMBOLS
A Design horizontal seismic coefficient
DL Dead load
E Modulus of elasticity
EQ Earthquake load along x direction
EQ Earthquake load along y direction
h Height of the structure
h Height measure from the base of the building to floor i
LL Live load
n Number of stores in the building
Q Lateral force at floor i
R Response reduction factor
Sa/g Average response acceleration coefficient for rock or soil sites based on
Appropriate natural periods and damping of the structure
V Design seismic base shear
T Approximate fundamental period of vibration of the structure
W Seismic weight of the structure
W Seismic weight of floor i
Z Zone factor
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List of table
3
Table No. Topic Page No.
4.1 Specification of the building 25
5.1 bending moment of circular building strong beam 36
5.2 bending moment of circular building strong column 36
5.3 bending moment of rectangular building strong beam 37
5.4 bending moment of rectangular building strong column 37
5.5 shear force of rectangular building strong beam 38
5.6 shear force of rectangular building strong column 38
5.7 shear force of circular building strong beam 39
5.8 shear force of circular building strong column 39

List of figure
Serial no. Title Page no.
Figure 4.4(a) Circular building plan 19
Figure 4.4(b) Rectangular building plan 19
Figure 4.4(c) Front view of circular
building plan
20
Figure 4.4(d) Front view of rectangular
building plan
20
Figure 4.4(e) whole plan of the circular
building
21
Figure 4.4(f) whole plan of the
rectangular building
21
Figure 4.4(g) 3D circular building plan
of weak column and
strong beam section
22
Figure 4.4(h) 3D rectangular building
plan of weak column and
strong beam section
22
Figure 4.4(i) 3D rectangular building
plan of strong column and
weak beam section
23
Figure 4.4(j) 3D circular building plan
of strong column and
weak beam section
23
Figure 4.5(a) Difference in deflection of
slab and beam adjacent
25
Figure 4.5(b) Discretization of beam 25
Figure 4.6.3 Distribution of lateral
forces at different levels at
which the masses are
located.
28
Figure 5.1.1(a) plate load under all
loading in circular
building plan with strong
column and weak beam
Front side
39
Figure 5.1.1(b) plate load under all
loading in circular
building plan with strong
column and weak beam
back side
39
Figure 5.1.2(a) plate load under all
loading in circular
building plan with weak
39
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column and strong beam
Front side
Figure 5.1.2(b) plate load under all
loading in circular
building plan with weak
column and strong beam
back side
39
Figure 5.1.3(a) plate load under all
loading in rectangular
building plan with strong
column and weak beam
Front side
40
Figure 5.1.3(b) plate load under all
loading in rectangular
building plan with strong
column and weak beam
back side
40
Figure 5.1.4(a) plate load under all
loading in rectangular
building plan with weak
column and strong beam
Front side
41
Figure 5.1.4(b) plate load under all
loading in rectangular
building plan with weak
column and strong beam
back side
41
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Contents
Chapter No. Topic Page No.
i List of figures
ii List of tables
iii List of symbols
iv Abstract
1 Introduction 7
1.1 General 8
1.2 Architectural behaviour of building 9
1.3 StaadPRO 10
2 Objective 12-13
3 Literature review 14-18
4 Methodology 19
4.1 Introduction 20
4.2 Purpose 20
4.3 Models of building 20
4.4 Description of building model 21-26
4.5 Slab and structural wall modelling 27
4.6 Loading 28-30
4.7 Load combination 30
4.8 Analysis method of structures 31-34
5 Results 35
5.1 Linear static analysis 36-42
6 Scope of future study 43-44
7 Conclusion 45-46
8 reference 47-48
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Chapter 1
Introduction
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Introduction
1.1General
An earthquake also known as quake or tremor is the result of a sudden release of
energy in the earth’s crust that creates seismic waves. The most important cause from
an engineering point of view, it is believed at present, is the movement of faults which
are buried deep below the earth surface.
Earthquake has always been a thread to human civilization from the day of its
existence, devastating human lives, properly and manmade structures. The very recent
earthquake that we faced in our neighbouring country Nepal has again shown nature’s
fury, causing such a massive destruction to the country and its people. It is such an
unpredictable calamity that it is very necessary for survival to ensure the strength to
the structures against seismic forces. Therefore, there is a continuous research work
going on around the world, resolving around development of new and better
techniques to resist the damages during seismic against failures under seismic forces it
is a prerequisite.
Earthquake cause ground to vibrate and these results a lateral forces on the surface.
Earthquakes don’t kill people but poorly built buildings do. Poorly built buildings
include poor quality of materials used poor shape of the buildings and poor design
without considering the codal provisions. Several countries including India have
experienced severe losses in the past, in terms of human casualty and property; most
recent are the bhuj earthquake of 26th January, 2001; Sumatra earthquake of 26th
December, 2004 leading to tsunami and Kashmir earthquake of 8th October, 2005.
Most of the casualties were due to collapse of poorly constructed buildings in the
seismically vulnerable regions.
Earthquake caused random ground motions, in all possible direction emanating from
the epicentre. Vertical ground motions are rare, but an earthquake is always
accompanied with horizontal ground shaking. The ground vibration causes the
structures resisting on the ground to vibrate, developing inertial forces in the structure.
As the earthquake changes directions, it can cause reversal of stresses in the stresses
in the structural components that is tension may change to compression and
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compression change to tension. Earthquake can cause generation of high stresses,
which can lead to yielding of structures and large deformation, rendering the structure
non-functional and unserviceable. Earthquake is a natural phenomenon which can
generate the most destructive forces on structure. In the present study, four different
models with different dimension of column and beams without shear wall constructed
on soft rocky soil in seismic zone v of India (as per IS: 1893-2016) are considered.
Linear and non linear static analysis using the software in STADPRO is carried out
for strong column-weak beam, weak column-strong beam and balance column-beam
considering without the effect of shear wall of round and rectangular. The objective of
the present study is to study the behaviour and comparison of rectangular and round
building with weak column-strong beam, strong column-weak beam and balanced
column-beam. Shear wall is one of the most commonly used lateral loads resisting in
high rise buildings.
1.2 Architectural behaviour of a building
Sometimes the shape of the building catches the eye of visitor, sometimes the
structural system appeals, and in other occasions both shape and structural system
work together to make the structure a Marvel. If the building is irregularly shape there
will be excessive deflection and twisting moment during earthquake. The architectural
problem includes the different aesthetically good looking structure with irregularities.
The irregularity may be plan or vertical irregularity, this includes soft storey.
Reinforced concrete frames are the most common practices in India, with increasing
number of high-rise structure adding up to the landscape. There are many important
Indian cities that fall in highly active seismic zones. Such high-rise structures,
constructed especially in highly prone seismic zones, should be analysed and designed
for ductility and should be designed with extra lateral stiffening system to improve
their seismic performance and reduce damages. Two of the most commonly used
lateral stiffening systems that can be used in buildings to keep the deflections under
limits are bracing system and shear wall.
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1.3 StaadPro
STAAD or (STAADPro) is a structural analysis and design software application
originally developed by Research Engineers International in 1997. In late 2005,
Research Engineers International was bought by Bentley Systems.
STAADPro is one of the most widely used structural analysis and
design software products worldwide. It supports over 90 international steel, concrete,
timber & aluminium design codes.
It can make use of various forms of analysis from the traditional static analysis to
more recent analysis methods like p-delta analysis, geometric non-linear analysis,
Pushover analysis (Static-Non Linear Analysis) or a buckling analysis. It can also
make use of various forms of dynamic analysis methods from time history analysis to
response spectrum analysis. The response spectrum analysis feature is supported for
both users defined spectra as well as a number of international code specified spectra.
Analytical Modelling
Analytical model can be created using the ribbon-based user interface, by editing the
command file or by importing several other files types like dxf, cis/2 etc. The model
geometry can even be generated from the data of macro-enabled applications (like
Microsoft Excel, Micro station etc.) by using Macros.
Physical Modelling
Physical modelling has been a significant feature included in the program. StaadPro
Physical Modeller takes advantage of physical modelling to simplify modelling of a
structure, which in turn more accurately reflects the process of building a model.
Beams and surfaces are placed in the model on the scale of which they would appear
in the physical world. A column may span multiple floors and a surface represents an
entire floor of a building, for example. A joint is then generated anywhere two
physical objects meet in the model (as well as at the free ends of cantilevered
members, for convenience).
STAAD Building Planner
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STAAD Building Planner is a module that enables seamless generation of building
models that can be analyzed and designed thereafter in the program itself. Operations
like defining geometry, making changes in the geometric specifications are matters of
only few clicks in this workflow.
Advanced Concrete Design
The Advanced Concrete Design workflow provides direct access for STAAD.Pro
models to leverage the power of the RCDC application. This is a standalone
application, which is operated outside the STAAD.Pro environment, but requires a
model and results data from a suitable analysis. The model should typically be formed
from beams and columns (plates are currently not supported). RCDC can be used to
design the following objects: Pile Caps, Footings, Columns and walls, Beams, Slabs.
As the projects progresses, each design created in RCDC is retained and displayed
when RCDC is re-entered, so that previous designs can be recalled and/or continued.
Detailed drawings and BBS of excellent quality can be generated as required and they
are quite ready to be sent for execution.
Advanced Slab Design
The StaadPro Advanced Slab Design workflow is an integrated tool that works from
within the StaadPro environment. Concrete slabs can be defined, and the data can be
transferred to RAM Concept. The data passed into RAM Concept includes the
geometry, section and material properties, loads and combination information, and
analysis results.
Earthquake Mode
Euro code 8: Part 1 contains specific requirements and recommendations for building
structures that are to be constructed in seismic regions. Essentially, these fundamental
requirements have been provided to ensure that the structures can sustain the seismic
loads without collapse and also – where required– avoid suffering unacceptable
damage and can continue to function after an exposure to a seismic event. This
StaadPro workflow is used to check if the structure conforms to the basic geometric
recommendations made in Euro code 8 (EC8). This workflow is in addition to the
normal post-processing workflow which gives the various analysis results.
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Chapter 2
Objective
12