G+10 L-Shaped Residential Building Seismic
Analysis
B.Tech. Thesis
By
Dipanjan Mondal (34901320033)
Manasija Haldar (34901320036)
Utsab Das
(34901321043)
Priyamjit Das
(34901321044)
Department of
Civil Engineering
COOCHBEHAR GOVERNMENT ENGINEERING
COLLEGE, COOCHBEHAR
JUNE, 2024
G+10 L-Shaped Residential Building Seismic
Analysis
A THESIS
Submitted in partial fulfillment of the
requirements for the award of the degree
of
Bachelor of Technology
By
DIPANJAN MONDAL
MANASIJA HALDAR
UTSAB DAS
PRIYAMJIT DAS
(34901320033)
(34901320036)
(34901321043)
(34901321044)
Department of Civil Engineering
COOCHBEHAR GOVERNMENT ENGINEERING COLLEGE,
COOCHBEHAR
JUNE, 2024
COOCH BEHAR GOVT. ENGINEERING COLLEGE,,
COOCH BEHAR
CANDIDATE’S DECLARATION
I hereby certify that the work which is being presented in the thesis entitled G+10 in the partial
fulfillment of the requirements for the award of the degree of MASTER OF TECHNOLOGY and submitted
in the DISCIPLINE OF < NAME OF THE DISCIPLINE>, Indian Institute of Technology Indore, is an
authentic record of my own work carried out during the time period from <Month and year of joining the
B.tech. program> to < Month and year of B.tech. Thesis submission> under the supervision of <Name of the
Supervisor of B.tech. thesis #1, Designation, and Affiliation> and < Name of the Supervisor of B.tech. thesis
#2, Designation, and Affiliation>
The matter presented in this thesis has not been submitted by me for the award of any other degree of
this or any other institute.
Signature of the student with the date
(NAME OF THE B.TECH. STUDENT)
---------------------------------------------------------------------------------------------------------------------------This is to certify that the above statement made by the candidate is correct to the best of my/our
knowledge.
Signature of the Supervisor of
Signature of the Supervisor of
B.tech. thesis #1 (with date)
B.tech. thesis #2 (with date)
(NAME OF SUPERVISOR)
(NAME OF SUPERVISOR)
-------------------------------------------------------------------------------------------------------------------------------<NAME OF THE B.tech. STUDENT> has successfully given his/her B.tech. Oral Examination held
on <Date of B.tech. Oral Examination>.
Signature(s) of Supervisor(s) of B.tech. thesis
Date:
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CHAPTER 1
1.1 Introduction
The opinion that designing new buildings to be Earthquake resistant will cause substantial additional costs is
still among the constructional professionals. In a country of moderate seismicity adequate seismic resistance
of new buildings may be achieved at no or no significant additional cost however the expenditure needed to
ensure adequate seismic resistance may depend strongly on the approach selected during the conceptual design
phase and the relevant design method. Regarding the conceptual design phase early collaboration between the
architect and civil engineering is crucial. Concerning the design method it should be stated that significant
progress has been made recently. Intensive research has improved the understanding of the behaviour of a
building or structure during an earthquake and resulted in the development of more efficient and modern design
methods.
The Advantages Of The Modern Method:
• Drastic reduction in the seismic design Forces at ultimate limit state.
Better resistance against collapse.
Good deformation control
Prevention of damage for earthquake up to a chosen intensity (damage limit state earthquake)
Larger flexibility in case of changes in building use.
Practically equal costs.
The last three advantages are particularly important to the building owner.
The 2001 Gujarat earthquake is a recent example of catastrophe. It was the first major earthquake to hit an
urban area of India in the last 50 years. It Killed 13,800 people, Injured 167,000 and a large number of
reinforced concrete multi-storeyed frame buildings were heavily damaged and many of them were collapsed
completely in the towns of Kachchh district. Destruction total estimated to be about US$ 5billion.It is tempting
to think that this risk concentrated only in areas of high seismicity but this reasoning does not hold. In regions
of low to moderate seismicity can be predominant risk as well. Buildings that are very vulnerable and at risk
from even a relatively weak earthquake continue to built today. Still for new buildings the basic principles of
earthquake resistant design and also the basic earthquake specifications of building codes are not followed.
The reason is unawareness, convenience or intentional ignorance. As a result the earthquake risk continues to
increase unnecessarily. The opinion that designing new buildings to be earthquake resistant will cause
substantial additional costs is still common among construction professionals. Moreover appropriate official
controls and checks are lacking.
The recent earthquakes in the past have indicated the need of awareness that we need to incorporate for a new
construction, retrofitting of existing structures and general safety.
Over the centuries, many researchers have come to a conclusion that earthquakes don’t kill people; buildings
do. Earthquake does cause buildings, bridges and other structures to experience sudden lateral acceleration but
this solely is not responsible for their collapse. Many experts now believe we Can get rid of this fearsome
temblor through earthquake-resistant buildings which can prevent the Total collapse and preserve life. Today,
the sciences of building earthquake-resistant structures have Advanced tremendously and many developed
countries have been practicing this approach There Are tremendous techniques from base isolation and
damping process to resistant design techniques.In a developing country, expensive technology is quite difficult
to incorporate whereas simple Techniques which deal with the basic principles can be followed without any
harsh investment.
Before approaching these techniques it’s also equally essential to understand earthquakes. Earthquakes do
occur when tectonic plates move and rub against each other. The case becomes extreme when large earthquakes
may hit sometimes as a result of this movement. They snap and rebound to their original position which is also
coined as Elastic Rebound Theory. When this earthquake’s ground motion occurs beneath a building and it is
strong enough, it sets the building in motion, starting with the building foundation, and transfers the motion
throughout the rest of building in a very complex way. These motions in turn induce forces which can produce
damage.
Our concern is to make our structure withstand such forces. Every building must withstand significant lateral
force. We need to give our attention while designing the plan, section of a building, selecting the construction
material and while implementing the ideas in the construction phase. There are tremendous techniques that
can be embraced by a normal building. When dispatching the forces toward the footing from the structure,
columns play a vital role than that of the beams so designing a structure with strong columns than beams is
appreciated.
Structure might be of various shapes but for earthquake-resistant design, a simple and regular shape such as
rectangular can be beneficial. Shear wall is a best walling system for earthquake-resistant buildings but it can
be a bit expensive. In such cases, cross-bracing can be provided which also helps in dispatching the forces with
great efficiency. While considering height of the building, the floor area and the overall width of the area must
be in a decreasing form as stories increase. As all the load will be transferred to a base column, so the width
of base column should also be properly reinforced. Proper spacing must be maintained between two buildings.
Simple but good plans are always appreciated and are good to resist earthquake.
When stirrups are being bent for beams and columns, proper locking at the edge with at least 45 degree must
be maintained as they form good bonding and resist the buckling phenomenon. Proper space between the bars
to facilitate during concrete compaction, the interlocking of two beams with proper development length and
mix design of concrete are also major considering point during the construction phase. Footing as per the soil
condition must be identified and proper placing of footing must be done. Horizontal truss for the roofing system
can be best choice in normal building. Identifying the safe region of a building can be beneficial at the time of
emergency. Moreover obeying a country building code and getting assistance of experts can have great
advantage.
Proper selection of material for construction also plays a vital role. More economical material which is locally
available, extracted from renewable resources can be eco-friendly in the construction and also add up
tremendous aesthetical benefits. Light material can be used which makes the structure more strong in a nonload bearing structure. Retrofitting for existing structure in accordance with code can make the pre-existing
structure safe. Being aware about the catastrophe well in advance is one of the means to get rid of the problems
and implementing the safety in need and save lives.
1.2 Scope of project
Study Area : COOCHBEHAR
The Indian subcontinent has a history of devastating earthquakes with 59% of the land being vulnerable to
earthquakes. The Indian plate is driving Asia at a rate of approximately 47 mm/year. Intra plate earthquakes
from Himalayan region and inter plate earthquakes of local origin are the major reasons for seismic design of
buildings. And due to earthquake:

Structures in to and fro motion develop stresses due to inertial force(NFL)

Vertical shaking adds or subtracts to weight of structure.

These lateral inertia forces are transferred by the floor slab to the walls or columns, to the foundations,
and finally to the soil system underneath. This sometimes leads to settlement of foundation due to soil
liquefaction.
Thus, there is an enormous need to establish a Seismic Disaster management plan for India which can only be
done through analysis and modelling of structures. Modelling and simulation of structural components and
complex structures through software's is the most sophisticated way of analysis.
Computers can perform complicated computations at a high speed therefore computer programs are used for
analysis and design of structural member. Hand computations are applicable for small problem and tedious for
even for medium sized calculations and 3-D analysis is almost impossible. On the other hand in computer
analysis 3-D analysis can be easily performed with a high degree of accuracy, STAAD Pro connect edition
is a very powerful which can be used for 3-D analysis and is useful for analysis and design of multi-storied
buildings. Full range of analysis including static, P-delta, response spectrum, time-history, cable etc. and steel
design, concrete design and timber design is available in STAAD Pro.
1.3 Objective of project
Seismic analysis of different prototype of RCC building was selected. Prototypes were having various
dimensions of beams and columns. These were analysed through STAAD pro connect edition for same load
combinations..
Buildings were analysed for:
Lenier static Base share calculation
Time history Base shear calculation
And 6 mode shapes were generated and various reactions and forces were calculated.
CHAPTER 2
2.1 Measuring the size of an earthquake
Earthquakes range broadly in size. A rock-burst in an Idaho silver mine may involve the fracture of 1 meter of
rock; the 1965 Rat Island earthquake in the Aleutian arc involved a 650 kilometre length of the Earth's crust.
Earthquakes can be even smaller and even larger. If an earthquake is felt or causes perceptible surface damage,
then its intensity of shaking can be subjectively estimated. But ma ny large earthquakes occur in oceanic areas
or at great focal depths and are either simply not felt or their felt pattern does not really indicate their true size.
Today, state of the art seismic systems transmit data from the seismograph via telephone line and satellite
directly to a central digital computer. A preliminary location, depth-of-focus, and magnitude can now be
obtained within minutes of the onset of an earthquake. The only limiting factor is how long the seismic waves
take to travel from the epicentre to the stations usually less than 10 minutes.
Magnitude:
Modern seismographic systems precisely amplify and record ground motion (typically at periods of between
0.1 and 100 seconds) as a function of time. This amplification and recording as a function of time is the source
of instrumental amplitude and arrival-time data on near and distant earthquakes. Although similar
seismographs have existed since the 1890's, it was only in the 1930's that Charles F. Richter, a California
seismologist, introduced the concept of earthquake magnitude. His original definition held only for California
earthquakes occurring within 600 km of a particular type of seismograph (the Woods-Anderson torsion
instrument). His basic idea was quite simple: by knowing the distance from a seismograph to an earthquake
and observing the maximum signal amplitude recorded on the seismograph, an empirical quantitative ranking
of the earthquake's inherent size or strength could be made. Most California earthquakes occur within the top
16 km of the crust; to a first approximation, corrections for variations in earthquake focal depth were, therefore,
unnecessary.
Richter's original magnitude scale (M) was then extended to observations of earthquakes of any distance and
of focal depths ranging between 0 and 700 km. Because earthquakes excite both body waves, which travel into
and through the Earth, and surface waves, which are constrained to follow the natural wave guide of the Earth's
uppermost layers, two magnitude scales evolved - the my and Mescales.
The standard body-wave magnitude formula is
Mb = log10(A/T)+Q(D,h),
Where A is the amplitude of ground motion (in microns); Tis the corresponding period (in
seconds); and Q(D,h) is a correction factor that is a function of distance, D (degrees), between
epicentre and station and focal depth, h (in kilometres), of the earthquake. The standard surfacewave formula is
Ms = log10 (A/T) +1.66 log10 (D) + 3.30.
There are many variations of these formulas that take into account effects of specific
geographic regions, so that the final computed magnitude is reasonably consistent with Rispecifi
original definition of M. Negative magnitude values are permissible.
A rough idea of frequency of occurrence of large earthquakes is given by the following table:
This table is based on data for a recent 47 year period. Perhaps the rates of earthquake occurrence are highly
variable and some other 47 year period could give quite different results.
The original m, scale utilized compression body P-wave amplitudes with periods of 4-5 s, but recent
observations are generally of 1 s-period P waves. The Ms scale has consistently used Rayleigh surface waves
in the period range from 18 to 22 s.
When initially developed, these magnitude scales were considered to be equivalent; in other words,
earthquakes of all sizes were thought to radiate fixed proportions of energy at different periods. But it turns
out that larger earthquakes, which have larger rupture surfaces, systematically radiate more long-period energy.
Thus, for very large earthquakes, body-wave magnitudes badly underestimate true earthquake size; the
maximum body-wave magnitudes are about 6.5 6.8. In fact, the surface-wave magnitudes underestimate the
size of very large earthquakes; the maximum observed values are about 8.3-8.7. The mostly damage to
structure is caused by the energy for shorter period.
Energy, E
The amount of energy radiated by an earthquake is a measure of the potential for damage to man-made
structures. Theoretically, its computation requires summing the energy flux over a broad suite of frequencies
generated by an earthquake as it ruptures a fault. Because of instrumental limitations, most estimates of energy
have historically relied on the empirical relationship developed by Beno Gutenberg and Charles Richter:
log10E 11.8+1.5M5
Where energy, E, is expressed in ergs. The drawback of this method is that Ms is computed from a bandwidth
between approximately 18 to 22 s. It is now known that the energy radiated by an earthquake is concentrated
over a different bandwidth and at higher frequencies. With the worldwide deployment of modern digitally
recording seismograph with broad bandwidth response, computerized methods are now able to make accurate
and explicit estimates of energy on a routine basis for all major earthquakes. A magnitude based on energy
radiated by an earthquake, Me, can now be defined,
Me2/3 log10E - 2.9.
For every increase in magnitude by 1 unit, the associated seismic energy increases by about 32
times.
Although Mw, and Me are both magnitudes, they describe different physical properties of the
earthquake. Mw, computed from low-frequency seismic data, is a measure of the area ruptured by
an earthquake. Me, computed from high frequency seismic data, is a measure of seismic potential
for damage. Consequently, Mw, and Me. often do not have the same numerical value.
Intensity
The increase in the degree of surface shaking (intensity) for each unit increase of magnitude of a shallow
crustal earthquake is unknown. Intensity is based on an earthquake’s local accelerations and how long these
persist. Intensity and magnitude thus both depend on many variables that include exactly how rock breaks and
how energy travels from an earthquake to a receiver. These factors make it difficult for engineers and others
who use earthquake intensity and magnitude data to evaluate the error bounds that may exist for their particular
applications.
An example of how local soil conditions can greatly influence local intensity is given by catastrophic damage
in Mexico City from the 1985, Ms 8.1 Mexico earthquake cantered some 300 km away. Resonances of the
soil-filled basin under parts of Mexico City amplified ground motions for periods of 2 seconds by a factor of
75 times. This shaking led to selective damage to buildings 15-25 stories high (same resonant period), resulting
in losses to buildings of about $4.0 billion and at least 8,000 fatalities.
The occurrence of an earthquake Is a complex physical process. When an earthquake occurs, much of the
available local stress is used to power the earthquake fracture growth to produce heat rather that to generate
seismic waves. Of an earthquake systems total energy, perhaps 10 percent to less that 1 percent is ultimately
radiated as seismic energy. So the degree to which an earthquake lowers the Earth’s available potential energy
is only fractionally observed as radiated seismic energy.
2.2 Types of Earthquake Measurement Scales:
The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures
the effects of an earthquake, and is distinct from the moment magnitude usually reported for an earthquake
(sometimes misreported as the Richter magnitude), which is a measure of the energy released. The intensity
of an earthquake is not totally determined by its magnitude.
The scale quantifies the effects of an earthquake on the Earth’s surface, humans, objects of nature, and manmade structures on a scale from I (not felt) to XII (total destruction). [1] [2] Values depend upon the distance
to the earthquake, with the highest intensities being around the epicentral area.
The Richter magnitude scale (often shortened to Richter scale) was developed to assign a single number to
quantify the energy released during an earthquake.
The scale is a base-10 logarithmic scale. The magnitude is defined as the logarithm of the ratio of the amplitude
of waves measured by a seismograph to arbitrary small amplitude.
The moment magnitude scale (abbreviated as MMS; denoted as Mw or M) is used by seismologists
To measure the size of earthquakes in terms of the energy released. [1] The magnitude is based on
The seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average
amount of slip on the fault and the size of the area that slipped.[ The symbol for the moment magnitude scale
is with the subscript meaning mechanical work accomplished. The moment magnitude is a dimensionless
number
defined
by
INTRODUCTION:-
Our project involves analysis and design of multi-storeyed [G + 10] using a very popular designing software
STAAD Pro. We have chosen STAAD Pro because of its following advantages:
i) easy to use interface
ii) conformation with the Indian Standard Codes
iii)versatile nature of solving any type of problem
iv) Accuracy of the solution.
STAAD.Pro features a state-of-the-art user interface, visualization tools, powerful analysis and design engines
with advanced finite element and dynamic analysis capabilities. From model generation, analysis, and design
to visualization and result verification, STAAD.Pro is the professional‟s choice for steel, concrete, timber,
aluminum and cold-formed steel design of low and high-rise buildings, culverts, petrochemical plants, tunnels,
bridges, piles and much more.
STAAD.Pro consists of the following:
The STAAD.Pro Graphical User Interface: It is used to generate the model, which can then be analyzed using
the STAAD engine. After analysis and design is completed, the GUI can also be used to view the results
graphically. The STAAD analysis and design engine: It is a general-purpose calculation engine for structural
analysis and integrated Steel, Concrete, Timber, and Aluminium design. To start with we have solved some
sample problems using STAAD Pro and checked the accuracy of the results with manual calculations. The
results were to satisfaction and were accurate. In the initial phase of our project, we did calculations regarding
loadings on buildings and also considered seismic and wind loads. Structural analysis comprises the set of
physical laws and mathematics required to study and predict the behavior of structures. Structural analysis can
be viewed more abstractly as a method to drive the engineering design process or prove the soundness of a
design without dependence on directly testing it. The aim of design is the achievement of an acceptable
probability that the structures being designed will perform satisfactorily during their intended life. With an
appropriate degree of safety, they should sustain all the loads and deformations of normal construction and
use, and have adequate durability and adequate resistance to the effects of seismic, and wind. Structure and
structural elements shall normally be designed by Limit State Method. Account should be taken of accepted
theories, experiments and experience and the need to design for durability. Design, including design for
durability, construction, and use in service should be considered as a whole. The realization of design
objectives requires compliance with clearly defined standards for materials, production, workmanship, and
also maintenance and use of structure in service. The design of the building is dependent upon the minimum
requirements as prescribed in the Indian Standard Codes. The minimum requirements about the structural
safety of buildings are being covered by way of laying down minimum design loads which have to be assumed
for dead loads, imposed loads, and other external loads, the structure would be required to bear. Strict
conformity to loading standards recommended in this code, it is hoped, will not only ensure the structure safety
of the building which is being designed
LOAD CONSIDERED
2.1 DEAD LOADS [ IS 875 ( part -1 ) : 1987 ]
All permanent constructions of the structure form the dead loads. The dead load comprises of the
weights of walls, partitions floor finishes, false ceilings, false floors, and the other permanent constructions in
the buildings. The dead load loads may be calculated from the dimensions of various members and their unit
weights. the unit weights of plain concrete and reinforced concrete made with sand and gravel or crushed
natural stone aggregate may be taken as 24 kN/m” and 25 kN/m” respectively.
2.2 IMPOSED LOADS [ IS 875 ( part -2 ) : 1987 ]
Imposed load is produced by the intended use or occupancy of a building including the weight of
movable partitions, distributed and concentrated loads, load due to impact and vibration and dust loads.
Imposed loads do not include loads due to wind, seismic activity, snow, and loads imposed due to temperature
changes to which the structure will be subjected to, creep and shrinkage of the structure, the differential
settlements to which the structure may undergo.
2.3 WIND LOAD [ IS 875 ( part -3 ) : 2015 ]
The wind is air in motion relative to the surface of the earth. The primary cause of wind is traced
to the earth‟s rotation and differences in terrestrial radiation. The radiation effects are primarily responsible
for convection either upwards or downwards. The wind generally blows horizontal to the ground at high wind
speeds. Since vertical components of atmospheric motion are relatively small, the term „wind‟ denotes almost
exclusively the horizontal wind, vertical winds are always identified as such. The wind speeds are assessed
with the aid of anemometers or anemographs which are installed at meteorological observatories at heights
generally varying from 10 to 30 metres above ground. Design Wind Speed (V,) The basic wind speed (V,) for
any site shall be obtained from and shall be modified to include the following effects to get design wind
velocity at any height (V,) for the chosen structure:
a) Risk level;
b) Terrain roughness, height, and size of structure; and
c) Local topography. It can be mathematically expressed as follows:
Where: V = Vb * kl * k2* k3*k4
Vb = design wind speed at any height z in m/s;
kl = probability factor (risk coefficient) ( clause no- 6.3.1)
k2 = terrain, height and structure size factor and ( clause no- 6.3.2)
k3 = topography factor ( clause no- 6.3.3)
k4 = importance factor for cyclonic region ( clause no-6.3.4)
Risk Coefficient (kI Factor) gives basic wind speeds for terrain Category 2 as applicable at 10 m above ground
level based on 50 years mean return period. In the design of all buildings and structures, a regional basic wind
speed having a mean return period of 50 years shall be used .
Terrain, Height and Structure Size Factor (k2 Factor)
Terrain - Selection of terrain categories shall be made with due regard to the effect of obstructions
which constitute the ground surface roughness. The terrain category used in the design of a structure may vary
depending on the direction of wind under consideration. Wherever sufficient meteorological information is
available about the nature of wind direction, the orientation of any building or structure may be suitably
planned.
Topography (k3 Factor) The basic wind speed Vb takes account of the general level of site above sea level. This
does not allow for local topographic features such as hills, valleys, cliffs, escarpments, or ridges which can
significantly affect wind speed in their vicinity. The effect of topography is to accelerate wind near the summits
of hills or crests of cliffs, escarpments, or ridges and decelerate the wind in valleys or near the foot of cliff,
steep escarpments, or ridges.
Importance Factor for Cyclonic Region (k4)
The east coast of India is relatively more vulnerable for occurrences of severe cyclones. On the west coast,
Gujarat is vulnerable for severe cyclones. Studies of wind speed and damage to buildings and structures point
to the fact that the speeds given in the basic wind speed map are often exceeded during the cyclones. The effect
of cyclonic storms is largely felt in a belt of approximately 60 km width at the coast. In order to ensure better
safety of structures in this region (60 km wide on the east coast as well as on the Gujarat Coast), the following
values of k₁ (as recommended in IS 15498) are stipulated as applicable according to the importance of the
structure:
K4
Structures of post-cyclone importance for emergency services (such as cyclone shelters,
1.30
hospitals, schools, communication towers, etc)
Industrial structures
1.15
All other structures
1.00
WIND PRESSURES AND FORCES ON BUILDINGS/STRUCTURES:
The wind load on a building shall be calculated for: a) The building as a whole, b) Individual
structural elements as roofs and walls, and c) Individual cladding units including glazing and their fixings.
Pressure Coefficients - The pressure coefficients are always given for a particular surface or part of the surface
of a building. The wind load acting normal to a surface is obtained by multiplying the area of that surface or
its appropriate portion by the pressure coefficient (C,) and the design wind pressure at the height of the surface
from the ground. Then the wind load, F, acting in a direction normal to the individual structural element or
Cladding unit is:
F= (Cpe – Cpi) A Pd
Where,
Cpe = external pressure coefficient,
Cpi = internal pressure- coefficient,
A = surface area of structural or cladding unit, and
Pd = design wind pressure element
2.4 SEISMIC LOAD Design Lateral Force The design lateral force shall first be computed for the building as
a whole. This design lateral force shall then be distributed to the various floor levels. The overall design seismic
force thus obtained at each floor level shall then be distributed to individual lateral load resisting elements
depending on the floor diaphragm action.
Design Seismic Base Shear
The total design lateral force or design seismic base shear (Vb) along any principal direction shall be
determined by the following expression:
Vb = Ah W
Where, Ah = horizontal acceleration spectrum W = seismic weight of all the floors
Fundamental Natural Period
The approximate fundamental natural period of vibration (T,), in seconds, of a momentresisting frame
building without brick in the panels may be estimated by the empirical expression:
Ta=0.075 h0.75 for RC frame building
Ta=0.085 h0.75 for steel frame building
Where,
h = Height of building, in m. This excludes the basement storeys.
Ta= The approximate fundamental natural period of vibration (T,) in seconds.
Expression:
T=.09H/ D
Where, h= Height of building
d= Base dimension of the building at the plinth level, in m, along the considered direction of the lateral
force.
Distribution of Design Force
Vertical Distribution of Base Shear to Different Floor Level The design base shear (V) shall be
distributed along the height of the building as per the following expression:
Qi=Design lateral force at floor i
, Wi =Seismic weight of floor i,
Hi =Height of floor i measured from base,
and n=Number of storeys in the building is the number of levels at which the masses are located
Dynamic Analysis
Dynamic analysis shall be performed to obtain the design seismic force, and its distribution to different
levels along the height of the building and to the various lateral load resisting elements, for the following
Buildings:
a) Regular buildings -Those greater than 40 m in height in Zones IV and V and those Greater than 90 m in
height in Zones II and 111.
b) Irregular buildings – All framed buildings higher than 12m in Zones IV and V and those greater than 40m
in height in Zones 11 and III.
The analytical model for dynamic analysis of buildings with unusual configuration should be such that it
adequately models the types of irregularities present in the building configuration. Buildings with plan
irregularities cannot be modelled for dynamic analysis. For irregular buildings, lesser than 40 m in height in
Zones 11and III, dynamic analysis, even though not mandatory, is recommended. Dynamic analysis may be
performed either by the Time History Method or by the Response Spectrum Method. However, in either
method, the design base shear (VB) shall be compared with a base shear (VB)
Time History Method
Time history method of analysis shall be based on an appropriate ground motion and shall be performed
using accepted principles of dynamics.
Load calculation and analysis
Dead load (as per IS 875-1987 part 1)
Dead loads, also known as permanent or static loads, are those that remain
relatively constant over time and comprise, for example, the weight of a building's
structural elements, such as beams, walls, roof and structural flooring components.
§Structural self-weight
§Brickwork –
ØBrick masonry with engineering bricks of density 21.20 KN/m
ØPlastering of 20mm total thickness of density 20.40 KN/m
3
Table – 1, pg - 6
3
Table – 1, pg - 10
Now for 230mm thick masonry wall + 20 mm plaster (Total assumed plaster on
wall), loading shall be 0.23 x 21.20 + 0.02 x 20.40 = 5.284 KN/m per m height.
FLOOR
WALL HEIGHT
UDL ON BEAM (KN/M)
G+10
3-0.3=2.7
13.5732
Assuming 25% wall area in windowed walls, the UDL on respective beams
FLOOR
UDL ON BEAM HAVING WINDOWED WALL (KN/m)
G+ 10
13.5732* 0.75 = 10.1799
§Flooring /ceiling –
ØFloor finish – Tiles of 0.83 KN/m
2
+ plaster of 0.25 KN/m
2
2
= 1.08 KN/m .
[ Table - 2, pg - 30]
ØCeiling – Plaster on concrete @ 0.25 KN/m².
[Table - 2, pg - 29 ]
ØRoofing - Mortar Screeding of 150 mm thickness @ 0.21 KN/m².
[ Table – 2, pg - 31 ]
So, Ground floor slabs’ load = 1.08 KN/m
th
Upto 9
2
floor slabs’ load = 1.08+0.25 = 1.33 KN/m
Roof slabs’ load = 0.25+0.21 = 0.46 KN/m
2
2
Live load (as per IS 875-1987 part 2)
Live load is what is produced during the use of the structure. It is also
called imposed load
Imposed floor loads
(CL 3.1, 3.1.1, 4.1.1)
2
ØAll rooms and kitchens - 2 kN/m
2
ØToilet and bath rooms – 2 kN/m
2
ØStaircases – 3 kN/m
Imposed loads on roofs (Rain load is not included)
(CL 4.1)
2
ØFlat roof with access provided – 1.5 kN/m
2
ØFlat roof with access not provided – 0.75 kN/m
Wind load (IS 875 part 3 : 2015)
Basic wind speed (VB) = 47 m/s (for Coochbeher region)
CL 6.2
Terrain category = 2 (for terrain with numerous high closely spaced obstructions)
CL 6.3.2.1
Risk Coefficient/Probability factor (k1) = 1 (for all general buildings and structures)
CL 6.3.1
Topography Factor (k3) = 1 (for flat land having upwind slope < 3 degrees)
CL 6.3.3
Importance factor for cyclonic region (K4) = 1 (for all general structures)
CL 6.3.4
Wind directionality factor (Kd) = 1 (for cyclone affected regions)
Cl 7.2.1
Area averaging factor (Ka) = 0.9 (interpolated value for 15m^2 tributary area)
CL7.2.2
Combination factor (Kc) = 0.9
CL 7.3.3.13
Design Wind Speed, Vz = K1*K2*K3*K4*Vb
CL 6.3
Wind Pressure, Pz = 0.6*Vz^2 CL 7.2
Design Wind Pressure, Pd = Pz*Ka*Kd*Kc
Height
CL 7.2
Terrain and height
Wind
multiplier (K2)
pressure
CL.6.3.2.2
(Pz) N/m2
P
(kN/m2)
0.7*Pz
(kN/m2)
Pd max of 0.7Pz
and P (kN/m2)
10
1
1325.4
1.073574 0.928
1.074
15
1.05
1461.3
1.184
1.023
1.184
20
1.07
1517.5
1.229
1.062
1.229
30
1.12
1662.6
1.347
1.164
1.347
50
1.17
1814.3
1.470
1.270
1.470
METHODOLOGY
To accomplish the objectives of the project, the following steps have been given
below.
1. To prepare Plan & Elevation of G+ 9 Residential Building.
2. To Study the Physical Parameters of the Building
3. To study the different methods such as Seismic Coefficient Method & Moment
Resisting Method
4. To study the different IS Codes:
IS IS-456:200:DESIGN CODE FOR RCC STRUCTURES
IS-875(PART 1) 2015 :CODE FOR DEAD LOADS
IS-875(PART 2) 2015 :CODE FOR IMPOSED LOADS
IS-875(PART 3) 2015: CODE FOR WIND LOADS
5. To consider all the Moments and forces acting on the building according to their
zone.
6. To analyse and design the structure using STAAD.PRO and checking the result
manually.
7. To prepare conclusion of the result obtained.
+
PLAN AND ELEVATION OF A RESIDENTIAL BUILDING
CHAPTER 5
PHYSICAL PARAMETERS OF A BUILDING
5.1 Physical Parameters
1. Utility of building Residential building
2.No of storeys: G+10
3.Shape of the building L shaped.
4. Type of construction: R.C.C framed structure
5. Type of walls brick wall
5.2 Structural Model
1. Size of Column = 400 mm x 400 mm
2. Size of Beam 250 mm x 300 mm
3. Thickness of external wall = 0.23
4. Thickness of slab = 150mm (thick)
5. Live load on floor = 4 kN/m²
6. Self weightbDY 0.25x0.3x25-1.875 kN
7. Unit wt of Concrete 25 kN/m³
8. Unit wt of Mud phuska 20 kN/m³
9. Height of each storey = 3m
10.
Height from ground Floor to First floor = 3m
11.
Dead load on roof 6.75 kN/m²
12.
Dead load on floor = 4.75 kN/m²
13.
TYPES OF LOADING ON A STRUCTURE
Loading on tall buildings is different from low-rise buildings in many ways such as
large accumulation of gravity loads on the floors from top to bottom, increased
significance of wind loading and greater importance of dynamic effects. Thus,
multi-storeyed structures need correct assessment of loads for safe and
economical design. Except dead loads, the assessment of loads can not be done
accurately.
Live loads can be anticipated approximately from a combination of experience and
the previous field observations. Wind and earthquake loads are random in nature
and it is difficult to predict them. They are estimated based on a probabilistic
approach. Loads cause stresses, deformations, and displacements in structures.
Assessment of their effects is carried out by the methods of structural analysis.
Excess load or overloading may cause structural failure, and hence such possibility
should be either considered in the design or strictly controlled.
6.1 Gravity Loads
Dead loads due the weight of every element within the structure as well as live
loads that are acting on the structure when in service constitute gravity loads. The
dead loads are calculated from the member sizes and estimated material
densities. Live loads prescribed by codes are empirical and conservative based on
experience and accepted practice. The equivalent minimum loads for office and
residential buildings as per IS 875 are as specified in following Table as mentioned
below.
ABOUT SOFTWARES
This project is mostly based on software and it is essential to know the details
about these software’s.
List of software’s used
1. Staad pro(v8i)
2. Auto cad
A
10
Staad pro
Staad Foundation
Fig 10.1 Softwares
Auto Cad
20
10.1 Staad
Staad is powerful design software licensed by Bentley Staad stands for structural
analysis and design. Any object which is stable under a given loading can be
considered as structure. So first find the outline of the structure, where as analysis
is the estimation of what are the type of loads that acts on the beam and
calculation of shear force and bending moment comes under analysis stage. Design
phase is designing the type of materials and its dimensions to resist the load. This
we do after the analysis. To calculate shear force and bending moment diagram of
a complex loading beam it takes about an hour. So when it comes into the building
with several members it will take a week. Staad pro is a very powerful tool which
does this job in just an hour’s staad is a best alternative for high rise buildings.
Now a days most of the high rise buildings are designed by staad which makes a
compulsion for a civil engineer to know about this software.
10.1.1 Alternatives for staad:
Struts, robot, sap, which gives details clearly regarding reinforcement and
calculations.