Structural analysis and design of multi storey ppt
STRUCTURAL ANALYSIS AND DESIGN OF MULTI STOREY
Y s rohith kumar
Kanak d r
Under the guidance of:
Mr. bipin g k
The principal objective of the project is to gain the
idea of art and science of designing multi-
storeyed structure with economy, elegance,
safety, serviceability and durability.
It also deals with problems involved and to gain
ability over solving the problems.
This has been an excellent opportunity for us to
put into the engineering knowledge which has
been acquired during the curriculum.
LOCATING THE POSITIONS OF
COLUMNS AND BEAMS AND FIXING
Based on functionality and structural requirements, the
location and orientation of column and beam are decided.
In addition, the aesthetic point of view and parking
requirements in the basement were also considered while
fixing up the above locations.
Depth of columns and beams were fixed using l/d ratio and
The following loads were considered
for analysis and design of the
structure under consideration.
Dead loads of various types of wall are
The various imposed loads considered for
project are shown in table
MODELLING AND ANALYSIS
Creation of model
Defining end condition
Generation of wind and seismic load
Assigning of defined loads
Checking the model for errors
Running the analysis
To assess the dead loads and other external loads
and forces likely to be applied on the structure.
To determine the design loads from different
combinations of loads.
To estimate structural responses (bending moment,
shear force, axial thrust etc.) due to the design
To determine the cross-sectional areas of concrete
sections and amounts of reinforcement needed.
Limit State Method
Limit State Method is used in the design of this
structure as per the guidelines of IS-456:2000.
There are two main limit states:
Limit state of collapse and
Limit state of serviceability.
DESIGN OF FOOTING
1.The axial load and the moment at the bottom of the column are
2. A suitable safe bearing capacity of the soil is considered.
3. The area of footing is determined by equating the pressure below
footing to the SBC of soil.
4. The maximum and minimum pressure below footing is from the
pmax = P/A + Mxx/Zxx + Myy/Zyy <= SBC
Minimum Pressure, pmin = P/A - Mxx/Zxx - Myy/Zyy > 0
5. A suitable depth of footing (D) is assumed to satisfy the
two-way shear criteria and is checked against one-way
shear and bending moments. The maximum depth from the
above considerations is taken as the „depth of footing‟.
6. The reinforcement is determined from both one-way and
bending moment considerations and the maximum of the
two is provided along the length and breadth of the footing.
DESIGN OF COLUMN
1. Assume the percentage steel “p” between 0.8% and 4% and distribution of
reinforcement on all the four sides.
2. For the assumed cross section of the column calculate the values of d1/D,
p/fck and Pu/(fck*b*D). For these values obtain the moment carrying
capacities of the section about X and Y axis referring to charts in SP-16
(Chart 43, 44, 45, 46).
3. Referring to Chart 63 of SP 16, Puz/Ag is calculated corresponding to
values of p, fck and fy.
4. The ratios Pu/Puz, Mux/Mux1 and Muy/Muy1 are found. Then referring to
the Chart 64 of SP 16, permissible value of Mux/Mux1 is determined
corresponding to the values of Muy/Muy1 and Pu/Puz. If this criterion is not
satisfied, „p‟ is increased and the above procedure is repeated.
5. Based on the obtained steel percentage, Ast is calculated. The
diameter and the number of longitudinal bars are decided based
on the Ast obtained.
6. The lateral ties for the column are obtained from the following
The diameter of lateral ties should be greater of the following,
0.25 times diameter of main bar
The spacing of the lateral ties should be least of the
Least lateral dimension
16 times diameter of main bar
DESIGN OF BEAMS
Assume the depth of the beam.
Calculate the effective span (le) of the beam.
Calculate the loads.
Calculation of moments and shear force.
Check if the beams are under reinforced or over
Calculation of reinforcement, using Mu/bd2 and refer SP-
16 for pt value in order to obtain Ast.
Check for shear stress using τv=Vu/(bd)
from table 19 of IS:456-2000,obtain τc.
Check for deflection control.
DESIGN OF SLABS
1. Overall thickness of the slab is based on l/d ratio.
2. Loads for the design is taken from are IS: 875-1987 and
are factored as per IS: 456-2000.
3. Calculation of moment:
The moment values for one-way slab are obtained from
the principle of mechanics. The moment values for two-way
slab are obtained from the bending moment coefficients
available in table 26, page 91 of IS: 456-2000.
4. Flexural steel:
For the selected values of grade of concrete and slab
thickness, the percentage of steel pt is found out using Mu/bd2
ratio and later the required steel is calculated. The spacing of
bars is found from table 37, page 74 of SP 16. This spacing is
checked for IS: 456-2000 requirements.
5. Check for Shear:
Usually shear check is not a concern in slabs due to its
large width, but it is checked as per the requirements specified
in pages 72 and 73 of IS: 456-2000.