STRUCTURAL ANALYSIS AND DESIGN REPORT

OF
RESIDENTIAL BUILDING

Owner’s Name: Mr. Ramlal Subedi

December, 2022

Designed By: Er. Yadav Nepal (NEC Regd. No: 7788 Civil ‘A’)
DHOD of Civil Department/ Lecturer
Lumbini Engineering Management and Science College
Rupandehi
 Structural Analysis and Design Report

TO WHOM IT MAY CONCERN

This report comprises the summary of the structural design of Residential Building. The report
consists of design procedures adopted, assumptions made, and the input assign in the design. During design
it is assumed that the client will completely followed the architectural as well as the structural design. It is
also assumed that the construction will be supervised by a professional engineer.
The designer will not be responsible if any alteration or change to the structural system is made
by the client or contractor without the prior permission from the designer, or the alteration to the non-
structural system is made such that the weight of each individual floor or the weight of the whole building
is altered by more than 10% of the design weight of the floor and the total weight.
The design calculations and derivations are limited to only to let the concerned people know the
methodology adopted. However, the calculation may be provided to the client or the concerned authorities
when needed, upon request.

………………………….
Er. Yadav Nepal
Designer

Residential Building
 Structural Analysis and Design Report

CONTENTS

Notations:
1. Name of Building
2. Structural Feature
2.1 Foundation
2.2 Framing Descriptions
3. Codes and Standards
4. Materials (characteristics)
5. Soil Bearing Capacity
6. Loads
6.1 Dead Load
6.2 Live Load
6.3 Earthquake Load
7. Load Combinations
8. Structural Analysis
8.1 Method (type, name and version of programme)
8.2 Conditions
9. Input Data
10. Output (summary/extract-stresses, bending moment, displacement, support reaction)
11. Member Design
11.1 Slab
11.2 Beam
11.3 Column
11.4 Foundation
11.5 Secondary Elements
11.5.1 Staircase
12. Design Data

Residential Building
 Structural Analysis and Design Report

Appendix:
I) Abbreviations:

NOTATIONS:

SYMBOLS DESCRIPTION

Ac : Area of concrete
Ag : Gross area of section
Ast : Area of tensile steel
Asc : Area of compression steel
Asv : Area of vertical stirrups
b : Width of beam or shortest dimension of column
D : Overall depth of a beam or slab
d : Effective depth of a beam or slab
emin : Minimum eccentricity
fck : Characteristic compressive strength of concrete
fsc : Compressive stress in steel corresponding to a strain 0.002
fst : Tensile stress in reinforcement
fy : Characteristic yield strength of steel
Ld : Development length of bar
L : Length of column or span of beam
Lo : Anchorage length of bar
Leff : Effective length of beam or column
Mu : Factored design moment
Mu,lim : Limiting moment of resistance
Mux : Factored design moment along x-x Axis
Muy : Factored design moment along y-y Axis
Mux,l : Maximum uniaxial moment capacity with axial load, bending about x-x
axis
Muy,l : Maximum uniaxial moment capacity with axial load, bending about y-y
axis
I : Moment of inertia of a section
Ix,Iy : Moment of inertia about X and Y axis
P : Axial load
Residential Building
 Structural Analysis and Design Report

Pu : Factored design axial load

pt : Percentage of tension reinforcement
Sv : Spacing or vertical stirrups
V : Shear force
Vu : Factored shear force
Vus : Design strength of shear reinforcement
τc : Shear stress in concrete
τv : Nominal shear stress
τbd : Design bond stress
τc, max : Maximum shear stress in concrete with shear reinforcement
Ф : Diameter of bar
A st,req : Required area of tensile steel
A sc,req : Required area of compression steel
A st,prov : Provided area of tensile steel
A sc,prov : Provided area of compression steel
Sv, prov : Provided spacing of vertical stirrups
W : Total un-factored Load
w : Total Factored Load
Ly : Effective length of slab in longer direction
Lx : Effective length of slab in shorter direction
k : Constant or coefficient or factor
p : Calculated maximum bearing pressure of soil

Residential Building
 1. Project Details

Name of the Project : Structural Analysis and Design of RCC Frame Structure
Type of Building : Residential Building

The building is a three storied building on rigid footing with a flat RC terrace, and a flat roof on top
of staircase portion.

Total Height of the Building : 9.6 m

Lateral Dimension of the Building : 12.19 m X 6.86m
Floor Height : 3.2 m
Total No. of Staircase :1 (Dog-Legged Staircase)

General Information:

 Structural Analysis Software :- ETABS version 16.2.1

 Structural System :- RCC Frame
 Foundation System :- Isolated Strap Footing

2. Structural Feature

2.1 Foundation

Type:All the footings of the building are shallow type footing. Isolated footing has been provided in the structure
and eccentric footing with strap beam has been provided in zero boundary cases.

2.2 Framing Description:

2.2.1Beam
Size:All the beams at foundation and plinth are 9” x 9” and floor level are of size 1’-2” x 0’-9”.

Location/Orientation:All the beams are concentric with the columns i.e. the center line of beams match with
that of column’s center line. It is to be noted that the side surface of beams may be matched with surfaces of
walls/partitions by additional concrete as required in architectural drawings.

2.2.2Column:
Size: Basically the column used in the building is of size1’-0”x1’-0”.

2.2.3 Slab:
Size: Concrete slab 5” thick is provided at the floor level. For staircase cover, thickness of concrete slab is
also5”.

3. Loading on Structural Model

The following considerations are made during the loading on the structural model:
 The loads distributed over the area are imposed on area element and that distributed over length are
imposed on line element whenever possible.
 Where such loading is not applicable, equivalent conversion to different loading distribution is carried
to load the model near the real case as far as possible.
 For lateral load, necessary calculations are performed to comply with the requirements of NBC 105:
2020.

4. Materials (characteristics)
Page 6 of 33
Concrete:
All Concrete Structures (substructure as well as super structure) are designed for concrete of grade
M 20 to IS 456:2000
Reinforcement Bar:
- High strength deformed steel bars: Grade Fe500 to IS 1786.

5. Soil Bearing Capacity

The soil bearing capacity shall not be less than 150 KN/m2 as per design assumption.
6. Loads
6.1 Dead Load:
All loads/forces due to gravity on the components of the building structure including the structures
self-weight, roofing, flooring, suspended ceiling, wall/partition, services including machinery, piping, rack with
all associated finishing permanently attached thereto are calculated in accordance with NBC 105:2020.

6.2 Imposed Load:

The load assumed to be produced by the intended use and occupancy of a building, including the
loads of movable partition, impact, vibration, and dust, but excluding wind, seismic, snow and other loads due
to temperature changes, creep, shrinkage, differential settlement, etc., in accordance with NBC 105:2020.
The earthquake induced lateral loads are determined and used from the spectral load cases based on NBC:
105:2020 Spectrum for Soil Type B. Lateral load thus developed is the product of structural seismic mass,
modal response and respective spectral ordinates.

PARAMETERS TO BE CHECKED AFTER STATIC ANALYSIS OF

STRUCTURE.
Calculation of Horizontal Base Shear Coefficient
Factors and Coefficient,
Sesmic Zonic Factor, z (as per clause 4.1.4) = 0.3

Page 7 of 33
Page 8 of 33
Importance Factor, I (as per clause 4.1.5) = 1
Soil type = B
Height of Building, H= 9.6m
Time Period Calculation
Amplified Time Period, T (sec) =1.25 x 0.075 x H ^(3/4)
= 0.511 sec < 1 sec
Elastic Site Spectra for Horizontal Loading
Spectral Shape Factor Ch(T),

Elastic Site Spectra (Ultimate Limit State), C(T) =Ch(T)ZI

where,
Spectral Shape Factor, Ch(T) =2.5, as per table 4-1
Ch(T) = 2.5 x 0.3 x 1= 0.75
Elastic Site Spectra (Serviceability Limit State), Cs(T) = 0.20Cs(T)
Cs(T) = 0.20Cs(T)= 0.20 x 0.75 = 0.15

Page 9 of 33
Overstrength Factors

HORIZONTAL BASE SHEAR COEFFICIENT

Ultimate Limit State
Cd(T1) = C(T1)/ Ru x ꭥs = 0.75 / 4 x 1.5 = 0.125
Serviceability Limit State
Cd(T1) = Cs(T1)/ ꭥs = 0.15 /1.25 = 0.120

Page 10 of 33
Exponent related to the structural periods, K.

Therefore, value of k = 1.006, for amplified Time period (T) = 0.511 sec. after interpolation.
User Coefficient Auto Seismic Load Calculation
This calculation presents the automatically generated lateral seismic loads for load pattern EQxULS using the user input
coefficients, as calculated by ETABS.

Direction and Eccentricity

Direction = Multiple

Eccentricity Ratio = 10% for all diaphragms

Factors and Coefficients

Equivalent Lateral Forces

Base Shear Coefficient, C C = 0.125

Base Shear, V V = CW
Calculated Base Shear

Period Used W V
Direction C
(sec) (kN) (kN)
X 0 0 2221.2522 277.6565
X + Ecc. Y 0 0 2221.2522 277.6565
X - Ecc. Y 0 0 2221.2522 277.6565

Applied Story Forces

Page 11 of 33
 Story Elevation X-Dir Y-Dir
m kN kN
Story3 9.6 118.3011 0
Story2 6.4 106.3841 0
Story1 3.2 52.9713 0
Base 0 0 0

User Coefficient Auto Seismic Load Calculation

This calculation presents the automatically generated lateral seismic loads for load pattern EQyULS using the
user input coefficients, as calculated by ETABS.

Direction and Eccentricity

Direction = Multiple

Eccentricity Ratio = 10% for all diaphragms

Factors and Coefficients

Equivalent Lateral Forces

Page 12 of 33
Base Shear Coefficient, C C = 0.125
Base Shear, V V = CW

Calculated Base Shear

Period
W V
Direction Used C
(kN) (kN)
(sec)
Y 0 0 2221.2522 277.6565

Y + Ecc. X 0 0 2221.2522 277.6565

Y - Ecc. X 0 0 2221.2522 277.6565

Applied Story Forces

Page 13 of 33
User Coefficient Auto Seismic Load Calculation

This calculation presents the automatically generated lateral seismic loads for load pattern EQxSLS using

the user input coefficients, as calculated by ETABS.

Direction and Eccentricity

Direction = Multiple

Eccentricity Ratio = 10% for all diaphragms

Factors and Coefficients

Equivalent Lateral Forces

Base Shear Coefficient, C C = 0.12

Base Shear, V V = CW

Calculated Base Shear

Period Used W V
Direction C
(sec) (kN) (kN)

X 0 0 2221.2522 266.5503

X + Ecc. Y 0 0 2221.2522 266.5503

X - Ecc. Y 0 0 2221.2522 266.5503

Applied Story Forces

Residential Building
User Coefficient Auto Seismic Load Calculation

This calculation presents the automatically generated lateral seismic loads for load pattern EQySLS using the user input coefficients, as

calculated by ETABS.

Direction and Eccentricity

Direction = Multiple

Eccentricity Ratio = 10% for all diaphragms

Factors and Coefficients

Equivalent Lateral Forces

Base Shear Coefficient, C C = 0.125

Base Shear, V V = CW

Residential Building
Calculated Base Shear

Period
W V
Direction Used C
(kN) (kN)
(sec)

Y 0 0 2221.2522 266.5503

Y + Ecc. X 0 0 2221.2522 266.5503

Y - Ecc. X 0 0 2221.2522 266.5503

Applied Story Forces

Residential Building
 Maximum Story Displacement (EQxULS)

Maximum Story Displacement (EQyULS)

Permissible Actual maximum

maximum story story displacement

displacement(mm) (mm)

60 > 18.25

Safe OK

Maximum Story displacement are within 60 mm permissible value.

Residential Building
 Maximum Story Displacement (EQxSLS)

Maximum Story Displacement (EQySLS)

Permissible Actual maximum

maximum story story displacement

displacement(mm) (mm)

57.6 > 17.52

Safe OK

Maximum Story displacement are within 57.6 mm permissible value.

Residential Building
 Maximum Story Drifts (EQxULS)

Maximum Story Drifts (EQyULS)

Permissible Drift Actual Drift Ratio

Ratio for Ultimate

Limit State

0.00625 > 0.002299

Safe OK

All are within 0.00625 permissible Drift Ratio

Residential Building
 Maximum Story Drifts (EQxSLS)

Maximum Story Drifts (EQySLS)

Permissible Drift Actual Drift Ratio

Ratio for

Serviceability Limit

State

0.006 > 0.002207

Safe OK

All are within 0.006 permissible Drift Ratio

Residential Building
Modal analysis was performed in order to determine the vibration modes of a building. The first and second

modes of the building are translation in X and Y directions while the third mode is in torsion. More than

90 % of mass has been participated in twenty-five mode in both directions. The natural periods and modal

participating mass ratios are shown in table above.

Permissible Ratio Actual Ratio

1.5 > 1.135

Safe OK

Thus Structure is Safe In Torsion In Both Direction

Residential Building
7. Load Combination (For Parallel System)

The load combinations are based on NBC:105: 2020. The following load combinations are specified

by NBC: 105: 2020.

Static Load Combination:

1.5 Dead Loads + 1.5 Live Loads
Seismic Load Combination
1.2 Dead Loads+ 1.5 Live Loads
Dead Loads + Y Live Loads ± Earthquake Loads
where, Y= 0.6 for storage
Y= 0.3 for other use

For seismic loading, mass equivalent to the load that is composed of 100% of Dead Load and
30% of Live Load is taken into consideration.

8. Structural Analysis:
8.1 Method:
Type: All the Structural elements of reinforced concrete are designed to Limit State Theory.
Program Used: ETABS version 2016.2.1 is used for the analysis and design of three-dimensional structures,
in which the spatial distribution of the mass and stiffness of the structure is adequate for the calculation of
the significant features of structures.
8.2 Conditions:
Since, all the columns are rigidly connected to the foundation; we can assume that there would
be no any deflection or rotation of these columns at the base. Hence, the supporting conditions for column
are fixed.
Similarly, at the level where the RC slab panels are rigidly connected to the beams, we assume
that there would be equal displacement i.e. the concrete floor acts as a rigid floor diaphragm.
9. Input Data
Generally, the design of structure in ETABS starts with the modeling of structure and then
defining all the parameters required for the analysis and design (such as materials, conditions as mentioned
above, loading information, codes and standards, etc.)
The input data for the design of structure generally includes the dead load (except the self-weight
of structure presented in the model), the imposed load, the lateral loads, the wind load and other special
loads (for example, loads due to thermal effects)

Residential Building
The 3D model of building is as shown below:

9.1 Dead and Imposed Load:

Wall Load Schedule

Load/ m Load/ m

Material w/o opening with opening

Kn/m Kn/m

Exterior wall 12.5 8.8

Interior wall 6.3 5.6
Parapet Wall 2 2

Floor Finish Schedule

Load of 1.25 Kn/m2 is applied on all slabs.

Residential Building
Figure depicting Floor Finish, Live Load, Wall Load, Staircase Load and Earthquake Load
Figure depicting Floor Finish Load

First Floor Second Floor

Top Floor

Residential Building
Figure depicting Live Load

First Floor Second Floor

Top Floor

Residential Building
Figure depicting Wall Load

Residential Building
9.3 Lateral Loads:
ETABS automatically incorporates all the required calculations for lateral loads based on the
input data we provide. The required parameters for lateral load calculation have already been mentioned
above in 6.3.
Based on seismic coefficient method, ETABS utilizes the following procedure to generate the lateral
seismic loads.
User provides seismic zone co-efficient and desired seismic load command mentioned in 6.3 and ETABS
automatically calculates the base shear and distributed the lateral force in each storey.

10. Output:
After all the loading information is provided in the structural model, ETABS analyses the
structure and gives the required output (i.e. exact stress, support reactions, displacement, bending moment,
shear force, etc.)
Some of the output information as obtained from ETABS after analyzing the structure is shown as below.

Fig. Bending Moment Diagram of beams and columns for moment 2-2 and moment 3-3

Residential Building
Figure depicting the results of exact stresses (Bending moment, Shear force, deflections, etc.)
induced in a sample beam.

Fig. Axial Diagram of columns

Residential Building
Table depicting the support reactions - Load Case: 1.5(DL+LL)

The Reactions in the column base for the foundation combination is as given below:

From above result, it was found that the critical isolated footing is at joint 4 i.e. F3

Residential Building
 Figure depicting Beam Column Detail of Grid 1-1&2-2

Residential Building
 Figure depicting Beam Column Detail of Grid 3-3 & A-A

Residential Building
 Figure depicting Beam Column Detail of Grid B-B & C-C

Residential Building
Figure depicting Beam Column Detail of Grid D-D

Residential Building
 Structural Analysis and Design Report of Residential Building

Design of Slab
Design Data
fck = 20 N/mm2
fy = 500 N/mm2
n
Dimensions of the slab (c/c distance bet supports),
Length of short span, lx = 3.353 m
Length of long span, ly = 4.039 m
Width of the supporting beam, = 230 mm
Clear cover to main reinforcement = 15 mm
Assume dia. of reinforcement steel = 8 mm
Calculations
Assume the thickness of slab as 127 mm ;
Effective depth, deff = 108 mm
Effective span, lx = 3.3528 m (or) 3.231 m whichever is less; = 3.231 m
ly = 4.0386 m (or) 3.917 m whichever is less; = 3.917 m
(ly / lx ) = 1.21 < 2 ; Here, (ly / lx ) is less than 2
Hence design the slab as two way slab

Load Calculations
2
Dead Load of slab = 0.127 x 25 = 3.18 KN/m
2
Finishing load plus on slab = 1.25 KN/m
2
Total Dead load acting on the slab = 4.43 KN/m
2
Live Load on slab = 2.0 KN/m
2
Factored Design Load, W = 9.65 KN/m

Support Condition (Type of panel according to support condition)

One Long Edge Discontinuous For this support condition,
Short span coefficient for (ly / lx ) = 1.21, Long span coefficient,
For negative moment, ax = 0.0525 For negative moment, ay = 0.037
For positive moment, ax = 0.0395 For positive moment, ay = 0.028
Moment Calculation
2 2
Max. BM per unit width, Mx = ax w l x & My = ay w l x
2
Mu Mu / bd Ast, req
Pt %
KNm N/mm2 mm2
For Short Span,
At mid span, 3.98 0.34 0.08 86
At supports, 5.29 0.45 0.11 115
For Long span,
At mid span, 2.82 0.28 0.07 71
At supports, 3.73 0.37 0.09 94
 Structural Analysis and Design Report of Residential Building

Ast , min = (0.12/100) bD = 2

152 mm
Reinforcement details
Provide 8 @ 150 mm c/c at midspan & supports for short span
(Ast pro. = 335 mm2 )
Provide 8 @ 150 mm c/c at midspan & supports for long span
(Ast pro. = 335 mm2 )

Check for Deflection

Percentage of tension reinforcement = 0.26 %
fs = 0.58 fy (Ast req / Ast pro) = 74
Refer Fig. 4 of IS 456,
Modification factor = 2
( l/ d) max = ( l/ d) basic x kt x kc = 46
( l/ d)provided = 30
< ( l/ d) max (i.e. = 46) OK
Hence safe in deflection.

Check for shear

Shear force per m strip (W*lx/2), V = 15.59 KN/m
Shear stress , (V/bd), τv = 0.120 N/mm
2

Pt = 0.26 %
Design Shear Strength of Concrete
τc = 0.365 N/mm
2
Refer Table 19, IS 456
> τv (i.e. = 0.12) OK
Since τc > τv, so safe in shear.
 Structural Analysis and Design Report of Commercial cum Residential Building

Sample Design of Isolated Footing

F3 Design of Isolated Footing (Footing 2-B)

Axial Load = 482.87 KN

Add 10% of self wt of footing = 48.29 KN
Total Load on footing = 531.16 KN
Assumed bearing capacity of soil = 150 KN/m²
Grade of concrete = M 20
Grade of steel = Fe 500
Size of Column : b = 305 D = 305 mm
Area of footing = Total Load on footing / bearing capacity
Area of footing = 3.54 m²
App.Side of footing = 1.88 m
Size of footing : lx = 2 ly = 2 m
Provided area of footing = 4.00 m² > 3.54 m²
Hence safe
Bending Moment (Mu)
Net upward pressure intensity = 132.79 KN/m² < 150 KN/m²

NUPI due to factored load = 1.5*Total load/provided area of footing

NUPI due to factored load = 199.18 KN/m²
Mu = 1/2*NUPI*(lx-b)/2*(lx-b)/2 per m
Mu = 71.53253156 KN-m
Effective depth(d) required = sq.rt of Mu / 0.138*fck*ly
d= 113.8366898 mm
Depth from B.M. consideration
Projection beyond the critical section = 0.85 m
Max.bending moment, M = 95377 Nm
Factored moment (Mu) = 1.5 M = 143066 Nm
Equating Mu,lim to Mu
0.133fckbd² = 0.133* 20*305*d²
d= 420 mm
Providing 12mm Ø bars at a clear cover of 50 mm
Effective cover to upper layer of bars = 56 mm
Overall all depth required = 476 mm
So provide overall depth of 500 mm
Adopt over all depth = 500 mm
Actual Effective depth(d) = 444 mm

Area of tension steel is given by Mu = 0.87*fy*Ast(d-fy*Ast/(fck*lx)

By solving the equation Ast = 775 mm²
% of steel=100*Ast/(bd) = 0.17 %
Min. steel as per IS.456-2000 = 0.12%bd = 532.80 mm²
Provide 12 mmØ @ 150mm c/c in both ways
Area of steel provided = 1431.33 mm² > 775 mm² OK
 Structural Analysis and Design Report of Commercial cum Residential Building

Check for shear

a) One way action
The critical section is taken at a distance "d" away from the face of column
Factored Shear force(Vu) = NUPI*(((lx-b)/2)-d)
Vu = 80.371 KN
Nominal Shear stress(Tv) = Vu/bd
Tv = 0.18 N/mm²
Shear strength of M20 concrete with 0.322 % steel
Tc = 0.3946 N/mm² > Tv Hence OK
b) Shear two way action
The critical section is taken at a distance 0.5d away from the face of column
Shear force (Vu) = NUPI(Area of footing-((b+d)*(D+d)))
Vu = 684.9931 KN
Nominal Shear stress(Tv) = Vu/Bod
Perimeter of section(Bo) = 2((b+d)+(D+d))
Bo = 2996 mm
Tv = 0.5149 N/mm²
Shear strength of M20 concrete with T'c = Ks Tc where Ks = (0.5+Bc)
Bc = b/D = 1
Therefore,
Ks = 1 (Since Ks < or =1)

T'c =Tc = 0.25SQRT OF 20 = 1.11 > 0.515 Hence OK

 Design of Footing Using Excel Sheet
Strap Beam Footing

Input Parameter
Factored Load on column
Factored Load on column, C1 P1 = 571.60 KN
Factored Load on column, C2 P2 = 734.30 KN
C/C distance between C1 & C2 l = 3.353 m
Size of Column, C1 = 0.305 m
Size of Column, C2 = 0.305 m
2
Strenth of concrete fck = 20.00 N/mm
2
Strenth of rebar fy = 500.00 N/mm
2
Safe bearing capacity of soil, SBC qc = 150.00 KN/m
Working Load
Column, C1 Pu1 = 381.07 KN
Column, C2 Pu2 = 489.54 KN
Assume weight of footing and backfill as 10% of total weight
Total load on earth = 957.66 KN
2
Footing area required = 6.38 m
Let L1 and L2 be the lengths of footings under column 1 and 2 respectively
and B be the width of footing
Then B(L1+L2) = 6.38
Assuming B = 2.00 m
L1 + L2 = 3.19 m
The distance from the resultant of the column forces to the center of Column C2
X = 1.47 m
Center of gravity of the two footings should coincide with the resultant of the two
column load to ensure uniform soil pressure below the two footings.

BXL1(l+b1/2-L1/2)
X =
B(L1+L2)

2
0.5L1 - 3.91L1 + 4.38 = 0 -----Eq 1

Solving Eq 1 we get
L1 = 1.72
L2 = 1.47

a1 = 0.15 m
b = 3.50 m
Now, X = 2.04 m
Provide L1 = 1.50 m
L2 = 1.50 m
2
Total area provided for footing = 6.00 m
2
Net upward soil pressure = 159.61 KN/m
Cantilever moment Mu1 = 114.64 KN-m
Factored moment = 171.96 KN-m
Depth required for bending Mu = 0.133 X Fck X B X dX d
d = 176.50
provide effective depth d = 250.00
Overall depth of slab, D = 300.00 mm

Checking for shear

Maximum shear force Vu = 83.20 KN
2
Assume 0.2 % of steel Ʈc = 0.32 N/mm
2
Normal shear stress Ʈv= = 0.22 N/mm
Ʈc > Ʈv

Hence OK

Reinforcement in Footing
Area of steel Required
2
Mu1/Bd = 0.96
Table 2 of SP-16 gives steel P t= 0.10
Area of steel Required = 621.60
Increase the percentage of steel
2
Adopt 0.25 % of steel = 1,500.00 mm
Provide bar dia = 12.00
Provided rebar area = 113.11
Spacing required = 150.82
Provide 12mm dia bar @ 150 mm c/c = 1,508.16 >
Hence OK

Design of Strap beam

Maximum shear fore at centre line of C1
V1 = -24.34 KN
V2 = 356.73 KN
Maximum shear fore at centre line of C2
V1 = 119.71 KN
V2 = 369.83 KN
Maximum Factored SF C1 Vu1 = 535.09 KN
Maximum Factored SF C2 Vu2 = 554.74 KN
Point of zero shear force from centre of C1 =
x = 1.65 m
Maximum BM from C1 = -110.93 KN-m
Maximum BM from C2 = -283.78
Factored BM = 425.68 KN-m
2
BM = 0.133fckbd

Assume, Provide width of strap beam, b = 350.00 mm

Depth of beam required = 676.18 mm
Overall depth of beam, dD = 700.00 mm

Solving above equation gives

2
Reinforecement required, Ast = 1,690.14 mm
Provide bar dia = 20.00
2
Provided rebar area = 314.20 mm
No of bar required = 5.38
Provide = 6.00 nos of bars
2
Now area of steel = 1,885.20 mm
%steel = 0.77 %
 Design of Staircase
Basic dimensions of Staircase = L (m) B (m)
4.0386 2.1336
Floor to Floor Height = 3.2 m
Rise = 178 mm
Tread = 254 mm
Secθ = 1.221
Number of risers required = 18.00 Nos
Number of risers required in each flight = 6.00 Nos
Number of treads required per flight = 5.00 Nos
Thickness of wall at landing = 230 mm
Span of staircase L = 4.2686 m
Thickness of Waist Slab D = 150 mm SAFE
Clear cover to reinforcement d' = 15 mm
Diameter of bar ф = 12 mm
Effective depth d = 129 mm
Select Grade of Concrete fck = 20 N/mm²
Select Grade of Steel fy = 500 N/mm²
xu max/d = 0.456
Ru, lim = 2.66

Design of First Flight

One way Single Span, Simply Supported inclined Slab

Load calculation :

Dead load of the slab DLws = 4.58 kN/m²

Weight of Steps DLstps 2.23 kN/m²
Floor finish(Roof finish) FF = 1.25 kN/m²
Live load LL = 2 kN/m²

Total load TL = 10.05 kN/m²

Total Factored load TFL = 15.08 kN/m²

Moment and Area of Steel calculations:

Mu Mumax Ast reqd Pt reqd Min Ast Dia of bar Spacing Ast pro
kN.m KNm mm² % mm² mm mm mm²
34.349 44.26506 710.169 0.55% 180 12 150 753.982 SAFE
SAFE

Check for Deflection

The effective depth provided = 129 mm
fs = 273.15 N/mm²
Pt Provided = 0.58%
Required depth under deflection consideration = 110.87 mm HENCE SAFE

Distribution Steel
Ast reqd Dia of bar Spacing Ast pro
mm² mm mm mm²
180.600 8 150 335.103 SAFE

Check for shear

factored shear touv Pt touc touc'
load KN force KN N/mm² % k N/mm² N/mm²
15.08 32.19 0.2495 0.29% 1.25 0.22 0.275 HENCE SAFE

Design of other Flight is Similar to the design of First Flight.

ETABS 2016 16.2.1 License #*1E7YBEY4KKSBGAP

ETABS 2016 Concrete Frame Design

IS 456:2000 Beam Section Design

Beam Element Details Type: Ductile Frame (Summary)

Unique Length
Level Element Section ID Combo ID Station Loc LLRF
Name (mm)
BEAM 230 X 355 (MM X DL + YLL -
Story1 B3 14 152.5 3962.4 1
MM) EQX

Section Properties
b (mm) h (mm) bf (mm) ds (mm) dct (mm) dcb (mm)
230 355 230 0 25 25

Material Properties
Lt.Wt Factor
Ec (MPa) fck (MPa) fy (MPa) fys (MPa)
(Unitless)
22360.68 20 1 500 500

Design Code Parameters

ɣC ɣS
1.5 1.15

Factored Forces and Moments

Factored Factored Factored Factored
Mu3 Tu Vu2 Pu
kN-m kN-m kN kN
-50.5908 0.4555 51.6249 0.483

Design Moments, Mu3 & Mt

Factored Factored Positive Negative
Moment Mt Moment Moment
kN-m kN-m kN-m kN-m
-50.5908 0.6815 0 -51.2723

Design Moment and Flexural Reinforcement for Moment, M u3 & Tu

Design Design -Moment +Moment Minimum Required
-Moment +Moment Rebar Rebar Rebar Rebar
kN-m kN-m mm² mm² mm² mm²
Top (+2
-51.2723 391 0 391 175
Axis)
Bottom (-2
0 196 0 0 196
Axis)

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ETABS 2016 16.2.1 License #*1E7YBEY4KKSBGAP

Shear Force and Reinforcement for Shear, Vu2 & Tu

Shear Ve Shear Vc Shear Vs Shear Vp Rebar Asv /s
kN kN kN kN mm²/m
59.1017 36.8329 30.36 29.5731 254.94

Torsion Force and Torsion Reinforcement for Torsion, T u & VU2

Tu Vu Core b1 Core d1 Rebar Asvt /s
kN-m kN mm mm mm²/m
0.3526 51.3838 200 325 221.69

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ETABS 2016 16.2.1 License #*1E7YBEY4KKSBGAP

ETABS 2016 Concrete Frame Design

IS 456:2000 Column Section Design

Column Element Details Type: Ductile Frame (Summary)

Unique Length
Level Element Section ID Combo ID Station Loc LLRF
Name (mm)
COL 305 X 305 (MM X DL + YLL -
Story1 C4 4 0 3200 0.628
MM) EQy

Section Properties
Cover (Torsion)
b (mm) h (mm) dc (mm)
(mm)
305 305 56 30

Material Properties
Lt.Wt Factor
Ec (MPa) fck (MPa) fy (MPa) fys (MPa)
(Unitless)
22360.68 20 1 500 500

Design Code Parameters

ɣC ɣS
1.5 1.15

Axial Force and Biaxial Moment Design For Pu , Mu2 , Mu3

Design Pu Design Mu2 Design Mu3 Minimum M2 Minimum M3 Rebar Area Rebar %
kN kN-m kN-m kN-m kN-m mm² %
414.1711 -57.9282 8.2834 8.2834 8.2834 1141 1.23

Axial Force and Biaxial Moment Factors

Initial Additional Minimum
K Factor Length
Moment Moment Moment
Unitless mm
kN-m kN-m kN-m
Major
0.698132 2845 -0.5334 0 8.2834
Bend(M3)
Minor
0.685715 2845 -23.1713 0 8.2834
Bend(M2)

Shear Design for Vu2 , Vu3

Shear Vu Shear Vc Shear Vs Shear Vp Rebar Asv /s
kN kN kN kN mm²/m
Major, Vu2 32.3559 63.8335 30.3776 32.3559 338.07
Minor, Vu3 36.7513 63.8335 30.3776 36.7513 338.07

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ETABS 2016 16.2.1 License #*1E7YBEY4KKSBGAP

Joint Shear Check/Design

Joint Shear Shear Shear Shear Joint Shear
Force VTop Vu,Tot Vc Area Ratio
kN kN kN kN cm² Unitless
Major Shear, Vu2 N/A N/A N/A N/A N/A N/A
Minor Shear, Vu3 N/A N/A N/A N/A N/A N/A

(1.1) Beam/Column Capacity Ratio

Major Ratio Minor Ratio
N/A N/A

Additional Moment Reduction Factor k (IS 39.7.1.1)

Ag Asc Puz Pb Pu k
cm² cm² kN kN kN Unitless
930.3 11.4 1265.2551 311.7594 414.1711 0.892593

Additional Moment (IS 39.7.1)

Ma
Consider Length Section KL/Depth KL/Depth KL/Depth
Moment (kN-
Ma Factor Depth (mm) Ratio Limit Exceeded
m)
Major Bending (M3 ) Yes 0.889 305 6.512 12 No 0
Minor Bending (M2 ) Yes 0.889 305 6.396 12 No 0

Notes:

N/A: Not Applicable

N/C: Not Calculated

N/N: Not Needed

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