Appendix

A

Effective width of Equivalent Diagonal Strut:

Masonry infilled reinforced concrete frames constitute a structural system often used in many

countries with relatively high seismic intensity. The seismic vulnerability of these structures

has been demonstrated by the unexpected damages caused by earthquakes. Therefore,

neglecting masonry infills in the design procedure is not a realistic approach.

i. Where

ii. Em and Ef = Elastic modulus of the masonry wall and frame material, respectively

iii. t,h,L = Thickness, height and length of the infill wall, respectively

iv. Ic, Ib = Moment of inertia of the column and the beam f the frame, respectively

v. = tan-1(h/L)

Appendix

B

Linear Static Analysis

In this method, mass of the structure multiplied by design seismic coefficient, acts statically

in a horizontal direction. It is also assumed here that the magnitude of the coefficient is

uniform for the entire members of the structure. Design shears at different levels in a building

shall be computed from the assumption of linear distribution of horizontal acceleration,

varying from zero at the base of the structure to a maximum at the top. For important and

complicated structures this method is not adequate.

Step-1: Seismic Weight:

To calculate the seismic weight of the building ie., the sum of the seismic weights of all the

floors.

W=dead load + amount of imposed load.

Step-2: Fundamental time period:-

vi. The approximate fundamental natural period of vibration(Ta) in seconds of a moment-

resisting frame building without brick infill panels may be estimated by the

expression:

vii. The approximate fundamental natural period of vibration (Ta) in seconds, of all other

buildings may be estimated by the expression:

√

where

h=total height of the building in meters.

d=maximum base dimension of building in meters in a direction parallel to the

applied seismic force.

Step-3: Design spectrum:-

The design horizontal seismic coefficient is determined by following expression:

(4.3)

Provided that for any structure with T<=0.1s, the value of Ah will not be taken less

than Z/2 whatever be the value of I/R

where

Z = zone factor given in Table 4.1

I = importance factor given in Table 4.2

R = response reduction factor given in Table 4.3

Sa/g= average response acceleration coefficient for rock or soil sites

Fig.4.1.shows the proposed 5% spectra for rocky and soil sites

For rocky, or hard soil sites.

Sa/g= {1+15*T 0.00<=T<=0.10

2.50 0.10<=T<=0.40

1.00/T 0.40<=T<=4.00

For medium soil sites.

Sa/g= {1+15*T 0.00<=T<=0.10

2.50 0.10<=T<=0.55

1.36/T 0.55<=T<=4.00

For soft soil sites.

Sa/g= {1+15*T 0.00<=T<=0.10

2.50 0.10<=T<=0.6

1.67/T 0.67<=T<=4.00

Response Spectra for Rock and Soil sites for 5% Damping

Table-4.1 Zone factor, Z:

Seismic zone II III IV V

Seismic

intensity

Low

Moderate

Severe

Very severe

Z 0.10 0.16 0.24 0.36

Table-4.2 Importance factor, I:

Structure Value of I

Important community structure

Others

1.5

1.0

Table-4.3 Response reduction factor for building systems:

Lateral load resisting system Value of R

Building frame system.

1. Ordinary R.C. moment resisting frame

(OMRF).

2. Special R.C. moment resisting frame

(SMRF).

3. Steel frame with

i. Concentric braces

ii. Eccentric braces.

3.0

5.0

Table-4.4 Multiplying factors for obtaining values for other damping:

Damping

percent

0 2 5 7 10 15 20 25 30

Factors 3.20 1.40 1.00 0.90 0.80 0.70 0.60 0.55 0.50

Step-4: 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:

where

Ah=design horizontal acceleration spectrum (step-3).

W=seismic weight of the building (step-1).

Step-5: Distribution of design force:-

The design base shear (VB) calculated in step-4, shall be distributed along the

height of the building as per the following expression:

∑

where

Qi=lateral force at the floor i.

VB=Base shear.

Wi=seismic weight of floor i.

hi =height measured from the base of the building to the roof or any floor i.

n =number of storeys in the building.

Step-6: Distribution of shear:-

∑

where

Vj=shear in jth

storey

Appendix

C

Response Spectrum Method by using Staad Pro

This is accurate method of analysis. The design lateral force at each floor in each mode is

computed by STAAD Pro in accordance with IS: 1893 (Part 1)-2002. The software provides

result for design values, modal masses and storey wise base shear.

Methodology: The design lateral shear force at each floor in each mode is computed by

STAAD in accordance with the IS: 1893 (Part 1) -2002 following equation.

Qik = Ak*fik*Pk*Wk and Vik = Qik

STAAD utilizes the following procedure to generate the lateral seismic loads.

[1] User provides the value for (Z/2)x(I/R) as factors for input spectrum.

[2] Program calculates time periods for first six modes or as specified by the user.

[3] Program calculates Sa/g for each mode utilizing time period and damping for each mode.

[4] The program calculates design horizontal acceleration spectrum Ak for different modes.

[5] The program then calculates mode participation factor for different modes.

[6] The peak lateral seismic force at each floor in each mode is calculated.

[7] All response quantities for each mode are calculated.

[8] The peak response quantities are then combined as per method (CQC or SRSS or ABS or

TEN or CSM) as defined by the user to get the final results.