Civil Insight: A Technical Magazine Volume 2 | Page 14
14
TEACHERS’ SECTION
CIVIL INSIGHT 2018
MATERIALS AND METHODOLOGY
Material and Geometrical properties
For the analysis, steel grade of 415 MPa (Mega Pascal) and concrete of 25 MPa having Poisson’s ratio of 0.2 for
both concrete and masonry is used. Beam of 550 mm depth and 300mm width and column of 450mm both
width and depth is used whereas the size of the slab is 150mm. Specifi c weight of RCC and masonry used is
25 and 20kN/m 3 .
Table 1: Material and Geometric properties used in modelling
Parameters
Strength of Concrete (f ck
Modulus of Concrete ( E c
Infill wall thickness (t)
Data
Infill wall height (h), Length (L)
Area of the infill (A p )
Strength of the infill wall (f m )
Modulus of masonry wall (E m )
Strut angle with horizontal (ș)
Infill diagonal length (d inf )
Height of the Column (h c )
Opening reduction factor ( R f )
Equivalent Coefficient ( Ȝ 1 )
Equivalent Strut width (w)
Final Strut width (w')
25000
230
h=2950,
L=4550
13422500
9.6536
5309.4
32.95
5422.6
3500
0.574
0.001025
569.1787
326.7
Unit
M pa
M pa
mm
Remarks
E c =5000ඥ݂ (IS 456:2000)
mm, mm
mm 2
M pa
M pa
Degrees
mm
mm
IS 1893:2002 ( 6th Revision)
(FEMA 356:2000), E m =550f m
30% Opening is considered
mm
mm
w'=R f w
Software modelling and analysis
(ETABS 2000 V.16) programme is used for the fi nite 3D modelling and analysis of the building system. Beam
and column are modelled as frame element while slab is modelled as shell element. Equivalent single diagonal
masonry strut is modelled as pin jointed frame element. Time history linear dynamic analysis was done with
Gorkha-2015 earthquake as ground motion. The time history data is scaled in time domain by response
spectral matching with target spectrum of (IS 1893:2002) specifi ed design response spectrum for seismic
zone-V, with zone factor of Z= 0.36.
Live load of 4kN/m 2 is assigned for the entire fl oor except mass irregular fl oor while higher live load is assigned
for the irregular one to make it irregular and live load of 1.5 kN/m 2 is used for roof plan. Soil type is taken
medium, importance factor taken is 1 and building analysed are considered to be special moment resisting
frame (SMRF) having response reduction factor (R) 5, damping ratio of 5% and fi nally modal analysis with
Eigen Vector and linear time history analysis is done. Only external wall is considered in the analysis with
30% of central opening contained by it.Infi ll is modelled as single equivalent masonry strut recommended by
(FEMA 356:2000).
Width of masonry is calculated by equation (1).
ݓ ൌ ͲǤͳͷ ݀ ሺ݄ ߣ ଵ ሻ ିǤସ (1)
ܧ ݐ ߠʹ݊݅ݏ Ǥଶହ
ߣ ଵ ൌ ሾ
ሿ
Ͷܧ ܫ ݄ (2)