Civil Insight: A Technical Magazine Volume 2 | Page 15
CIVIL INSIGHT 2018
TEACHERS’ SECTION
15
Where E m , E c , I c are modulus of masonry, concrete and moment of inertia of column respectively. d inf , t inf , h inf
and h c are diagonal length of infi ll, thickness of infi ll, height of infi ll and height of column respectively; angle
of strut with horizontal is ș and w is the strut width.
Wall opening is considered using reduction factor recommended by (Al-Chaar, 2002)
ܣ
ܣ
ܴ ൌ ͲǤሾ ሿ ଶ ͳǤ ቈ ͳ
ܣ
ܣ
(3)
Where R f , A o and A p are reduction factor, open area and infi ll panel area respectively.
Masonry infi ll mechanical properties are calculated as per (IS 1893:2000), 6th revision, that is the compressive
strength of masonry prism can be given as
݂ ൌ ͲǤͶ͵͵݂ Ǥସ ݂ Ǥଷ
(4)
where f b and f mo are compressive strength of brick and mortar in MPa. From (IS 1077-1992), compressive
strength of common burnt clay brick with grade 35 is 35 MPa and as per (IS 1905-1987), minimum strength
of mortar at 28 days with grade of H1 is 10 MPa. Equation (4) gives the masonry strength and modulus of
masonry is then calculated as E m =550f m , that yields 5309.4 MPa.
Model description
In this study, magnitude of mass irregularity considered are 200% and 300% with respect to adjacent story.
Each building model is considered to have 3 bays of 5m length in both X and Y directions and height of 3.5m
in each story totalling 6 stories.
Figure 1: ETAB plan and 3D model of 6-story building
Figure 2: Elevations showing location of mass irregularity with magnitude of 2M
and 3M, where M is story mass of regular fl oor