Seismic Analysis of Confined Masonry Shear Walls Using the Wide Column Model
Confined Masonry (CM) structural system consists of masonry walls enclosed by reinforced concrete (RC) confining elements (tie columns and tie beams) and is usually supported by reinforced concrete floors and roof. This technology has been widely used for construction of low and medium rise buildings in Latin America, Europe, South Asia, and Middle East, and it has a proven record of good performance in damaging earthquakes. CM construction is not currently practiced in India and is not addressed by Indian design codes. Seismic analysis of CM wall panels can be performed using Wide Column Model (WCM) also known as Equivalent Frame Model. WCM is a macro model where a wall structure and the supporting floors and roof are idealized as a bare frame. CM walls can be modelled as wide columns with transformed section properties accounting for composite action of masonry and RC tie columns. Beams in these bare frames have rigid segments simulating the effect of wall stiffness, and flexible segments that simulate the effect of floor and roof slabs. WCM has been recognized as a viable model for seismic analysis of CM buildings in Latin American countries, however this model is not well known in India. The results presented in this paper are based on linear elastic analyses of typical multi storey CM solid walls and walls with openings. The output parameters include shear forces, bending moments, stiffness, and lateral displacements. A comparison of the results obtained using the WCM and the Finite Element Method (FEM) has been presented. WCM can be useful for seismic analysis of CM buildings since it does not require significant computational effort and can be applied using a variety of software packages.