Equivalent truss model for the in-plane nonlinear analysis of confined masonry

The confined masonry structure consists of loadbearing walls confined with nominally reinforced concrete elements at perimeter and key locations. The satisfactory performance of confined masonry structures in past earthquakes has evolved this system. In India, RC frames with masonry infill structures are used for seismic resistant construction. RC frame with infill is expected to fail in flexure but improper design and construction lead to the shear failure of RC frames which is essentially same as confined masonry system. In this study, different failure mechanism of RC frame with masonry infill has been studied to investigate the similarities in the seismic behaviour of RC frame and confined masonry. Further, an analytical model for the non-linear static analysis of shear dominant confined masonry walls was proposed and calibrated using experimental studies. The proposed equivalent truss model predicted the expected values of shear strength and displacement for the experimental results. In addition, the effect of aspect ratio and axial stress on the seismic behaviour of confined masonry is studied. A case study is presented illustrating the application of the proposed model for the non-linear analysis of confined masonry buildings.