Limiting Drift to Mitigate Pounding Effects on RC Buildings Under Earthquake Shaking

Buildings collide laterally without a sufficient separation gap and cause pounding. It induces massive force or deformation demand at specific storeys or entire buildings and causes damage or sometimes collapses. Usually, code provisions provide an upper limit for the separation gap between buildings or from boundary lines to contain their adverse effects. The separation gap ( S g ) may be limited to a specified per cent of height (e.g. Building Code Provisions (BCP) of Australia, Iran, Peru, and so on) or inelastic displacement obtained by modifying the displacement obtained from elastic analysis using a response reduction factor or displacement amplification factor (e.g. BCP of ASCE 7–16, Canada, Eurocode, India, Iran, Peru, and so on) or a constant value (e.g. BCP of Egypt and Peru). A spectrum of 2D building configurations is considered by varying the number of storeys (3, 5, and 10) and response reduction factors ( R = 3 and 5). The buildings were analysed, designed, and detailed as per IS 456, IS 1893-1, and IS 13920. The inelastic behaviour of these buildings is studied using nonlinear static (NLPoA) and nonlinear time history analysis (NLTHA) using Perform 3D. The performance point and maximum displacement are estimated from the maximum considered earthquake (MCE) and compared with the S g provided in various building code provisions. S g provided in building code provisions apply to only a few combinations of medium-rise buildings (e.g. 3- and 5-storey buildings) and are not applicable to other combinations of short-, medium-, or high-rise buildings (e.g. 3, 5, and 10 storeys). The results are numerically validated with two 3D buildings having 3 and 5 storeys modelled ( R = 5) with and without equivalent struts to account for the infill wall effects. The level of damage increases without including diagonal struts; it may worsen when the buildings pound against each other. Thus, the S g provided in building code provisions may not contain the adverse effects of pounding. Code provisions must consider revising the provisions for pounding in buildings, considering (i) S g between buildings and (ii) the upper limit of S g based on drift limits. Revised recommendations are proposed for the building code provisions.