Simplified Seismic Out-of-Plane Demand and Capacity Assessment for Mortar-Jointed Bricks Masonry Infills in Seismic Regions of Pakistan

Abstract

In this paper, a practical, district-scale framework to estimate the seismic out of plane (OOP) demand of mortar-jointed brick infills in Pakistan is developed and the demand versus experimental validated capacity is compared. The expression of ASCE 7-16/7-22 OOP is reduced algebraically to an expression with only one coefficient of the district, α_district, such that OOP force is computed by simply multiplying α_district and W_P. Based on the S_DS maps of Pakistan in classes A-E, the calculation of α_district is presented in this paper to all administrative districts of Pakistan except those soil classes that need site-specific analysis according to BCP 2021. When parametric analysis is performed, the ASCE height amplification term converges after 8 storeys (f ≈1.4 - 1.5 for I_p =1.0; f ≈1.7 - 1.8 for I_p =1.5), justifying an envelope constant for national level rapid screening of infill walls enclosed by RC frame, and it is reasonable to take the constant f-factor for all infills especially for infills after 7^th storey. Quasi-static experiment of representative Pakistani infills made of mortar-jointed bricks infill under out-of-plane (OOP) loading were carried out. It was concluded that the Ricci et al. capacity model compared (capacity ratios 0.98) and was used to map capacity against the OOP demand for each district of Pakistan. Comparisons between demands and capacities indicate that in most districts 9-in panels are not safe in high-seismic regions and on weak soils for essential facilities (Ip=1.5). The α_district dataset allows high speed screening (Rapid Screening), district-scale vulnerability mapping, and similar insertion of OOP checks into code amendments and standard design practice by practitioners.