A survey on axial load ratios of structural walls in medium-rise residential buildings in Hong Kong

Abstract

It is well recognised by earthquake engineers that there is a strong correlation between the seismic performance of vertical supports (columns and walls) in reinforced concrete (RC) buildings and the axial load acting on them. However, review of the literature has revealed that axial load ratios (ALRs) of a value lower than 0.2 were often assumed in theoretical and experimental studies. Following the common local engineering practices, the present study shows that wall elements that are commonly part of the lateral load resisting system in buildings can have an ALR as high as 0.4 or more, especially when the push-and-pull effects due to lateral loads (seismic or wind) are considered. This paper focuses on the determination of the ALR of the medium-rise structural wall buildings in Hong Kong, one of the most commonly used structural forms of residential buildings in the territory. Based on the findings of the building survey conducted, simplified formulae were proposed to estimate the ALR that is appropriate for expeditious seismic assessments in Hong Kong.