Earthquake shear in a symmetrical loadbearing masonry building -A dynamic time history analysis

摘要

Loadbearing masonry buildings (LMB) in Australia usually include slip joints, placed on interfaces between concrete slabs and masonry walls to allow for long term differential movements. Since the slip joints have a limited shear capacity, the distribution of the lateral load in this building system is influenced not only by the arrangement and stiffness of the shear walls, but also the shear transfer capacities of the slip joints. Masonry and slip joints have been extensively studied, and reliable knowledge about their behaviour and modelling has been reported. However, very little research has been carried out on the system behaviour under lateral load of LMB incorporating slip joints. Current procedures used in the determination of the lateral load distribution in the shear walls are based on linear elastic analysis and ignore the influence of slip joints. This may lead to inaccurate results due to the load redistribution that occurs once some joints slip. This paper investigates this effect using dynamic numerical simulation to study the performance of a symmetrical building subjected to an earthquake ground motion. The simulation was carried out using a model based on the finite element method which considers both the 3D nonlinear behaviour of the masonry and the slip joints. The analysis endorses previous findings, which indicated that slip in the joints causes a significant redistribution of shear loading in LMB. Linear elastic analysis, if used in the determination of the lateral load distribution, may produce unrealistic results.