Performance Behavior of Confined Brick Masonry Buildings under Seismic Demand

Abstract

Seismic behavior of typical confined brick masonry buildings has been studied. Single and double story reduced scale confined brick masonry building models, representing typical single and double story residential houses in northern Pakistan, have been tested on simple earthquake simulator. The models have been built at 1:4 reduced scale, following the laws of complete model similitude and tested by subjecting them to a sequence of excitations. The models were confined according to the requirements of Eurocode 8. The research work was divided into three distinct phases: testing of prototype masonry materials and assemblages; simulation of reduced scale masonry materials and assemblage; and shaking table test of reduced scale models. Prototype masonry materials and assemblage were tested in compression, diagonal compression and cyclic test. Typical shear failure was observed to be predominant failure mode in both single and double story models. Although, the walls of single story severely damaged, the confining element was able to prevent them from disintegration. Damage was concentrated at the ground floor in the case of double story model. In-plane walls of ground floor were severely damaged during strong shaking. Horizontal bed joint reinforcement is recommended to connect the tie columns and ground floor masonry walls that will improve the seismic behavior of the ground floor walls. Response modification factor of 3.0 and 2.41 was determined for single and double story models respectively, what is in good correlation with Eurcode spectral amplification factors. The model test results indicate that prototype single and double story buildings of the tested type will resist, with moderate damage an earthquake with peak ground acceleration of 0.4 g and 0.25 g, respectively. The same buildings would resist collapse when subjected to earthquakes up to 1.0 g.