SHAKING TABLE TESTING OF AS-BUILT AND RETROFITTED CLAY BRICK URM CAVITY-WALLS
Engineering Structures, 125
Scope and methodology
Masonry cavity-wall construction incorporates a continuous air gap that separates the inner and outer brick leaves of the wall cross-section and were developed for the improved thermal performance and reduced moisture transmission. However, they exhibit poor seismic performance due to inadequate connections between the separate masonry leaves.
Fulle scale shaking table testing of five walls closely mimicking in-situ conditions was undertaken to evaluate possible retrofit solutions for clay brick URM cavity-walls.
Two different retrofit solutions were tested: the addition of mechanical screw-ties with different spacings or a combination of mechanical screw-ties and timber strong-backs.
As-built walls. Bending of the original cavity-ties and subsequent differential movements between masonry leaves was observed, with large displacements at relatively small acceleration. The top quarter of the wall collapsed.
Retrofitted walls with screw-ties. Composite rigid-body behaviour of the two wall leaves was obtained. Seismic performance increase decreasing the screw-ties spacing or reducing the screw-ties diameter. Values 30% to 70% higher than the as-built walls were achieved.
Retrofitted walls using screw-ties and timber strong-backs. The seismic capacity increased by three times when compared to the as-built condition and by two times when compared to the wall retrofitted with only mechanical screw-ties.