SHAKING TABLE TESTING OF AS-BUILT AND RETROFITTED CLAY BRICK URM CAVITY-WALLS

Engineering Structures, 125

REFERENCE

Giaretton M., Dizhur D., Ingham J. (2016). Shaking table testing of as-built and retrofitted clay brick URM cavity-walls. In Engineering Structures, 125, 70–79 . DOI: 10.1016/j.engstruct.2016.06.032

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.

FINDINGS

• 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.