Development of construction guidelines to prevent out of plane failure of infill wall from seismic load

Abstract

The Mw 6.1 Mae Lao earthquake in 2014 caused unprecedented structural damage in modern Thai history. In general, unreinforced masonry infill walls have been widely used in Thailand, and considerable observed damages were found due to failures of these nonstructural parts. This is due to the fact that unreinforced masonry infill walls have never been considered in a design standard to withstand seismic loads. Therefore, the failures of unreinforced masonry infill walls are likely to be sudden and life-threatening. For this reason, this paper presents an experimental results regarding the effectiveness of existing strengthened and unreinforced masonry infill walls with cement plaster to resist out-of-plane loads. Eight half-scale brick masonry wall panels with reinforced concrete infill frame were constructed and tested by a uniformly distributed lateral load (out-of-plane static tests) following the ASTM Standard E-72 standard (airbag). The results were compared in terms of the flexural loads, out-of-plane deformations, and failure mechanism. Experimental results show that the out-of-plane seismic load capacity of strengthened walls with cellular lightweight concrete, concrete block, and clay brick has more out-of-plane seismic load capacity (about 2.3, 6.0, and >15. times, respectively). In term of failure mechanism, unreinforced masonry wall and masonry wall with cement plaster have the same brittle failure mechanism.