Experimental clarification of the lateral performance of squat mud infill walls in the timber frames of traditional Japanese residential houses

Abstract

This paper presents the experimental results of squat mud infill walls with three different height aspect ratios in the timber frames of traditional Japanese residential houses. The deformation and failure characteristics, lateral load-carrying mechanism, and influence of the height aspect ratio on the lateral behavior of squat mud walls are investigated. We observed that when the height aspect ratio of the mud wall is less than 0.5, the initial failure is dominated by corner crushing rather than by shear failure. The lateral stiffness of the squat mud wall is positively correlated with the wall height, whereas the drift angle corresponding to the bearing capacity exhibits an inverse relationship with the wall height. For a height aspect ratio less than 0.3, the internal deformation of the squat mud wall is primarily driven by the deformation angle related to corner crushing and sliding. However, when the height aspect ratio increases to 0.5, the rotation angle increases significantly. The transformation of the deformation characteristics and internal force distribution of the squat mud wall depends on the interplay between the wall height aspect ratio and friction coefficient between the mud wall and timber frame. Drawing from comparative experiments and internal force analysis, the lateral resistance of the squat mud infill wall can be separated into two groups of elements: Qc and Qc’, stemming from the corner compression between the mud wall and adjacent timber frame or internal timber laths, respectively, which exhibits a significant positive correlation with the wall height; Qf and Qg, attributed to the frictional force of the protruding ends of bamboo laths and the gravitational force of the squat mud wall, respectively, which exhibit a consistent behavior unaffected by alterations in the wall height.