Seismic performance comparison of reinforced concrete portal frames with brick masonry and CLT infill panels

This study compares the seismic performance of reinforced concrete (RC) frames infilled with brick masonry and three-panel cross-laminated timber (CLT) under cyclic lateral loading. Two 1:4 scaled specimens were tested, and their lateral strength, ductility, and failure mechanisms were evaluated. The results reveal that brick masonry infills increase initial lateral capacity but alter the frame’s behaviour from flexural-dominated to truss-like. Significant diagonal strut forces develop within the infill, inducing additional shear at column ends and axial forces at beam–column joints, leading to premature column damage and reduced ductility. In contrast, CLT infill panels improve lateral resistance while preserving flexural behaviour similar to bare RC frames. The CLT-infilled frame exhibited superior ductility and safer failure mechanisms, with damage concentrated in the beams rather than the columns. Although brick masonry provided greater energy dissipation, CLT infill panels still offer considerable advantages for structures in seismic-prone regions due to their enhanced ductility and safer failure patterns.