• Investigating the Effects of Toothed Edges and Large Openings on the Seismic Behaviour of Confined Masonry Walls

Confined masonry structures are commonly seen in seismically active regions in developing countries, due to their satisfactory performances in past earthquakes, cost effectiveness and ease of construction. However, confined masonry construction is a less researched field compared to other techniques which are more commonly used in urban areas, such as reinforced concrete construction. As a result, relevant codes are less extensive, and best-practices that builders rely on can be ambiguous or contradictory.

This experimental study is conducted in response to a research request from Smart Shelter Foundation (SSF), an NGO building earthquake-proof structures in Nepal, to find out more about the effectiveness of the methods they have adopted.

In this experiment, 3 confined masonry specimens were constructed based on SSF’s designs, to investigate the effectiveness of toothed wall-to-column connections, as well as the effects of a large opening in the masonry panel. Each specimen was subjected to displacement controlled in-plane cyclic loading for 2 cycles per drift at 1.0% increments, until a 20% drop in maximum strength was attained.

Experimental work showed that toothed wall-to-column connections did not provide significant improvement to the in-plane seismic response of the wall panel, and a non-toothed connection may be sufficient. Tests also showed that large openings allowed more deformation, thus increasing energy dissipation capacity. Furthermore, provision of a lintel band above an opening in the upper-middle section of the panel may alleviate the detrimental effect of the opening on wall response. Specimens first showed signs of flexural cracks on the reinforced concrete frame, followed by development of multiple diagonal cracks on the wall panel, which contributed greatly to energy dissipation. For all specimens, cracks were well-distributed over the masonry panels.