Compression behaviour of reinforced masonry walls: An investigation on the effects of lateral restraining methods

Compressive behaviour of reinforced masonry (RM) block walls is affected by the position of vertical bars inside the grouted cores and their lateral restraining methods. The current Australian Masonry Standard (AS3700-2018) specifies the contribution of vertical bars in the compressive strength of RM walls if the bars are surrounded by a grout annulus of a radius of at least two times the vertical bar diameter. However, without any lateral restrainers, it is difficult to position the vertical bars in the middle of the grouted cores to satisfy the grout annulus radius requirement, while the use of tie bars for restraining the vertical bars laterally is challenging and is not usually adopted on the construction sites. In this research, plastic restraining chairs have been employed in the construction of RM walls to restrain the vertical bars laterally in the middle of the grouted cores and their influence on the compressive behaviour have been evaluated. In total, eight RM walls were tested under concentric and eccentric compression loadings; of them, six walls were constructed with plastic restraining chairs, while two walls were constructed with lateral tie bars. Experimental results are presented in terms of the observed failure modes, compressive strengths, and the axial strain variations in the vertical bars. It was observed that the plastic chairs were able to restrain the vertical bars into position without compromising the compressive strengths in comparison to the walls where vertical bars were tied with the lateral bars.