Resistance functions for blast fragility quantification of reinforced concrete block masonry shear walls

Reinforced masonry shear wall (RMSW) systems constructed using concrete blocks are widely used within the current North American construction practices. The limited research carried out on the performance of RMSWs under blast loading has reviled their high vulnerability. This study evaluates the blast performance of such loadbearing and non-loadbearing RMSWs considering the variability associated with different blast wavefront parameters, specifically the positive specific impulse and the peak reflected pressure. In this respect, a concentrated plasticity model is created using OpenSees that simulates the out-of-plane behavior of RMSWs. The model is first validated both statically and dynamically using different experimental datasets. Afterward, the model is utilized within an iterative framework to track the strain rates of different RMSW constituent materials, thus extracting the corresponding dynamic increase factors. Finally, the developed model is used to generate fragility curves and surfaces considering the expected variability/uncertainty in blast wavefront parameters on the response of RMSWs with different axial stress levels and reinforcement ratios. The proposed fragility quantification approach paves the way to develop new blast risk assessment tools for the next generation of blast-resistant construction standards.