Enhancement of lateral in-plane capacity of partially grouted concrete masonry shear walls

• Double reinforcement resulted in significantly improved seismic performance.
• Partially grouted masonry walls behave similar to infilled-frames.
• Doubling the grouted cells has a small impact on the construction cost and effort.

The goal of the research presented herein is to investigate a new approach to the reinforcement of partially grouted walls, double side-by-side reinforced cells, in order to enhance the seismic performance of such walls. Specifically, the results from the destructive tests of three cantilever full-scale square masonry shear walls are presented. The control wall was constructed using the conventional single cell reinforcement (SR) approach, with the remaining two walls constructed using double cell reinforcement with bond beams (DR), and with the addition of bed-joint reinforcement (DR-JR), respectively. To permit direct comparison, the total amount of reinforcement in the SR and DR walls was held constant. The experimental investigation indicated that the DR reinforcement approach resulted in significantly improved lateral in-plane response compared to the conventional SR approach. Specifically, the DR wall exhibited a 34% increase in shear capacity and 47% increase in displacement ductility. To investigate the effect of grouting on the response of proposed reinforcement details a numerical modeling technique was developed based on the infilled-frame concept and calibrated with the experimental behavior of considered walls. It is evident from the results of numerical modeling that response of walls is in a good agreement with the behavior observed in the experiments. Numerical model showed that the behavior of grouted and ungrouted parts of PG walls are similar to a frame and an infilled, respectively. Grouting double side-by-side cells enhances the frame action of grouted masonry parts and also provides a better confinement for the infilled masonry. As a result of the strengthened frame the performance of wall DR was improved significantly compared to wall SR.