Improving the out-of-plane flexural behaviour of the FRP strengthened masonry walls
Unreinforced masonry (URM) structures have a low resistance against lateral loading and are vulnerable to earthquake and wind effects due to their low flexural capacity and relatively brittle mode of failure. Strengthening of the masonry walls against lateral loading usually aims for increasing their load bearing capacity and ductility. The application of fibre reinforced polymer (FRP) composites as externally bonded reinforcement in repairing and strengthening of masonry walls has become more attractive than the traditional methods. Determination of the flexural out-of-plane behaviour of FRP strengthened masonry walls with different types and configurations of FRP composites is the main objective of this research. Experimental program has been developed including small-scale and large-scale experiments. In addition, theoretical finite element (FE) modelling has been developed and verification of the models via comparison with, experimental results is conducted. Small-scale experiments are designed to measure the mechanical properties of masonry and mortar samples. As a result, the values of elastic modulus and compressive strength has been evaluated and used as material properties for the FE model. For large-scale experiments, seven specimens of masonry walls were constructed with clay bricks and mortar. Six samples were constructed as thin masonry walls with 1/2 brick thickness equal to 102.5 mm and one full brick thick sample was constructed with 215mm thickness. The walls are strengthened with different types and configurations of FRP materials. The specimens are subjected to uniformly distributed lateral load, applied by an airbag, on one side and over the whole surface of the wall. Theoretical FE models are developed using ANSYS software and are verified via comparison with the experimental results. Further analysis on the behaviour of FRP, strengthened walls have also been conducted. The results show that the use of FRP strengthening has increased the out-of-plane capacity of URM walls by almost 3 times and significantly improved the ductility of the walls. The comparison of the load-deflection graphs from the theoretical modelling with the corresponding results from experimental investigation shows good compliance in elastic range of loading.