Augmenting the seismic performance of unreinforced masonry loess - Cave with composite materials through shaking table testing

Abstract

To improve the seismic performance level of existing masonry buildings, a composite reinforcement method of polypropylene packaging strap (PP) and cement was used to design unreinforced masonry loess-cave (URML) structural models with a scale ratio of 1:4, and shaking table tests were conducted on these models. Reinforcement measures were used to reinforce the earthquake-damaged URML structure, and vibration table tests were conducted again on the reinforced URML structure using the same loading procedure. A comparative analysis was conducted on the failure modes, acceleration response, displacement response, torsional effect, and energy dissipation capacity of two model structures under earthquake action, and their seismic performance was evaluated. The experimental results show that the overall seismic performance of the URML structure is poor, with a low natural frequency, large displacement response, and obvious torsional effect. It is close to collapse under the PGA = 0.8 g earthquake action; the model (RML) structure strengthened with PP strap and cement combination has an increased natural frequency, smaller displacement response compared to the unreinforced model, and it has a significantly controlled crack propagation. The destructive effect of the structural torsion effect is significantly reduced. Under the PGA = 0.8 g earthquake, only slight damage occurs to the water mud surface layer. The combination of the PP strap and cement reinforcement method can effectively delay the stiffness degradation of URML structures under strong earthquake action, increase the damage resistance of the structure, and effectively improve the overall seismic resistance of such masonry structures.