Experimental Study On Sesmic Behavior Of Stone Masonry Walls Strengthened By Mounting Bars In Bed Joints

With the following advantages such as low cost, good durability, elegant appearance and so on, stone sturcture is favored by the people. It is one of the main structure forms of village buildings in the south and east of Fujian province. Because of its structure and construction characteristics, stone masonry is weak in structural integrity and seismic performance. It is necessary to strengthen the stone masonry walls. A new approach to strengthen stone masonry walls by mounting bars in bed joints is proposed. The shear behavior of stone masonry joints strengthened with polymer mortar and the seismic behavior of stone masonry walls strengthened by mounting bars in bed joints is investigated.In order to investigate the shear behavior of stone masonry joints strengthened with polymer mortar, thirteen non-strengthened control walls and twenty-one walls strengthened by filleting with polymer mortar in bed joints were tested under double shear, and the strengthening effects on the shear behavior with different kind of mortar, different motar strength and different compression stresses were investigated. It is indicated that the resistant process of bed joints in stone masonry consists of three stages: elastic stage, crack development stage and friction energy dissipation stage. The stone masonry had good capacity of energy consumption. The strengthened walls had higher shear capacity and shearing deformation capacity than the controlled specimens. The effect is more obvious when the compression stress is low and the mortar strength is relatively high. A formula to calculate the shear capacity of the strengthened stone masonry joint is proposed based on the test data and the calculated results show good agreement with the tested ones. It can be referenced for engineering pratice for seismic repointing of stone masonry structures.Six stone masonry walls strengthened by mounting bars in bed joints and one non-strenthened control wall were tested under low cyclic loading to investigate the seismic behavior of stone masonry walls and the effectiveness of the proposed strengthening method, patameters such as compression stress and different repointing forms were considered. According to the experimental study, failure mode, hysteretic curves, skeleton curves, energy dissipation and deformation behavior of specemens were analyzed. It is indicated that: (1) the crack strength and the ultimate bearing strength of the strengthened wall and its overall seismic performance is increased remarkably; (2) the steel bars mounting in bed joints can remarkably increase the shear strength of stone masonry walls, restrain the development of wall cracks, even change the failure modes, but it contribute little to the deformation of the wall.(3) all specimens had plump hysteretic loops, good capacity of energy dissipation. The shear capacity show slow decline in the late loading.(4) based on the experimental and analysis results, a formula to calculate the ultimate lateral shear capacity of the stone masonry wall strengthened by mounting bars in bed joints is proposed.At last, based on the test results, restoring force model and trilinear skeleton model of the stone masonry strengthened by mounting bars in bed joints is proposed, and hysteretic rule considering stiffness degeneration is also maked.