Experimental Study On Skeleton Curve Of Masonry With Brick Wall Reinforced With Mortar Splint

Masonry structure is widespread in China,especially in the vast rural areas they are still the priority choice for residential purposes.However,due to the situation that these structures are generally old,there will be certain defects in the materials and the structure itself,so it is urgent to carry out seismic strengthening plans.The cement mortar surface-layer reinforcement method is convenient in construction and low in cost,and is currently one of the most widely used methods.Although it has obvious advantages,but the related research is still not systematic,and the research results obtained also lacks a certain degree of unity.Therefore,in this paper the seismic performance of masonry brick walls reinforced by this method is studied.On the basis of summarizing previous studies,this paper proposes further research directions.Based on the pseudo-static test data before and after the reinforcement of a total of89 masonry brick walls,the failure modes,crack development characteristics,force-displacement hysteresis curves,and the shape characteristics of the skeleton curves of the wall before and after reinforcement are analyzed.At the same time,the influences of test parameters such as cement mortar strength,reinforced surface layer and vertical compressive stress on the wall skeleton curve were analyzed as well.Based on the nine types of combined failures that occurred in the reinforced walls during the test,the calculation formulas of the skeleton curves were fitted and verified with the test results.The main failure modes of the wall before and after reinforcement include four kinds:shear failure,sliding failure,bending failure,and baroclinic failure.The first obvious crack in each failure occurs basically at the side seams and wall surfaces where the wall and the bottom beam are jointed.The shape of the hysteresis curve of the wall before and after reinforcement is roughly presented in three types,namely spindle shape,bow shape,and S shape.The spindle shape has the best of fullness,and the seismic performance of the corresponding wall is most optimal;the fullness of the bow shape is slightly poorer,and the seismic performance of the corresponding wall is also weaker;The S-shape has the worst seismic performance due to the significant bending of the wall during the test.There are different forms of damage in the wall,therefore results different shapes of the corresponding skeleton curve.The most obvious difference is that when the shear failure and baroclinic failure occurs,the skeleton curve of the wall has a significant decline,and the rest types of failure hasn't.Through the analysis of experimental data,it is found that increasing the strength of wall masonry mortar can significantly improve the bearing capacity,the deformation capacity and the seismic performance of the wall.After the wall is reinforced with cement mortar,the seismic performance of the wall is apparently better than that of the unreinforced ones.Increasing the vertical compressive stress of the wall can increase the horizontal bearing capacity of the wall,but at the same time it will have an adverse effect on the ductility of the wall.Based on the experimental data,the skeleton curves of walls with different failure types were studied.The calculation formulas of the skeleton curves were fitted respectively,and compared with the curves obtained from the experiments,The results showed a highly compatibility and which could provides a certain references for the application of actual projects.