Study On Seismic Behavior Of Dry-laid Stone Masonry Wall Strengthened With "Double-layered Wall"

Stone masonry structure has a long history,it is still widely used in many areas.However,the integrity performance of stone masonry structure is poor,there is a big earthquake hazard on it.As important load-bearing and anti-lateral components in stone masonry,stone masonry’s reinforcement is very necessary.This thesis focuses on the common dry-laid stone masonry wall in Fujian province,the "double-layered wall" which means strengthening the stone masonry wall with steel-meshed cement mortar or reinforced concrete surface layer is proposed in order to resist the earthquake,and the studies are as follow:(1)Study on the reinforcement effect and its influencing factors of dry-laid Stone masonry walls which are strengthened with steel-meshed cement mortar.Static test study on nine dry-laid stone masonry walls were carried out.Three of these walls are dry-laid specimens and six are strengthened with steel-meshed cement mortar.The study parameters include masonry mortar strength,the number of reinforced surface layer,the thickness of the reinforced surface layer and the reinforced ratio of horizontal rebars.The results show that the shear capacity of dry-laid stone masonry wall is related to the strength of masonry mortar,and its shear capacity which is related to the number of pads and the degree of mortar saturation has lots of randomness;The reinforcement of the stone masonry walls with steel-meshed cement mortar can generally increase the shear capacity by one to three times,and can improve the ductility and lateral stiffness of the stone masonry walls;The role of rebars in shear loading is small;the displacement between the mortar surface layer and the stone masonry wall is coordinated before the specimen cracks.(2)Study on the reinforcement effect and its influencing factors of dry-laid Stone masonry walls which are strengthened with reinforced concrete surface layer.Static test study on three dry-laid stone masonry walls which are strengthened with reinforced concrete surface layer were carried out.The study focuses on two parameters,one is the number of reinforced surface layer,another one is the masonry mortar strength.The results show that the reinforcement of the stone masonry walls with reinforced concrete surface layer can generally increase the shear capacity by more than three times,and can improve the ductility and lateral stiffness of the stone masonry walls;the reinforced concrete surface layer plays a bigger role in this strengthening method than rebars.(3)The ABAQUS software was used to perform finite element analysis on stone walls and strengthened stone walls.The finite element model was established using the test specimen as a prototype.The influence of some parameters on the reinforcement effect was also studied on the basis of the model.The results show that when a zero-thickness contact element is used to simulate masonry mortar and mats between stone walls,a more accurate model can be established.Also,the simulation results show that the reinforcement ratio of vertical rabars have no effect on increasing the shear capacity of stone masonry wall,but material strength and thickness of surface layer can play a positive role.(4)Derivation of shearing capacity formula of strengthened stone masonry wall.The shear capacity of stone masonry wall strengthened with "double-layered wall"was calculated after comparing with the test phenomenon of brick masonry walls which were also strengthened with "double-layered wall".According to the comparison with the test results,the proposed formula that can be used for the design of stone masonry wall strengthened with "double layer wall" is obtained.