Experimental Research And Analysis On Full-scale Walls Of A New Rocking Masonry Structure

The rocking mode of unreinforced brick wall is formed owing to bending-tensile cracks under earthquake action,and it belongs to ‘displacement control' mode.The influence factors on the seismic failure mode of brick walls are analyzed in this paper,and two constructions,which are ‘inside groove' and ‘vertical isolation joint',are provided to change the failure mode of brick wall from ‘force control' mode to ‘displacement control' mode.Based on the ‘vertical isolation joint' construction,a seismic system named ‘new rocking masonry structure' is provided.In view of ‘new rocking masonry structure',experimental study on four full-scale masonry walls and numerical analysis are conducted in this paper.Main research work and results are as follows:(1)Comparison on the internal force calculation and the bearing capacity calculation of masonry walls,which provided by Chinese code,American code and European code,are conducted.Although there is a great difference on the calculation model and formulas between American code and European code,but the bending moment is considered in two codes,and that is worth considering for Chinese code.(2)The strength theory of rocking brick wall is studied,and the first cracking strength formula of rocking brick wall is provided.This paper provides a method to improve the bearing capacity and energy dissipation capacity of rocking brick wall by using constructional column.The bearing capacity formula of rocking brick wall with constructional column is provided.Based on the deformation theory of reinforced masonry walls,the displacement model and calculation method of rocking brick walls with a constructional column are provided.(3)Two constructions,which are ‘inside groove' and ‘vertical isolation joint',are provided to change the failure mode of brick walls from shear mode to rocking mode.Based on the ‘vertical isolation joint'construction,a seismic system named ‘new rocking masonry structure' is proposed,which consists of the upper conventional storeys and the lower rocking storeys.The ‘vertical isolation joint'construction is applied in the rocking storeys,and the conventional construction is applied in the rocking storeys.(4)Two full-scale brick piers test on the ‘inside groove' construction are conducted by quasi static method,and the transfer from diagonal tension mode to rocking mode by the construction was proved.Although the lateral bearing capacity of the wall with ‘inside groove' is reduced,but the energy dissipation capacity and deformation capacity are significantly improved,and the displacement ductility is also increased.(5)Two full-scale brick piers test on the ‘vertical isolation joint' construction are conducted by quasi static method,and although the lateral bearing capacity of the wall with joints is reduced,but the transfer from shear mode to rocking mode is achieved.Compared with the rocking unreinforced brick wall,the rocking brick wall with a constructional column appears excellent seismic capacity,which consists of high bearing capacity,high displacement ductility,high energy dissipation capacity and high self-centering capacity.(6)Based on ABAQUS program,a simplified mesoscopic model of masonry is proposed,and which is verified through numerical simulation of existing experiments.This paper presents a damage constitutive model of masonry subjected to axial monotonic and cyclic compressive loading.In order to get fine lever models,double parameters which consist of the peak compressive strain and strength were adopted to adjust the deformation curve.(7)The simulation results of test specimens show that both the fine model and the global model are succeed in simulating the failure mode of masonry walls,and the simulation results are basically consistent with the experimental results.The modeling method of integral wall + wall/floor interface contact is used to establish three-story rocking masonry structure model,and the simulation results show that the rocking model achieved the expected rocking deformation under lateral load,the hysteresis curve appears high earthquake-resistant capacity with self-centring feature.The study has been funded by following units: the Natural Science Foundation(50978177),the Natural Science Foundation of Shanxi Province(20110313026-3).