Research On Seismic Behavior Of Reborn Concrete Brick Walls And Structure Under Acidic Atmospheric Environment And The Methods For Nonlinear Analysis

With the development of economy and technology, the traditional masonry structure is gradually being replaced by frame and shear wall structure, but it is still one of the main structure form in our country with a large number and wide area, also it will exist for a long time especially in the rural areas.However, due to the difference of the weak seismic performance and construction control of masonry itself,it makes the seismic fortification situation of existing housing not satisfied. And the durability of civil masonry buildings is changed as time goes by after a long time of service.At the present stage,there are lots of masonry structure building and historic buildings.They withstand long-term erosion of acid rain in acid atmospheric environment, therefore setting up the attenuation law of seismic performance of masonry structurein the harsh service for many years will have significant influence on our civil building assessment in present service and ancient architecture protection.In this paper,through the acid rain corrosion tests in different degree and low cyclic loading tests on 8 specimens of recycled concrete brick masonry wall with the same characteristics, the failure form and stress performance of recycled concrete brick wall are observed and analyzed,then it obtains the performance degradation characteristics(such as deformation, hysteretic behavior, ductility and energy dissipation properties) that recycled concrete brick masonry composite wall shows with the increase of corrosion cycles, and reveals the seismic damage evolution lawof concrete brick masonry composite wall under different cycle system,finally, based on material damage theory and test results, damage restoring force model of brick masonry structure is established, which provides experiment basis for nonlinear seismic analysis and durability evaluation of masonry structures in service under the influence of acid atmospheric environment.As a necessary means of research, finite element numerical analysis can effectively evaluate the seismic performance of masonry structure. But as brick and mortar are two different kinds of materials, it is difficult for us to grasp its discreteness from the limitation of masonry structure. Aiming at the problem about finite element numerical simulation of masonry, this paper adopts the equivalent frame model and three spring model to make a modeling analysis of masonry structure.The results show that the model of truss model has good accuracy, but cannot reflect the basic dynamic response of structure,although it will inevitably cause the differences of mass distribution by using three spring element,but each modal dynamic characteristic is similar to entity unitalong the main direction of the wall, which can think three spring unit can accurately reflect the basic dynamic characteristic of masonry structure, and meet the requirement of nonlinear dynamic time-history analysis under the action of earthquake.Finally, model based on the layer model and the IDA method is applied to seismic vulnerability analysis, then the limit value of masonry structure under the limit state is concluded, and draws the seismic vulnerability curve through curve fitting. Based on the structure under the action of minor earthquakes, and major earthquakes in the vulnerability of comparative analysis, it shows the code of “no damage in Minor Earthquakes” and, “repairable in major earthquake” in basic can be reached with the increase of structural damage, but the masonry can not satisfied with seismic resistance regulations in a larger cycles of acid rain that had an adverse effect on structure collapse resistance.