Study On Optimization Of Reinforcement Parameters Of Bottom Frame Masonry Mixed Structure Considering Uneven Settlement Of Foundation

With the advantages of short construction period,low construction difficulty and low cost,bottom frame masonry mixed structure occupies a large proportion in small and medium-sized urban buildings in China.For the bottom frame masonry structure based on natural foundation,under the influence of uneven settlement of foundation,due to the lack of resistance ability of the upper structure to it,wall cracking,component damage and internal force redistribution often occur,which will pose a threat to the service safety of the structure.However,the existing reinforcement design method of the upper structure has less consideration on the interaction between the upper structure and the foundation and the uneven settlement of the foundation before reinforcement,which makes the integrity of the structure has not been effectively improved,and the ability of the upper structure to resist the uneven settlement of the foundation is still insufficient.Therefore,based on the principle of common action,this paper adopts the method of combining numerical analysis and engineering example,establishes the relevant model by ABAQUS,and analyzes the parameters affecting the integrity in the reinforcement method of wall and bottom frame column,and further puts forward the reinforcement technology scheme of bottom frame masonry structure considering uneven settlement of foundation.The specific contents and conclusions are as follows:(1)The bottom frame masonry structure models of different foundation settlement types(the settlement of middle column is greater than that of side column and the settlement of corner column is greater than that of middle column)are established to analyze the influence of different floor wall stiffness parameters(elastic modulus and wall thickness)on uneven settlement of foundation.The analysis shows that increasing the elastic modulus of the wall and the thickness of the first wall can improve the uneven settlement of the initial foundation,while increasing the thickness of the wall of other floors will increase the uneven settlement of the foundation.The higher the floor is,the more obvious the increase effect is.(2)Establish the bottom frame masonry structure model of different foundation settlement types,and comprehensively analyze the influence of the number,location and section size of the bottom frame column reinforcement on the uneven settlement of the foundation.The analysis shows that for the case that the settlement of the middle column is greater than that of the side column,the four columns at the corner have the greatest impact on the uneven settlement of the foundation,followed by the eight adjacent columns,and finally all columns.For the case of corner column settlement greater than the middle column,the middle four columns have the greatest influence on the uneven settlement of the foundation,followed by the middle eight columns,and finally all columns;when the cross-section size increases to 550mm X 550mm,the influence of frame column on the uneven settlement of foundation under the two settlement types is the largest.(3)In view of the uneven settlement accident of a five-story masonry structure foundation,the causes and types of uneven settlement are analyzed in detail;combined with the influence degree of uneven settlement parameters of foundation,a comprehensive reinforcement scheme is proposed.Through on-site monitoring and engineering testing,the reinforcement effect of superstructure is analyzed and verified.The results show that the ground settlement curve obtained by numerical simulation is basically consistent with the law of actual engineering monitoring data,which proves that the reinforcement scheme has good applicability and can provide ideas and reference for the treatment of similar problems.