Numerical Simulation On The Mechanism Of Roof Cracks In Masonry Building With The Influence Of Different Vertical Loads

With the predominance of economical cost,convenient construction, using local materials,and so on,Masonry structure is one of the most commonly used structural forms in China. Meanwhile,masonry materials have the disadvantages of low tensile and shear strength,and so forth,which easily lead to the appearance of cracking phenomenon in masonry wall.It has become the program of common concern of engineers and technicians,inhabitant, administration department,etc.Among them, inclined crack produced by different vertical loads in the top of masonry walls is a new issue demanding prompt solution.For this reason,numerical finite element method was used as simulation means in this paper in order to study the stress performance and the crack mechanism of masonry structure which was suffering from different vertical loads.Firstly, the classification and the causes of masonry crack were introduced in the paper, including the reason of crack induced by different vertical loads.The theoretical analysis and calculation method of such cracks were mainly investigated using elastic mechanics methods,simplified calculation methods and finite element methods.Secondly, non-linear finite element theories were summarized.A detailed analysis and discussion of the difficulties faced in finite element analysis was performed,such as the elements selection, material constitutive relation, failure criterion,convergence criteria and so on.The properties of SOLID65 element, which is commonly applied for finite element analysis of masonry structure,were also presented in this part.Thirdly, by means of integrated model,the finite element software ANSYS was used to study on elastoplastic behavior of the walls constructed to 1/2 ratio.The applicability of SOLID65 element for analyzing such cracks was also studied.Then the general FEA program ANSYS was adopted to analyze the six-story masonry building constructed to 1/4 scale.The fracture distribution, fracture morphology and displacement variations gotten from analysis have a good agreement with theoretical analysis results and test results.In the simulation process,the advantages of finite element software were made full use of to expand the scope of analysis.The influence on mechanical behavior and crack condition of the structural height,constructional measures,width of bearing walls,masonry material properties,etc.,has been studied.On this basis,preventions and repair methods of such cracks were studied.This thesis emphasizes to study the stress calculation method for walls with structural measures suffering from different vertical loads,establish economy, reasonable model and select appropriate parameters to simulate the test.Meanwhile, the stress performance of models under various working conditions has been analyzed by changing parameters,which made up for the deficiency of test and made some beneficial exploration for study on fracture of masonry walls bearing different vertical loads.