Research On Analysis Method Of Equivalent Frame Model Of Reinforced Masonry Structure

Masonry structure will exist for a long time in the process of rural revitalization in China.However,it is very difficult to analyze unreinforced masonry structures because of the discreteness of masonry materials,non-standard construction and difficult problems in wall analysis.As a low-cost and more accurate research method,finite element modeling analysis has led scholars to research on masonry structures more quickly and conveniently.At present,there are two modeling methods for masonry structure,one is fine modeling,the other is integral modeling.Fine modeling has the advantages of high precision and accurate analysis results,but the modeling is complex and the calculation speed of the model is slow,so it has high requirements for computers.The integral modeling method is simple and the model is easy to converge.Although the calculation accuracy is not as high as the separated one,it can achieve the accuracy needed by the engineering practice.Therefore,at the present stage,most of the masonry structure modeling uses the integral method,and the equivalent frame method is one of the integral modeling.In the equivalent frame method,the material is assumed to be a homogeneous and isotropic ideal material.Therefore,compared with other modeling methods,the material mechanical parameters required by the equivalent frame method are simpler and the modeling is more convenient.In this paper,the equivalent frame analysis model of unreinforced masonry structure is established by establishing and perfecting the equivalent frame analysis model of unreinforced masonry structure,and on this basis,combined with quasi-static test,the equivalent frame model of reinforced masonry structure is established,which provides theoretical support and scientific suggestions for the reinforcement of damaged masonry structure.The main contents of this paper are as follows:(1)The foreign equivalent frame model modeling methods of masonry structure are summarized as a whole,and the existing equivalent frame model of masonry structure is established.(2)The overall analysis of spandrel and beam is carried out,and the formula for calculating the overall stiffness between spandrel and beam is obtained through theoretical derivation and simulation analysis.(3)Bring the above calculation formula into the equivalent frame model to verify whether it is consistent with the test results,so as to establish an equivalent frame model which is suitable for masonry structures in China.(4)Through the combination of experimental research and simulation analysis of masonry substructure,the equivalent frame model of damaged and strengthened masonry substructure is derived.the equivalent frame model of damaged and strengthened wall substructure under masonry window is deduced.The research results of this paper show that:(1)Considering the influence of the beam on the opening on the masonry structure when the equivalent frame method is used to model the masonry structure,spandrel and beam are regarded as composite component,and the stiffness of spandrel element in the equivalent frame model is modified from the point of view of elastic modulus.The equivalent elastic modulus of composite component is verified by theoretical derivation and numerical analysis.(2)The ultimate bearing capacity of the equivalent frame model is positively related to the ultimate shear force and the ultimate bending moment of the plastic hinge;the initial stiffness of the equivalent frame model is positively related to the length of the rigid domain and the elastic modulus of the material.(3)The equivalent frame model of the damaged masonry substructure is established through the comparative analysis of the quasi-static testing before and after the breakage of the substructure.Through theoretical derivation,it can be concluded that the ultimate resistance force,ultimate bending moment and elastic modulus of the masonry substructure wall under the window,which characterized by the spandrel before piers failure.The equivalent frame model of reinforced masonry structure is further improved.The reinforcement equivalent frame model is not only applicable to the reinforcement of the steel wire mesh surface layer,but also applicable to other reinforcement methods.