| With the development of building industrialization,box modular building has been developing rapidly in recent years with the characteristics of high prefabrication rate and green environment protection,taking standardization of design,quality of components,assembly of construction,integration of decoration and informatization of management as its standard.Compared with the traditional buildings represented by labor-intensive construction,modular construction has many advantages.The complete pipeline not only brings high construction efficiency and reduces the adverse effects of field operation,but also creates a new construction method-field splicing with box-type module units as the main part and connection as the auxiliary part.Although the benefits of modular buildings far outweigh the disadvantages,there are still several problems that are difficult to solve: firstly,there is no connection between modules that can be quickly constructed and reliably connected,which will increase the difficulty of field connection and affect the overall stability of the structure;secondly,the static and dynamic analysis of the whole modular building is still inadequate,and the stiffness and bearing capacity of joints and wallboards can not be fully considered.These problems lead to the fact that domestic research in this area is still in a slow stage of development.This paper puts forward some assumptions in view of the existing problems,so as to promote the development of modular architecture.Firstly,this paper briefly introduces some existing modular forms of modular architecture and three-board system for modular units,designing cable-buckle joints and spring-buckle joints for rapid connection of modular units,and designs a kind of box model for quick replacement components in Revit software based on the current mainstream concept of BIM building information modeling.Secondly,a simplified static calculation method for modular buildings is proposed by using the repeatability of modular elements and the condensation of degree of freedom of nodes.Because the calculation method needs to obtain the stiffness of joints,the process of calculating the stiffness and bearing capacity of joints is carried out.Two kinds of finite element models of joints are established.The material constitutive,loading system and boundary conditions are determined.The rationality of the finite element calculation is verified by referring to the real experimental research.The deviation between the finite element calculation results and the experiment results is less than 12%.The same calculation method is used to analyze the joints.Comparing the mechanical properties of two types of joints in three translational directions,a node with better performance is obtained as the basic joint for the following analysis.Through monotonic loading and cyclic loading simulation,the initial stiffness,ultimate bearing capacity and ductility of the joints under different parameters are obtained.The results show that under monotonic loading the comprehensive performance of the joints is optimal when the height ratio of the roof is 0.55 and the width ratio of the side plate is 0.7.The corresponding initial tensile stiffness is 2372.01kN/mm,and the lateral stiffness of the vertical cable side is 1660.63kN/mm.The stiffness of cable side before welding is 166kN/mm(after welding is 5639.8kN/mm).Cyclic loading simulation is carried out for a class of joints with good ductility.The hysteretic curve,skeleton curve and energy dissipation coefficient are obtained.The results show that although the initial stiffness and load-bearing capacity of the joints are high,their seismic performance is weak.So reinforcement and improvement should be carried out on cable-buckle joint in actual uses.Finally,the static and dynamic properties of modular buildings are analyzed.The initial stiffness and ultimate bearing capacity of the joint obtained by ABAQUS finite element method and the simplified equivalent single bar of the exterior wallboard are equivalent into MIDAS.The modal analysis,response spectrum analysis and elastic-plastic time-history analysis of the modular buildings with cable-buckle connection joint and rigid joint are carried out.The results show that the enclosure wall has a great contribution to strengthening the lateral stiffness of the structure,which can be increased by about 1.5 times;the structure with cable-buckle connection joint can be applied to 6 stories or less,and the structure with rigid joint can be applied to 1-8 stories;the structure with different joints has different plastic hinges in the elastic-plastic time history.The structural plastic hinges of rigid joint modular structure first appear on the floor beam while the plastics hinges of cable-buckle connection joint modular structure first appear on the ceiling beam,which leads to the difference of damage sequence and energy dissipation capacity between the two structures.The structure with rigid joint connection is superior to the structure with cable-buckle connection joint in seismic performance,but neither of them can give full play to the energy dissipation capacity of beams.Therefore,in order to improve the seismic performance of the structure,modular buildings should restrict the upper and lower beams as much as possible to make them coordinate the force and deformation. |
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