Research On The Mechanical Properties Of Modular Steel Frame Based On Multi-scale Finite Elements

The prefabricated modular steel structure building has the advantages of high construction efficiency,short construction period,high degree of factory prefabrication and green environmental protection.China vigorously advocates the development of building industrialization,and the research on prefabricated modular steel structure has also rapidly developed into a frontier research field.prefabricated modular steel structure is a widely used prefabricated structural system.At present,the research on prefabricated modular steel structure in China mainly focuses on the joints between modules.As an important part of the modular structure system,the reliability of the joint connection between modules is the key factor to determine the mechanical performance of the modular structure.In engineering design,the structural details of the joints between modules are usually ignored and simplified as rigid or hinged joints,which may lead to the fact that the mechanical properties of the whole structure cannot be truly reflected in the calculation and analysis process.Although all solid element modeling can more accurately reflect the mechanical properties of the modular overall structure,this modeling method has low computational efficiency and requires a lot of computer resources.Therefore,in this paper,the static and dynamic analysis of modular steel frame structure is carried out by multi-scale modeling analysis method,and the influence of calculation analysis method and joint structure type difference on the mechanical properties of modular steel frame structure is discussed.The main research is as follows:(1)Based on the plate-inner sleeve joint as the research object,according to the actual structure of the modular building structure node,the multi-scale,solid element and beam element models are established.By comparing the load-displacement curves and node stress distribution of the three calculation models,it can be seen that the stress distribution and maximum stress of the multi-scale and solid element models are basically consistent,and the load-displacement curve trends of the two are basically the same,which verifies the reliability of the multi-scale model.(2)The finite element software ABAQUS is used to establish a multi-scale plane steel frame model for static analysis,and the solid element and beam element models are compared to obtain the internal forces of the module beams and columns under the three calculation models.The calculation results show that the calculation results of the beam element model are discrete and unstable.Compared with the beam element model,the calculation results of the multi-scale model are less discrete,and the calculation results tend to be stable.The internal force difference between the multi-scale and the solid element model is small,and most of the errors are less than 2%,indicating that the two have considerable calculation accuracy.In addition,compared with the solid element model,the computational efficiency of the multi-scale model is improved by about 40%.(3)Based on the 6-story prefabricated modular residential building,the multi-scale and beam element models are established to analyze the dynamic time history under rare earthquakes.The dynamic response of the multi-scale and beam element models with the change of floors is discussed.The top floor displacement,floor displacement and inter-story displacement angle of the multi-scale and beam element models under different floors are obtained.The research shows that when the number of modular structure layers is 10 or less,the difference between the beam element model and the multi-scale model is small.The prediction of the weak layer location of the modular structure by the two models is the same,but the calculation results of the beam element model are not stable enough.When the number of modular structure layers exceeds 10,the calculation accuracy of the beam element model is greatly reduced,while the calculation accuracy of the multi-scale model is stable.(4)In ABAQUS finite element software,modular plane steel frame models with plate-inner sleeve joint,blind bolt joint,and rotary inter-module connection joint were established respectively.Modal analysis and dynamic elastic-plastic time-history analysis were performed on the three models,and the frequency,period,top-level displacement,floor displacement and inter-story displacement angle of each model were extracted.The research shows that: The structural type difference of the joints between the modules has little effect on the natural vibration period of the modular structure,and has no obvious effect on the vibration mode of the modular structure,but has a great influence on the dynamic response of modular structure under rare earthquakes.The maximum difference in the dynamic response of the modular structure with different joint structural types is 33.29 %;compared with the MGKJ-TT model,the inter-story displacement angles of MGKJ-LS and MGKJ-XZ models under rare earthquakes exceed the limit of "medium damage".It is recommended to strengthen the inter-story stiffness of the structure during engineering design to improve the seismic performance of the structure.