Simplified Calculation Model and Dynamic Characteristics Analysis of Modular Prefabricated Steel Frame Structure

Modular building, as the most prefabricated building structure system, has become a hot research topic in the construction industrialization with its significant advantages such as high degree of assembly, fast construction speed, less environmental interference, controllable module quality, excellent sound insulation, fire prevention, and thermal insulation performance, removable reuse, green environmental protection and so on. China has made some achievements in the research and application of modular buildings, but mostly of which focuses on the modular joints and components, which lacks the research on the overall performance of multi-storey or high-rise modular structures under wind, earthquake and other load conditions. Therefore, the design and analysis of the whole structure of modular prefabricated steel frame with plate-inner sleeve joints was carried out to study the seismic performance of the structure under earthquake.
In order to facilitate the overall structural modeling and analysis, the simplified calculation models of the joints were studied according to the structural forms and force transfer characteristics of the joints between modules, and the simplified calculation models of the modular plate-inner sleeve joints were proposed and compared with the corresponding solid model for rationality verification; MIDAS/Gen 2020 was used to establish the calculation model of modular steel frame structure to carry out the response spectrum analysis, and the calculation results were compared with the current national standard limits; the structural dynamic response of modular steel frame under earthquake was studied, and the seismic performance of the structure was analyzed by elastic and elastic-plastic time-history to discuss the yield mechanism and development of plastic hinges.
The results show that:1) The stress distribution and failure modes of the simplified models are the same as those of the solid models, the failure modes of the two models are modular beam yielding and plastic hinges failure at the end of beam, and the load-displacement curves of that are similar. There is little difference in the stiffness in elastic stage, and the initial stiffness of the simplified model is about 0.84~0.91 times that of the solid model. Under the same load, the displacement and deformation of the simplified model are larger; after entering the elastic-plastic stage, the yield load and ultimate bearing capacity of the solid model are greater than those of the simplified model, which verifies that the simplified calculation model is reasonable and safe. 2) The relevant mechanical performance indexes of the modular steel frame structure obtained by response spectrum analysis, such as periodic mode, vertex displacement, story drift ratio and stress ratio meet the requirements of seismic design, and the steel consumption of the structure is 84.02 kg/m², which is reasonable within the range of steel consumption. Therefore, the design of the whole structure is reasonable. 3) Through the elastic-plastic analysis, it is found that most of the structural components are still in the linear elastic stage under rare earthquakes, and only a few components reach yield.The plastic hinges are mainly concentrated at the end of the module beam, and the module beam yields before the module column, which indicates that the modular structure belongs to the system of "strong column and weak beam", and has good seismic performance under rare earthquake.