Study On Length Of Shell Element Segment In Multi-scale Model Of Steel Structure

Steel structure is widely used in various buildings due to its good seismic performance.However,the seismic calculation model of steel structure lags behind the construction of steel structure.Establishing an accurate and efficient finite element calculation model is an urgent problem to be solved.At present,fiber model and shell model are mostly used for finite element analysis of steel structures,but both have disadvantages.Multi-scale model are favored by scholars as a newer finite element calculation model.Some scholars have done some work on multi-scale model.However,studies on the value of shell segment in multi-scale model have not been seen.The reasonable value of shell segment should cover the area where significant damage has occurred.This paper aims at how to determine the value of the shell segments in the multi-scale model and establish a more accurate multi-scale model.The main work and results of this paper are as follows:Taking the H-shaped steel column as the object,the fiber model,the shell model and the multi-scale model were established respectively,and the applicability of the three finite element calculation models was explored.The results show that the fiber model has high calculation efficiency,but when the structure is significantly damaged,the fiber model will underestimate structural response,resulting in large errors;the shell model is the finite element model with the highest computational accuracy,but its computational cost is high.The multi-scale model combines the advantages of fiber model and shell model,accurate and efficient,so it is a good choice to use multi-scale model for finite element analysis of steel structures.The influence of the existence of axial pressure on the ultimate bearing capacity of Steel column is explored.The analysis results show that the existence of axial pressure will greatly reduce the bearing capacity,which can not be ignored in the calculation.Taking H-shaped steel as the object,the effects of axial compression ratio,slenderness ratio,web height-thickness ratio and flange width-thickness ratio on the size of the damage area are studied when the steel column is subjected to the load perpendicular to the strong and weak axes.The corresponding damage areacalculation formula is proposed that as a reference for establishing a reasonable multi-scale model.According to the calculation formula of the shell segment proposed in this paper,the size of the shell segments is determined,and a multi-scale model is established for a three-layer steel frame.The actual seismic wave records are input,and the elastoplastic response analysis under earthquake action is carried out to analyze the structural response.The model analysis results are compared with the shell model to verify the rationality of the formula.