Research On Properties For Steel Frame Under Impact Loading

It had been ten years since the "9. 11" accident took place. The dead had passed away but the influence still remained for a long time. So in the process of drawing lessons from the past, the academia takes an growing interest in the research that how the large buildings collapse under the destruction of impact loading and at the same time it become a brand-new topic. On the other hand, steel structures occupy large and irreplaceable proportion in huge building structures field. And through studying and summarizing this research program, it is of great realistic significance as the subject of steel structures.This thesis will perform an emulated analysis by using the finite element of software ABAQUS, aiming at the project of the dynamic response that the steel structure joints take under the impact loading as the theme and content of the research.Firstly we will analyze and perform simulation of the dynamic response that the steel structures take under impact loading in this thesis. Because of the relatively high strain rate of steel components in the process of the impact, this thesis takes the effects of the strain rate into consideration in choosing constitutive materials, for the strain rate depending on material strength. Assuming that beam-column joints do not occur to damage, this thesis will make the instructions of the modeling feasibility and the calculation rationality through the analysis of the response of the structures.Secondly eighteen finite element model will be established due to three factors that are the part of impact beam,the initial velocity of the impact objects and the elastic modulus. Otherwise the impact loading should be determined through the exploring the factors under all sorts of the influence, and the discussion in detail will be made on beam effects of the above factors on the basis of the calculation result, including distribution regularities of cross-sectional stress of the beam ends and the vertical displacement of the beam.Finally, there is a simulated comparative study on three types of the nodes thart are ordinary type, dog-bone and web opening. The thesis contains the variation of these three categories of nodes in the process of impact ends, focusing on analyzing the maximum stress between the beam-end and weak the girder ends, strain and the vertical displacement of the beam. At last from comparative data it is shown the dog bone type node does best in postponing the department of the destructiveness of the beam in these three types of nodes, while webs myriapod does not play a significant role.