Experimental And Numerical Study On Dynamic Response Of Steel Beams Impacted By Drop Hammer At Elevated Temperatures

Steel structures are being widely used at home and aboard due to their own advantage.For instance,many landmarks are steel structures,and steel structure residences have also been extensively used.With the increase of steel structure buildings,relevant design theory and academic research are developing further.Specially,the fire and impact resistance performance of steel structures also attracts extensive attention of academia and engineering realm.For some important buildings,in addition to the conventional design load,it is necessary to consider the influence of the accidental loads,such as fire,impact and so on,within the serviceable life.Besides,the bearing capacity should be guaranteed while designing the structure.Beams are the main load-bearing members,and their resistance to the accidental load should be fully considered.By means of experiment and numerical analysis,the dynamic response and the lateral torsional buckling behavior of I-shaped cross-section beams under different fire temperatures and impacted by hammer is studied in this paper.The main research contents are as follows:(1)Experiment on restrained steel beams impacted by dropping hammer at elevated temperature environment are conducted.Under different temperatures and impact momentum,dynamic response of the two extreme constraints beams,that is fixed-fixed beam and hinged-hinged beam,is analyzed.To discuss the influences of temperatures,boundary conditions and velocity on impact resistance capacity of steel beams are discussed.(2)The experimental results are verified and compared by finite element software ANSYS/LS-Dyna.Based on the comparison of The deforming process and ultimate displacement of steel beams obtained by numerical analysis are compared with experimentalresults,and the simulation results are consonant with the experiment.This illustrates that it is viable to study the dynamic response of restrained steel beams at high temperatures by finite-element simulations.And this provide a basis for the parameter analysis conducted by numerical simulation.(3)A lot of parameter analysis is conducted by finite element software: under different temperatures,the dynamic response of steel beams with different supported conditions at its ends such as fixed-fixed,hinged-hinged and fixed-axial spring restrained;the displacement-time curve of steel beam under the combined action of temperatures and impact load;the impact force-time curves and the change laws of other related parameters at elevated temperatures.From the analysis of impact force-time history curve,the variation trend of maximum contact force with temperature is similar to the variation trend of the yield strength reduction coefficient of steel at different temperatures given by EC3.Furtherly,for influencing factors such as velocity of the dropping hammer and boundary conditions,a large number of related parameters analysis is also done.The above conclusions are of great significance for related research.