Mechanical Behaviour Of H-section Steel Columns During Impact And Their Damage Evaluation After Impact Loading

H-section steel members have many advantages,such as light weight,strong bending resistance,convenient assembly et al.The H-section steel members were usually employed as the key load-bearing elements in industrial buildings,which were vulnerable to the vehicle or crane-load collision.The impact may lead to structural damage or even loss of bearing capacity.Generally,when the damage is not serious,it is necessary to judge whether the damaged members could be used serve for economic reasons.Therefore,it is necessary to evaluate the residual bearing capacity and damaged state of members.In this paper,the performances of H-section steel columns during and after impact loading were studied experimentally and numerically,in which the coupling effect of the axial and impact loads was considered.The main work and achievements are as follows:(1)15 H-section steel columns were tested under lateral impact tests,and the residual bearing capacity of specimens subjected strong axis impact and 2 undamaged specimens were studied.The main parameters include impact energy,axial compression ratio and impact direction.The deformation shape,impact force,mid-span deflection,bearing capacity and surface strain of the specimen were obtained in the test.The test results showed that the deformation forms of the specimens bent along the strong axis after impact were overall deformation and local deformation,and the local deformation of the specimen bent around the weak axis after impact was not obvious.(2)The finite element models of lateral impact and residual bearing capacity of H-section steel columns were established.The dynamic and quasi-static analysis was carried out through ABAQUS/ Explicit dynamics module,and the models were verified through the test results.Based on the above analysis,the whole process of impact and post-impact of typical specimens was analyzed,including deformation form,deformation mechanism,stress state and equivalent plastic strain.The results showed that the development rate of global deformation was faster than that of local deformation.When the velocity between the specimen and the hammer head was zero,the lateral deflection and the stress at the mid-span reached the maximum values,and the upper part of the impact area yields.The equivalent plastic strain in the axial loading process after impact was concentrated in the impact area.(3)The main parameters affecting the dynamic response of H-section steel column members under impact load and the residual bearing capacity after impact were analyzed,including section type,impact location,impact energy and axial compression ratio.The results of parameter analysis showed that the increase of impact energy and axial compression ratio had an adverse effect on the anti-collision performance of the specimen.The residual bending deformation of 1/4 of the mid-span was smaller than that of the whole mid-span,and the residual bending deformation was higher than that of the mid-span.(4)According to the test and parameter analysis results,an empirical formula for evaluating the residual bearing capacity based on local deformation and overall deformation after impact was proposed,and the prediction results had high accuracy.