Experimental And Theoretical Study On Flexural Performance Of Fixed Supported Hollow Steel Beams

Hollow steel beams have advantages such as reducing floor height and structural weight,and attractive appearance,so it is widely used in modern architectural structure.The mechanical properties of hollow steel beams are influenced by various factors such as end distance,hole length-to-height ratio,hole height ratio,opening ratio,and opening distribution.Current research has paid little attention to the mechanical properties of hollow steel beams with fixed ends.Therefore,it is necessary to investigate the influence of these factors on the mechanical properties of fixed hollow steel beams.By means of experiment and numerical simulation,this paper studies the flexural capacity and stiffness of hollow steel beams.The main work and conclusions are as follows:1.The test results showed that the failure mode was similar to that under simply supported conditions.Four plastic hinges were formed around the hole which were respectively strained and compressed when the failure occurred.The results of comparison between test and simulation show that the support used in the test cannot reach the ideal fixed support,but the yield load and ultimate load were close to the simulation results.2.The position of the openings has a significant effect on the flexural performance of fixed hollow steel beam.The discount in flexural performance of beam end openings was greater than that of mid-span openings.The characteristic end distance is about 2.5 times the height of the beam,and when it is smaller than this length,the opening has a greater discount on the load carrying capacity and stiffness,but when it is larger than this length,the increase of the end distance has a significant improvement on the load carrying capacity and stiffness.When the openings are all loacted in the mid-span,the flexural performance of hollow steel beams is close to that of solid-web beams.3.Increasing the hole height or length will decrease the flexural performance of the fixed hollow steel beam,and the degree of reduction increases with the increase of the hole height or length.The distribution of openings was an important factor affecting the flexural performance of fixed hollow steel beams.When the opening rate was the same,the uniform opening can increase the stiffness and load capacity of the member by about one time compared with the individual concentrated opening.4.In order to study the effect of hole height ratio and hole length-height ratio on the ultimate bearing capacity of open section,the calculation models of different hole length-height ratio and hole height ratio were established.By comparing the theoretical formula and the finite element results,the applicability of the theoretical formula of pure bending resistance was verified,and the theoretical formula of pure shear resistance was modified.Based on the calculated data,the bending-shear bearing capacity correlation curve equation was fitted.The above research content elaborated the influence of different opening parameters on the bending performance of fixed hollow steel beams and provided certain reference for future engineering applications of hollow steel beams.