Experimental study on the flexural performance of a continuous beam with variable section corrugated steel webs

To examine the flexural performance of a continuous composite box girder with variable-section corrugated steel webs, the hydraulic servo system is used by the way of step loading, static failure tests were performed on a continuous model girder with three-span corrugated steel webs, obtaining the failure modes and deformation, strain distribution on different sections, increment of external prestressing tendons, and ultimate bearing capacity of the continuous box girder with corrugated steel webs under symmetrical and eccentric loads. Accordingly, the failure process of the continuous composite box girder with corrugated steel webs was clarified. Research results show the following: In the elastic range, the longitudinal strain of the concrete top and bottom of the side span and middle span linearly varies, which is in accordance with the "dummy horizontal section assumption" proposed in beam theory. The eccentricity effect at the side span is larger than that at the middle span under a partial load, which is related not only to the shorter side span but also to the number and location of the diaphragm. The cracking load of the box girder is 30% of the failure load, and the variation rate of the deflection of the middle span and side span increases after the cracking of the bottom concrete. The strain of the concrete top and bottom of the side span in the middle suddenly changes after the cracking of the middle bearing. Then, the growth rate increases, and it continues until the end of loading. In the final failure moment, oblique cracks and fractures occurred on the concrete top and bottom plate at the mid-span loading point, and a buckling failure occurred on the steel web. The prestressing tendons bear high stress in the failure stage and greatly contribute to the flexural performance of the continuous composite model beam. The experimental results can provide some reference for the engineering application of continuous composite box girders with corrugated steel webs. © 2023 Editorial Board of Journal of Harbin Engineering. All rights reserved.