Web-post buckling of bolted castellated steel beam with octagonal web openings

This paper presented numerical investigations on the behavior of a Bolted Castellated Steel Beam (BCSB) with octagonal web openings. Instead of welding the upper and the lower Tee-sections of a Castellated Steel Beam (CSB) together in the factory, they were connected using high strength bolts at the construction site. Thus, the upper and the lower Tee-sections can be transported separately, especially being convenient for a castellated steel beam with great section height. The residual stresses in the web-post induced by welding could also be avoided. The shear buckling behavior of the web-post in a BCSB with octagonal openings was studied using a verified finite element model. The buckling mode and the buckling strength of the web-post in a BCSB were compared with those of a traditional Welded Castellated Steel Beam (WCSB). Research results showed that web-posts in a BCSB with octagonal web openings had as good structural performance as those in a WCSB. Studied parameters of the BCSB included the bolt diameter, the width-to-thickness ratio of the web-post and the bolt layout. To increase the buckling strength of the web-post, a BCSB using stiffened connection plate was proposed. The Strut Model for predicting the buckling strength of the web-post in a traditional WCSB was employed for calculating that in a BCSB. Comparisons of buckling strengths obtained by Strut Model predictions and finite element simulations showed that the Strut Model could be used to predict the web-post buckling strength of a BCSB. •Web-post buckling behavior of Bolted Castellated Steel Beam (BCSB) was investigated.•The web-post of a BCSB would have three failure modes.•Strut Model was modified to predicate web-post buckling strength of BCSB.