Restrained distortional buckling and postbuckling behavior of steel-concrete composite beams under hogging bending

摘要

This paper deals with the behavior of castellated composite beams. Web posts and the bottomrnflange of castellated composite beams in the hogging bending regions demonstrate much weaker behaviorrnagainst restrained distortional buckling (RDB) if compared with plain webbed beams. Less attention has beenrnpaid in research to out-of-plane buckling of castellated composite beams, especially with reference to the effectsrnof hogging bending region length and shape of openings. The paper summarizes the program of experimentalrninvestigations and numerical modeling of the behavior of steel-concrete castellated composite beams of differentrnopening shapes under hogging bending. Research has been conducted at theWarsaw University of Technology.rnTwelve composite beam specimens were tested and examined numerically, namely six long span beams in whichrnflexure controlled the behavior and six short span beams in which the effect of shear could not have beenrnneglected. Experimental setup allowed for detailed monitoring of the load-deflection behavior, evaluation of thernbuckling strength, identification of the failure modes and finally allowed for tracing the postbuckling behaviorrnrepresented by a descending branch of the beam load-deflection characteristic.An analytical proposal is verifiedrnfor the prediction of the RDB strength on the basis of results of conducted experimental work.