HSB460 강재를 적용한 조밀 강합성 I-거더 단면의 연성비를 고려한 부모멘트부 공칭휨강도

Abstract

This paper presents a new nominal flexural resistance of compact composite I-girders sections using HSB460 steel under negative bending. In the 2014 AASHTO LRFD bridge design specification, the nominal flexural resistance of the compact composite sections under negative bending does not take into account the ductility ratio which may be defined by the distance from the plastic neutral axis to the extreme fiber of a bottom flange over the total depth of the composite section. The objective of this paper is to propose a new the nominal negative flexural resistance with considering the ductility ratio. An extensive parametric study for a wide range of cross sections was performed with the ultimate negative flexural strength obtained by using the strain compatibility method. The full plastic moment, the ductility ratio, and the width to thickness ratio of a compression flange were calculated according to the AASHTO specifications. From the results of the parametric study, the new width to thickness ratio limit value varying with the ductility ratio was suggested for assuring that the ultimate flexural strength can reach the full plastic moment. In addition, the new nominal negative flexural resistance incorporating this limit was proposed.