Effect of Partial Fixity on Negative Bending Moments in RCC Frames

Abstract

This paper presents the variation of bending moments in the RCC frames structure for different ratios of moment of inertia of the column and the beam (IC/IB). In this study, three different cases of frames structure are considered e.g. the first case is single bay single storey to single bay five storied frames structure, the second case is two bays single storey to two bays five storied frames structure and the third case is three bays single storey to three bays five storied frames structure. The investigation is mainly focused on the variation of negative moments at the beam ends at the first floor of ith storey frame structure with the variations of IC/IB ratio, number of stories and number of bays in the frames structure. STAAD Pro software is used to model and analyse the considered frames structure. The obtained results are presented in tabular form to observe the effects of IC/IB ratios at the joints in each floor of five storied frames structure. Results are also compared with the analytical one and found to be satisfactory. Few interesting results observed in the analysis of three different cases of frames structure are presented herein. Investigated results on RCC frames structure may be useful to the engineers and designers.

Keywords: Frames structure, stiffness method, rotation contribution method, negative bending moments, inertia ratio