Secondary bending moment in the design of beam with trapezoid web profile

Abstract

Secondary bending moment, Myf is particularly occurs to corrugated web or beam with trapezoid web profile (TWP) subjected to in-plane shear force which causing flange of TWP beams to bend in lateral direction. Therefore, flange will experience double axial bending (bending in major and minor axis). This research was to seek the relationship of secondary bending moment coefficient (Co) with the geometry of TWP beam i.e. web depth (d), web thickness (tw), corrugation depth (hr), the width of flat subpanel (b), and corrugation angle (a). To achieve this objective, an experimental work and also finite element have been conducted to clarify and to give clear understanding on Myf and also to compare results from experiment and finite element analysis (FEA). Based on result of lateral deformation comparison between flat plate and TWP, due to inclined panel of corrugated web, TWP beam possess secondary bending moment. In this study, analysis on the secondary bending moment was made only on finite element results. The experimental result was found unreliable. In conclusion, the geometrical properties of TWP give very significant effects on the secondary bending moment except for the web thickness. The increment of hr, and b were identified to increase the Co values while, the increment of d and a were proved to reduce the Co values of TWP. Furthermore, the analysis using TWP without flange in finite element was found to be more appropriate.