The effect of eccentricity at beam support to beam stiffness

Abstract

A beam reacts to loading through bending action. Therefore, beam bending stiffness can be represented by deflection. Theoretically, beam stiffness is governed by span length, elastic modulus, moment of inertia and support type. In the analytical analysis, beams are assumed simply supported or fixed supported. However, based on real cases and lab experiments there are other factors that are not included theoretical equation but effect to the beam stiffness. Factors such as eccentricity between beam neutral axis and beam support (vertical eccentricity), pour stop stiffness in composite beam/slab effect and column size effect were analyzed in this study. The effects were studied using plane stress element finite. Pour stop stiffness were modelled using spring element. From the analysis, vertical eccentricity does not give significant effect to beam stiffness and it can be neglected. The pour stop provides stiffness of 25000kN/m at the outer support. Beam deflection is independent with column deflection when column width is three times bigger than beam depth.