Linear and Geometric Nonlinear Effect of Axial Load on Flexural Deformation of Reinforced Concrete Members

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


The problem of a concrete cross section under flexural and axial loading is indeterminate due to the existence of more unknowns than equations. Therefore proper analysis of reinforced concrete member is important for understanding the actual behavior and economical use of sections. The main objective of this Thesis is to investigate geometric nonlinear effect of axial load on flexural deformation of reinforced concrete members. Flexural members, which are subjected to gravity central point load, external compressive axial load and combination of those load with different support conditions, cross section and span length are analysed using linear and geometric nonlinear method of analysis to investigate the effect of axial load on flexural deformation of flexural members. The percentage variation of flexural deformation under linear and geometric nonlinear analysis for various conditions of members is calculated to achieve the objective. Finally four story reinforced concrete residential building frame is analysed using linear and geometric nonlinear analysis. Both linear and geometric nonlinear analysis is done by using STAAD Pro and linear analysis using FEM based code using Scilab and ETABS. After the analysis of flexural members it is found that: The percentage variation of linear and geometrical nonlinear deflection is very high for beam with lesser depth. It was found that the support conditions also affect variation of deflection for the linear and nonlinear cases. The variation between linear and geometrical nonlinear deflection of beam is negligible when the ends are fixed. But for the same beam with simply supported end conditions the defections were found having variation up to 17.571 percentages. Geometrical nonlinearity is more when the load is very high and lesser depth. At the initial stages of loading behavior of beam is linear only and it behaves nonlinear when we go for higher loads. As the deforming of middle plane (Neutral axis) starts, the stiffness of structure increases (axial stiffness is added with bending stiffness).Thus the beam becomes stiffer progressively. It is a positive aspect of geometric nonlinearity.



Nonlinear Analysis, Finite Element Method, Flexural Deformation, Reinforced Concrete Beam, STAAD.Pro, Scilab.code