Finite element analysis of deep beams on nonlinear elastic foundations

This research deals with the nonlinear material and geometric behaviors of reinforced concrete deep beams resting on linear or nonlinear Winkler foundation. The finite elements through ANSYS (Release-11, 2007) computer software are used. The reinforced concrete deep beam is modeled using (SOLID 65) 8 node brick element and the soil is modeled using linear spring (COMBIN 14) element or nonlinear spring (COMBIN39) element. The results obtained from the present study are compared with available analytical or experimental results. Good agreement is obtained with available results which also indicate the efficiency of the finite element method used to model the problem. The difference in maximum deflection between large and small deflections theory is found to be small. The maximum stress is increased when the beam is resting on nonlinear Winkler foundation because of reduced foundation stiffness. Several important parameters are incorporated in the analysis - namely the vertical subgrade reaction, mesh size, and compressive strength of concrete - to study their effects on the beam behavior. The results demonstrate that the difference in maximum deflection between the linear and nonlinear model of soil is about (2.5%).