SECOND ORDER EFFECT ANALYSIS OF REINFORCED CONCRETE FRAMES BASED ON ANALYTICAL STIFFNESS MODEL

The load capacity of reinforced concrete frames is investigated considering the material and geometrical nonlinear characteristics. An analytical stiffness model for reinforced concrete frames is presented based on the equivalent curvature formula derived from Eurocode. The tension stiffening of concrete is taken into account within the analytical stiffness model. Based on the deformation compatibility condition, the deflection equations are derived considering the P-Δ effect and P-δ effect. The moment redistribution in the frame is achieved based on the proposed analytical stiffness model and the deflection equations. Comparison with test data illustrates that the proposed load capacity evaluation method is feasible and the bending moment and lateral deflection of the frames increase nonlinearly with the increase of the bearing load.