FULL-RANGE HYSTERESIS ANALYSIS OF CONCRETE FRAME AND TRUSS STRUCTURES

The element stiffness matrices of concrete frame and truss structures are derived in this paper based on the principle of nonlinear finite element-Utilizing the method that M-N-φ relations of element are formed directly from physical properties of material, the influence of material nonlinearity, geometric nonlinearity, effect of N-Δ, local contact effect of cracked concrete section, effect of prestressing, slip of anchor bars as well as the loading and unloading tangent modulus of material are all taken into account in the element stiffness matrices. Imitative calculations of hysteresis behavior of two concrete portal-frame specimens under reversed cyclic loading are carried out by using the corre-sponding analysis program, and results are in good agreements with experimental results. This program is capable of full-range hysteresis analysis of concrete frame and truss structures including decending part, providing an accurate and practical method for studies on seismic behavior of this kind of structures.