Abstract
In order to withstand the greatest likely earthquake, building frames without shear walls should have adequate ductility, which is defined as energy dissipating capacity and bearing capacity to lateral load after reversals. It has been pointed out by many experimental studies that bond failure either in member or in beam-column joint degrades much of ductility of structural frame. The objective of this study is to propose a relatively simple methcod of frame analysis considering bond-slip characteristics. This method is essentially one dimensional. Uniaxial constitutive models of steel, concrete, and bond are utilized. Steel and bond were assumed to be linerly elastic in this paper. Equilibrium between bond stress and steel stress is satisfied all along the main bars, passing through the members and joints. Equilibrium between inner forces of a member (moments and axial forces) and the axial stress in a section is satisfied only at both ends of the member. Degrees of freedom of a member are limited as eight, which are (1) rotation and axial deformation at both ends of the member (4DOF), and (2) pull-out (or push-in) of top and bottom bars from adjoining joints (4DOF). The concrete in a beam-column joint is assumed as rigid (shear deformation is ignored), and only the axial strain and slip of main bars are assumed to occur in the joint. The anti-symmetrically loaded beams were analyzed, where the parameters were (1) bond-slip stiffness, and (2) with or without pull-out of main bars from adjoining joints. Analytical results were compared with experimental results.
