Behaviour and analysis of reinforced concrete walls subjected to reversed cyclic loading.

摘要

Details of two large-scale wide-flanged structural walls, tested under cyclic displacements, are presented. Results indicate that axial loads, although relatively small, and adjoining flange walls had a significant effect on the strength, ductility, and failure mode of the test specimens. The behaviour of the walls was dominated by shear related mechanisms, and as a consequence, the web elements sustained heavy damage. Secondary effects are examined and discussed, and include the in-plane horizontal expansion of the web wall and the elongation of the flange walls, which affect the failure load and failure mechanisms of structural walls. Such data is useful in understanding behaviour and corroborating analyses.; The series of wall tests conducted will complement the literature with data on structural walls in which the response is dominated by shear mechanisms, and with data involving complex wall configurations in which three-dimensional effects may be influential. Currently, the literature is lacking in these areas.; Formulations are presented for concrete subjected to cyclic loading in the compression and tension regimes. The proposed models were implemented into a two-dimensional nonlinear finite element program, applicable to reinforced concrete membrane structures. The algorithm is based on a secant stress formulation employing the smeared rotating crack concept. This analytical work is one of the first to implement formulations for cyclic load analysis based on the rotating crack model. Enhancements in the modeling include nonlinear unloading, degradation in the reloading stiffness based on the amount of strain recovered during unloading, improved plastic offset formulations, and partial unloading/reloading rules.; Analyses of structural walls currently available in the literature, and those tested as part of this research, demonstrate that the proposed concrete cyclic models provide reasonably accurate simulations of behaviour, indicating that the Modified Compression Field Theory formulations can be adapted for general load history analysis using a secant stiffness formulation. Further analyses of reinforced concrete shear panels have identified areas of the concrete modeling requiring improvements.