Numerical modeling of reinforced concrete wall-floor joints

Current practice of the design of precast reinforced concrete joint is based on empirical relationships that often do not reflect the complexity of real geometric configuration. However, recent developments in numerical modeling of reinforced concrete structures now allow for realistic and accurate description of the failure mechanism, produced by extreme loading conditions. In this study a numerical model of different joint failure mechanisms in precast concrete structures is presented in detail. Presently developed methods, in building analysis are used to simulate the behavior of such joints under the influence of vertical and lateral loads. The type of joints considered in this study consists of reinforced interior or exterior wall-to-floor connections with either reinforced or unreinforced grout filler material.;In the implementation of the nonlinear finite element analysis, multiaxial stress strain laws are used to describe fracture phenomena with proper allowance for complex loading and unloading cycles. A rotating crack model is used to reach the needed accuracy to numerically describe fracturing of the reinforced concrete medium. In this model, it is assumed that the crack follows the principal strain direction and, therefore, varies with time. An iterative approach is used to solve the nonlinear problem.;Numerical results are obtained for a model that includes a portion of the slab on one side of the exterior joint and on both sides of the interior joint being analyzed as well as part of the wall above and below the slab. The model is assumed to be two dimensional corresponding to a plane strain condition. Solutions obtained by means of a nonlinear finite element program yielded detailed information for the behavior of the connection under severe loading conditions. The numerical solution includes the generation of stress contours in the connection and the graphical representation of the crack patterns. The program output is compared with the analysis based on the provision of the ACI Code.;This study clearly demonstrates the need of using the numerical model for the analysis and design of precast reinforced concrete joints.