Elastic-to-Plastic Strut-and-Tie Model for Deep Beams

The strut-and-tie model (STM) has been adopted as a preferred methodology for the design of disturbed regions of structural concrete; however, the service behavior of structural concrete, especially with regard to cracking, cannot be predicted well by a STM, which is based on the lower-bound theorem of plasticity. To address this issue, this paper presents the development of an advanced elastic-to-plastic STM (EPSTM) to capture the full elastic and inelastic responses of a deep beam. The principle of stationary complementary energy was introduced into the STM to satisfy the compatibility and generate the adaptive EPSTM at each load step. The proposed EPSTM provides a consistent analysis of the behavior of a deep beam, including the average strain of struts and ties, load-deformation response, and the maximum crack width. Through comparisons of model outputs with test results, the proposed model was verified to be sufficiently accurate.