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. (C) 2018 American Society of Civil Engineers.