The strut-and-tie model and the finite element - good design companions

The strut-and-tie method (STM) can serve as a tool for a safe design of concrete structures or members. It aids to trace the flow of forces, appropriately lay-out the reinforcement, and safely predict the structure capacity. On the other hand, the linear elastic finite element can be utilized as an alternative in the development of the strut-and-tie models besides the load path method. In addition, the nonlinear finite element analysis assists in the optimization of the design results obtained from the STM. Hence, the two methods work well as companions in structural design. In order to demonstrate such understanding, different examples which include a deep beam with large opening and recess, continuous deep beams with and without openings, and beam ledges, have been utilized. In the STM solutions, the ACI 318-14 failure criteria have been adopted. In the nonlinear finite element analysis, material nonlinearity has been accounted for. The obtained solutions from the two methods, along with the experimental data of the selected examples of this study, revealed the reliability of the STM in obtaining a safe solution. Besides, the nonlinear finite element proved to be an efficient tool in obtaining an economic design.