Strut-and-Tie Model-Based Prestress Design for the Cable–Pylon Anchorage Zone of Cable-Stayed Bridges

Due to its complex geometry and mechanical behavior, the prestress design of the cable–pylon anchorage zone is difficult to achieve but critical. In this paper, the use of the strut-and-tie model (STM) is evaluated to simplify the cable–pylon anchorage zone design. The traditional Evolutionary Structural Optimization (ESO) method is first used to generate the STM of a common one-box two-cell cable–pylon anchorage zone. However, the resulting STM is shown to be irrational by comparison with the real distribution of principal stress in the cable–pylon anchorage zone. Therefore, this paper proposes a tailored ESO method using a modified algorithm for the removal criterion based on the strain energy of the element. The proposed method is shown to overcome the drawback of the classical ESO method that some elements playing key roles in the distribution of principal stress, but having small von Mises stresses, may be deleted mistakenly. The prestress design of the Cao’e River Bridge is then presented using the correct STM generated by the tailored ESO method as a practical example. Finally, the rationality of the resulting prestress design of the cable–pylon anchorage zone is substantiated using the results of a full-scale model test.