An online optimization method for bridge dynamic hybrid simulations

An online optimization method was proposed in this paper to improve the accuracy of numerical–experimental hybrid simulations of bridges subjected to earthquake forces. The online optimization method aims to solve the problem induced by the inconsistency of the multiple identical bridge piers where only one or a few of them are simulated experimentally by physical specimens, while the others are numerically simulated within a hybrid framework. This method adopts multi-variable nonlinear optimization in order to find the optimal material parameters of the numerical models, and updates the numerical models instantaneously during the hybrid simulation. A numerical verification of a bridge hybrid simulation was conducted using the proposed online optimization method. The numerical results showed that the online optimization method is capable of obtaining better material parameters during the first few seconds of a hybrid simulation, which results in more accurate nonlinear dynamic response under earthquake loading.