Model updating of an existing bridge with high-dimensional variables using modified particle swarm optimization and ambient excitation data

•A model updating approach for structures with high dimensional variables was proposed.•The new approach improves the searching and convergence ability.•Performance of the modified particle swarm optimization was illustrated by numerical functions.•Performance of proposed method is better than GA through beam example with 10 variables.•Application of proposed method to an existing bridge with 13 variables was successful.