The article investigates how cable-stayed girder bridges behave when they vibrate freely or when a moving load passes over them. The researchers calculated how much the bridge bends and the bending force it experiences when a vehicle goes over it. They compared their calculations with real tests on the Toyosato Bridge. The stiffness of the cables affects how the bridge vibrates, and the speed of a vehicle affects the forces on the bridge. The researchers also looked at how well Japanese bridge design standards account for these dynamic forces.