Dynamic Effect of Rupture of Cable in Plane Prestressed Braced Steel Moment Frame

摘要

To study the dynamic effect of the prestressed braced steel moment frame caused by the sudden loss of a cable bracing, the instantaneous loading method is adopted to calculate the dynamic response of the remaining structure during and after the rupture of the cable with the simplified theoretical model as well as the finite element model. The results show that when the structure remains in the linear elastic state during the whole vibration process, the dynamic response is only related to the failure time of the broken cable and the damping ratio of the remaining structure. The maximum value of the dynamic factor approaches to 2.0. Moreover, the dynamic factor decreases when the failure time or the damping ratio increasing; but when the structure yields and enters the plastic state during the vibration, the dynamic response is also related to the demand-capacity ratio and increases with the increase of this ratio until dynamic divergence happens. The unloading impact from the broken cable is alleviated by the unbroken tensile cable, which makes the steel frame not easy to enter the plastic state.