Study On The Influence Of Cable Damage On The Mechanical Properties Of Ⅴ-type Double Arch Cable-stayed Bridge

Ⅴ-shaped double steel arch tower cable-stayed bridge has been widely recognized in urban bridges for its advantages of beautiful shape and large span.Like the conventional cable-stayed bridge,the cable,as the main load-bearing component of this kind of bridge,is directly arranged outside the main beam and the cable tower.Vehicle impact,fatigue and corrosion may cause serious damage to the cable.In addition,in extreme cases such as fire and storm,the cable is easy to break,which then threaten the safety of the bridge,but the current research on the damage and fracture of the cable of this kind of bridge is very limited.In order to ensure the safety of this kind of bridge during operation,it is necessary to study the influence of cable damage on the mechanical properties of this kind of bridge.In this paper,taking Fenghe bridge of Fuyu road in Xi’an as an example,the finite element model of the bridge is established to analyze the change rule of mechanical properties of the bridge under different cable damage conditions.The specific research contents and main results are as follows:(1)Taking Fenghe bridge of Fuyu road in Xi’an city as the research object,according to the as built drawings,construction monitoring data and the later detection data of the bridge,Midas/Civil was used to establish the three-dimensional finite element model of the bridge.The main beam,tower displacement and cable force during the construction of the bridge are analyzed,and the rationality of the model is verified by comparing with the design value and code of the bridge.(2)Using Midas/Civil software’s passivation function to simulate the cable’s fracture,and reducing the cross-sectional area of the cable to simulate the cable’s different degree of damage.It is considered that the number and location of the broken cable have obvious differences on the main beam’s line shape and the residual cable force,and the cable force and displacement monitoring strategy of this kind of bridge is given.(3)Based on the analysis of the stress changes of the main girder and pylon under different cable breaking conditions,it is considered that the influence of cable breaking on the residual cable force is higher than that on the pylon and main girder;The influence of different cable breaking areas on the dynamic characteristics of the structure is also different,and the influence of multiple cables breaking at the same time on the natural vibration characteristics of the structure is superimposed;Considering the earthquake action,the maximum deflection span ratio of the main girder is 1/601,the maximum stress of the cable is 890 MPa,and the safety factor of the cable is 2.08;The effect of vertical seismic action on the remaining cable force is higher than that of horizontal seismic action.