Analyse On The Process Of Suspender’s Fracture And Research On The Safty Countermeasure

Suspenders，the main components of half through or through arch bridge, connectingthe arch rib and the deck, transfer the constant loads and live loads from the deck to thearch rib for the arch bridge’s spanning function. The failure of suspenders may causefloor system’landslide and local failure or structural failure of the arch rib. So it isinsured that the suspenders must be save during service life, and avoid disastrousaccident if the suspenders break. But the reacting force generated when suspenders breakis not considered in existing design code for arch bridge, and the internal force anddeformation of girders, which is restricted in the detailed rules and regulations of roadcable-stayed bridge when inclined cable break, is not yet restricted. Therefore, the authortaking Shenzhen North Station bridge as engineering background, starts with the changeof the bearing and deforming behavior of the bridge before and after the suspender’sfracture, study and discuss the dynamic magnification factor of suspenders failure, andthen makes contrast analysis on the application of a safty countermeasure called safetysuspender system on arch bridge.Firstly, the model of the North Station Bridge is established by MIDAS/Civilsoftware and ANSYS/LS-DYNA software separately. The FEM calculation results meetwell with the test results under static and dynamic load, which indicates that the finiteelement model can reflect the real project and provide the basis for the finite elementanalysis of the process of suspender’s fracture.Secondly, by means of ANSYS/LS-DYNA software, the process of the suspender’sfracture, considered both double short suspender and double long suspender workingconditions, is simulated. The FEM simulation results indicate that certainsuspender’stress may exceed allowable stress, the girder maybe destroy and the floorsystem may be collapse.Thirdly, the suspender’s fracture is analyzed with static computation method byusing MIDAS/Civil software. The value selection of the dynamic magnification factor isdetermined with the method of parameter analysis. The analysis results indicates that thevalue of the dynamic magnification factor is between1.5and1.7when the shortsuspender failure, and is between1.6and1.7when the long suspender failure.Finally，the safety suspender system is applied on the North Station Bridge, and thedifference of bridge’s mechanical behavior is analyzed by finite element method. The analysis results indicate that the safety suspender system, compared parallel doublesuspender system, can reduce adjacent suspender’s increscent axial force when thesuspender break, and therefore reduce the possibility of suspender’s continuous fracture.