Experiment and parameter analysis of pin-loaded CFRP strap suspenders for suspension bridge
[Objective]As critical load-bearing members in suspension bridges,traditional bridge suspenders are usually made of steel.However,steel suspenders are subjected to corrosion,creep and other issues,causing premature failures of the suspender system and additional maintenance costs of the bridge.Carbon fiber reinforced polymer(CFRP)materials exhibit high strength-to-weight ratio,corrosion resistance,fatigue resistance,ease of installation and reduced maintenance costs.Hence,they have become a potential substitute for steel materials.In bridge suspenders,CFRP materials are mostly shaped into the form of rods,and this formation leads to the problem of anchoring.Also,the unidirectional arrangement of fibers weakens the transverse shear resistance of the cable,thus further complicating the solution of CFRP-cable anchoring problems.[Methods]In this paper,a pin-loaded CFRP strap suspender was proposed.In this strap suspender,CFRP prepregs with continuous unidirectional fibers were wound by layers around two pins,which facilitated the load transfer.Static tensile experiments were performed to investigate the load-bearing capacity and failure mode of pin-loaded CFRP straps.Through the finite-ele ment analysis software ANSYS,a finite-element model was developed,and parametric analyses were performed on strap layers,wedge angle,and friction coefficient.Based on these experimental and parametric-analysis results,a whole bridge model was established,with an example of the Wufengshan Bridge.[Results]CFRP strap was made of unidirectional fiber wound by layers,and thus indured weak interlaminar shear strength.In the static tensile experiments,with the increase of load,the strap appeared delamination at the intersection of straight lines,accompanied by the emergence of transverse cracks.With the delamination and transverse cracks propagated to the curved segment and straight segment,brittle fracture occurred in the strap at the intersection of straight lines.The scanning electron microscope(SEM)images showed that the fiber fracture occurred at the fracture position of the strap,and the brittle failure of the strap also appeared.As the wedge angle increased,the ultimate load of the strap gradually decreased.At the wedge angle of 27°,the average fracture stress of the strap could reach 80％of that of the straight strap.Satisfactorily,numerical results agreed with the experimental counterpart.It was shown that,with the change of strap layers,wedge angles and friction coefficient,the stress at different positions of each layer of the strap changed to different degrees.The stress and strain distribution of the curve segment and its adjacent straight segment were severely affected by the change of parameters.This situation greatly influenced the load-bearing capacity of the strap.Before and after the replacement of CFRP suspenders in the whole bridge model,the bridge changed insignificantly in static and dynamic characteristics.This outcome demonstrated the feasibility of CFRP strap suspenders for the whole bridge.[Conclusion]The pin-loaded CFRP strap suspender is proposed in this paper,and satisfactory mechanical properties are observed.After the whole bridge replacement in numerical analysis,the pin-loaded CFRP strap suspender shows the feasibility in whole bridge application,and effectively solves the problem of poor anchorage performance of traditional CFRP suspenders.Reducing the wedge angle of the drop-shaded component and the friction coefficient of the contact surface,we effectively improve the load-bearing capacity of the CFRP strap suspender.Hopefully,our parametric analyses can offer suggestions for the application of the pin-loaded CFRP strap suspender in practical engineering.
composite materialsCFRP strapnumerical simulationparameter analysiswhole bridge model
万方数据
维普
