Fatigue Analysis Method through Load Spectrum Considering Cyclic Characteristics for Highway Bridges
To consider the analysis accuracy and practicability of fatigue load spectrums,this paper proposed the proportional coefficient of damage effects and the cyclic characteristic lengths corresponding to single-vehicle loading and multi-vehicle loading.Through the investigation of general fatigue damage effects of typical fatigue vehicles,it constructed a damage analysis method of fatigue load spectrum from single-vehicle loading to multi-vehicle loading for load spectrum.The results show that the fatigue damage caused by a single fatigue vehicle can be scaled based on the concentrated load effects,and the cyclic characteristic length converted from the absolute area of influence lines has good applicability for the fatigue analysis of single-vehicle loading.The fatigue damage caused by random traffic flow is affected by both the bridge span and traffic flow density.In short-span bridges,the damage effect is not sensitive to traffic flow density,and the increase in traffic flow density may even lead to a decrease in the force amplitude in some cases.When the bridge span exceeds a certain critical value,traffic flow density shows a significantly increased influence,and the cyclic characteristic length converted from the integral area of influence lines is more suitable for the effect analysis of fatigue damage of traffic flow.The equivalent stress amplitude of the load spectrum shall be analyzed in combination with the traffic flow state spectrum,and the effects of vehicle encounter probability and cyclic characteristic length shall be considered for the formulation of multi-lane damage effect factors.
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