| With the development of China’s economy,new infrastructure has emerged in large numbers throughout the country,in which case the construction of high-speed railroad bridges has attracted much attention,among which steel-box tied arch-bridges are widely used in the construction of high-speed railway bridges due to their good stressing properties.According to statistics,80%-90% of steel structure damage is related to fatigue,so the fatigue characteristics of steel-box tied arch-bridges under the reciprocating action of trains should be further studied to ensure the safety of such bridges in operation and to clarify the focus of subsequent bridge maintenance.The technical route of this paper is to select a high-speed railroad steel-box tied arch-bridge as the research object,and to evaluate the fatigue characteristics of this bridge based on the numerical simulation method for fatigue calculation.The main research contents are as follows.(1)After establishing a finite element model of a high-speed railway steel-box tied arch-bridge and verifying its reliability,the bridge model is loaded with traffic,and the stress time curves of each stress-concentrated member are subsequently extracted and compared to obtain the parts of the bridge most prone to fatigue damage.(2)A local finite element model is established for the most fatigue-prone parts,and the internal force at the most unfavorable loading moment of the whole bridge model is extracted and applied to the local model for force analysis to obtain the fatigue hazard key points of the local model.(3)The fatigue time curves of the standard fatigue vehicle and the standard live load at the bridge stress concentrated members were compared to determine the best fatigue load for the verification.(4)For the fatigue hazard critical points of the local model,the fatigue life was calculated using finite element software,and the fatigue strength of the critical points was evaluated according to the code and metal fatigue theory,and the two fatigue evaluation results were compared.Based on the above research content,the arch foot and side boom arch rib are the dangerous parts prone to fatigue damage;the stress amplitude generated by the canonical live load is about 2-5 times of the standard fatigue car,so the canonical live load is safer to be used for fatigue verification;the fatigue life calculation and fatigue evaluation of the fatigue risk key points are in line with the infinite life use state;comparing the two fatigue evaluation results,the canonical fatigue allowable stress amplitude of this structure is about It is very conservative for steel-box tied arch-bridge,and it is suggested to further study to determine the reasonable limit value. |
