Static Analysis And Fatigue Performance Study Of Steel Anchor Girders For Concrete Cable-Stayed Bridges

Cable-stayed bridges are widely used in bridge construction in China.The anchorage zone of the cable towers is an integral part of cable-stayed bridges,with various anchorage forms and complex force conditions.Therefore,it is necessary to evaluate the safety of the anchorage zone of the cable tower.In this paper,the force state and fatigue performance of the cable tower anchorage structure are studied from the point of view of the cable tower anchorage structure,and the main work and conclusions are as follows:(1)The development history of cable-stayed bridges and the current research status of cable tower anchorage structures are described.The steel anchor bea m anchorage structure is selected for further analysis.Some theoretical methods of fatigue research on steel structures are summarized,and the ideas and methods of static and fatigue analysis of steel anchor beam anchorage structures are introduced.(2)Midas Civil and Abaqus CAE were used to build the entire bridge model and the local model of the anchorage area of the cable tower,respectively,and FE-safe carried out the fatigue life assessment of the structure.The maximum cable force was extracted from the entire bridge model for the static analysis of the local model and the subsequent fatigue life assessment of the structure.The results show that the static analysis results are within the allowable bearing range of the material.(3)The different connection forms between the steel anchor beam and the steel bull leg have less influence on the structural stress distribution,and the stress concentration is easily generated at the bolt position.When using the Option C connection method,significant co mpressive stresses appear at the location of the cable holes under the applied temperature load condition;under the asymmetric cable force condition,the stresses in the end cross partition change significantly;under the broken cable condition,the stres ses on the broken cable side drop sharply,and the stresses on the unbroken cable side increase slightly.Changing the number and thickness of stiffening ribs,considering the material cost and structural safety,the number of stiffening ribs should be con trolled in 3-4 groups,and the thickness of stiffening ribs should be controlled between 25 mm and 35 mm.(4)According to the traffic volume level,the fatigue model I of our country specification was used for loading.It was calculated that the fatigue damage of the steel anchor beam was slight at the local traffic volume level,which fully satisfied the design requirements of the specification.The fatigue model Ⅲ was used to load the steel anchor beam structure with full load and overload.The results showed that the fatigue life of the bolts decreased exponentially with increasing load;fatigue damage appeared at the bolt hole location at 60% overload;fatigue damage appeared at the bottom connection area of the steel bull leg web at 80% overload.The overload seriously affects structural safety,and the fatigue damage monitoring of the steel anchor beam structure should be strengthened during operation.