Experimental Research on Mechanical Property of Sliding Steel Anchor Boxes Used to Anchor Stay Cables in Pylons
In the Fulong Xijiang River Bridge in Foshan,the stay cables No.4-No.26 are anchored in the pylons via a type of sliding steel anchor boxes.A 1∶2 scale model was prepared to test multiple issues related to the mechanical properties of the new type cable-pylon anchorage structure,including the working performance of sliding sets,stresses in steel anchor boxes and concrete pylon columns,the vertical relative sliding between steel anchor boxes and concrete pylons,force transfer paths of stay cables and propagation of cracks in concrete walls.The results show that the friction coefficient of the sliding set formed of stainless-steel concave and two-component graphene-modified fluorocarbon anticorrosive coating is 0.055,suitable for the sliding steel anchor box.Under the action of stay cable forces,the lateral tensile plate in the steel anchor box endures the interaction of tensile,bending and shear stresses,with the maximum stress reaching 150 MPa,relatively low.The maximum tensile stress in the concrete pylon columns along the bridge length is 0.57 MPa,indicating that there is no potential cracking risk even without prestress.The relative vertical sliding between the steel anchor box and concrete pylon columns is slight,proving that there exists a reliable connection between the two,and the two can carry vertical cable forces together.Before the locking of the sliding end,nearly all the vertical forces are transferred to the concrete pylon columns via the shear connectors at the fixed end of the steel anchor box,and roughly all the horizontal forces are carried by the steel anchor box.After the locking of the sliding end,the stay cable force increments are shared by the steel anchor box and concrete pylon column.When loaded to 2.5 times of the standard combination of stay cable forces,vertical and horizontal cracks gradually appeared in the structure,but the widths of all the cracks are small,with a maximum crack width of merely 0.2 mm.
cable-stayed bridgecomposite cable-pylon anchorage structuresliding setsliding steel anchor boxconcrete pylon columncable force transfer pathcrackmodel test
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