| As an important element of the cable-stayed bridge structure,the stay cable connects the main tower to the main girder and plays a key role in transmitting the load from the main girder to the main tower and ultimately bearing the foundation load.As the span、design life and component load levels of cable-stayed bridges and buildings increase,higher demands are placed on the performance and life of the key cable members.Improving the strength and fatigue stress amplitude of cold-cast anchor stay cable is of great importance in the design and construction of oversized span bridges.This paper therefore investigates the structure of cold-cast anchor parallel wire stay cable,the performance of the cold-cast filler,and the structure of the inner wall of the anchor cup.The paper also investigates the corrosion problem in the lower anchorage area and proposes a flexible double sealing structure to improve the sealing and waterproofing capability of the stay cable.The main research contents and conclusions are as follows:(1)The anchoring principle and anchoring structure of the cold-cast anchor stay cable were analyzed,and the stress concentration of the stay cable at the anchor cup was obtained by using the mathematical derivation formula of the radial stress distribution of the anchorage in the axial direction(notch effect)s reason.In order to reduce the stress concentration of the stay cable in the anchor section,the filling method of the chilled casting filler and the inner cavity structure of the anchor cup can be optimized.(2)The performance of the cold-cast filler was studied,and a high-strength,high fatigue stress amplitude cold-cast anchor for steel wire stay cables was proposed based on the variable stiffness cold-cast filler and wedge-shaped anchor cup structure.The reliability of the cold-cast anchor for improving the strength of the strong steel wire stay cable was verified by fatigue and static load tests of LZM7-37 and LZM7-379 with a strength of 2100 MPa and fatigue stress amplitude of 280 Mpa.In the LZM7-187 static load stress test,it was demonstrated that the cold-cast anchorage optimized the stress distribution of the wire in the internal segment of the anchor cup by layering the cold-cast filler with different elastic molds,by transferring the stresses of the wire at different locations collected by the wire smart tendons of the test fiber.(3)Based on the finite element analysis method,the simulation research on the cold cast anchorage of the stay cable is carried out.The LZM7-37 finite element model is established,and the tensile simulation of the 2100 MPa breaking force is carried out on the LZM7-37 finite element model.The simulation results show that the high-strength chilled cast anchorage design can achieve effective anchorage to steel wires.The influence of different rigidity cold-cast fillers on the force of the anchor wire and the influence of the inner cavity structure of the anchor cup on the stress distribution of the wire are also studied by finite element simulation.The finite element simulation results show that various chill casting filling methods with variable stiffness can reduce the maximum stress of the anchor cup and steel wire;the wedge-shaped multi-level anchor cup and the arc-shaped anchor cup can effectively improve the stress distribution of the anchor.(4)The sealing and waterproof structure of the anchorage area under the stay cable was studied,and a double flexible sealing and waterproof structure of embedded pipe was proposed based on the surface transition membrane.The dynamic watertightness test and the static watertightness test prove that the double flexible sealing waterproof structure of the embedded pipe has excellent sealing performance. |
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