Research On Anchorage Properties And Wind-induced Vibration Of Long Span Cable-stayed Bridge With CFRP

The cable-stayed bridge is widely used in long-span bridges because of its beautiful appearance, strong spanning ability and high rigidity while the cables are important components of cable-stayed bridges.Due to ultimate strength, low bearing efficiency and weak corrosion resistance of traditional steel cables, the span of cable-stayed bridges can not be improved greatly. CFRP (Carbon Fiber Reinforced Polymer) has many excellent features such as non-corrosion, non-magnetism, low relaxation, lightweight property, high strength, strong fatigue resistance and so on. It can be applied in the cables of prestressed long-span stay bridges. Consequently the CFRP has wide application prospects in the long-span bridges. However, the anchorage of CFRP cables has yet to be resolved because of the anisotropy of the material before wide replacement of CFRP cables with steel cables. In addition, brittle and lightweight CFRP cables with low modulus of elasticity are vulnerable to wind or rain-wind vibration or in the other harsh environment. This thesis tends to design the reasonable anchoring system of CFRP cables and explore the nature of the wind-induced vibration based on the National Natural Science Fund Project-"Research of long-span bridge prototyping and related issues with high performance materials CFRP cable (No.51078170)". Relevant work as follows:(1) Theoretical and experimental research was carried out on the anchorage system of CFRP cables.The applicability of various types of anchorage systems was researched. Theoretical calculation models were established and verified by experiments. Design suggestions for CFRP tendon (cable) anchors with large tonnage were proposed by optimization analysis.(2) The characteristics of the wind-induced vibration of CFRP cables compared to steel cables were studied based on the fluid-solid coupling theory.The analysis method of structural responses of CFRP cables was proposed based fluid-solid coupling theory. The performance and the characteristics of the transient kinetic responses of CFRP cables were deduced under strong wind loads in various cases. The difference between CFRP cables and the steel cables in structural responses was compared under the same cases.(3)Wind-rain induced vibration characteristic of CFRP cables was researched based on the quasi-steady assumption.The simplified model and stability criteria of wind-rain induced vibration towards CFRP cables were suggested. The characteristics and influence of parameters on wind-rain induced vibration of CFRP cables were analyzed. Response rules, mechanism and parameter sensitivity of CFRP cables were analyzed based on the simplified model of wind-rain induced vibration.To sum up, the anchorage system has been optimized towards CFRP tendons/cables and the design advises have been proposed for the anchorage with large-tonnage for CFRP cables in this thesis. Simplified model of structural responses of CFRP cables under wind was deduced based on fluid-solid coupling theory and then the transient properties of wind-induced vibration and rules with different parameters of CFRP cable have been obtained which were quite different from that of steel cables. The results could be some references for the design and application in long-span bridges with CFRP cables.