Research On Key Technologies Of Multi-span Extradosed Cable-stayed Bridge

Extradosed cable-stayed bridge is a new bridge type which is between rigid beambridge and flexible cable-stayed bridge and has the characteristics of both of them.Multi-span extradosed cable-stayed bridge is more and more used in large span bridgefor its structure characteristics as well as advantages of economical and landscapecoordination. Multi-span extradosed cable-stayed bridge is a complex structure withhigh order statically indeterminate. Key construction technology has direct influenceon its forced state and service performance. One can study out the closure jackingforce and cautions of closuring by calculation and analysis. Tension of stayed cablehas a significant effect on forced state and linear control of multi-cable extradosedcable-stayed bridge. To find an optimization scheme of tensioning is meaningful forcontrolling the cable tension of parallel strand. This paper use the West River Bridgeas project background to research some details as follows whit MIDAS model:(1)Introduce the origin, definite Standards and the development situation,structure characteristics of extradosed cable-stayed bridge briefly.(2)Study out optimal closure jacking force by taking horizontal displacement oftower top and piers stress10years after bridge completed as optimized object. Andthe force is to be corrected considering the closure temperature influence.(3)Find out that there is a displacement asynchronous problem in the closureprocess by analog computation. And solve the problem by using unbalance weights.At last the closure jacking force is proofed that it is safe and effective.(4)Summarize the influence law of forced state by analyzing the parametersensitivity of cable force and comparing it with internally prestressing.(5)The reason and solution of cable tension error are discussed. The cabletension error of stay cable and the discretization error of steel strand are analyzedquantitatively. At last the optimization scheme of tensioning is presented. The resultsof analog calculation show that the scheme is a practical way to control the cabletension of parallel strand.