Optimization of Steel Liner on Spiral Case Structure for a Large Hydropower Station

Abstract

Traditionally, spiral case structure is classified as non-member bar reinforced concrete structure. It is improper to calculate reinforcement area according to the area of tensile stress figure, which often causes a lot of waste of reinforcement; it is particularly true for the spiral case structure with steel liner. In combination with the practice of a spiral case of the hydropower station, the different schemes are proposed by 3-D nonlinear FEM software ABAQUS to study the feasibility of thinning steel liner in this paper. It is indicated that magnitude of steel liner and the hoop reinforcement stress is of no obviously increasement, damaged region of concrete is of no significant variation and the cracking range of peripheral concrete is of the requirements when the rate of steel liner thinning is tiny. When the thinning rate is 10%, there is a significant increase in crack width, but it still can meet the requirements of the specification. Although the magnitude of the stresses is not beyond the strength requirement, the maximum cracking width of concrete is over the designed standards when the rate is up to 30%. In this case, the crack width is controlled by collocating the more reinforcement in local positions. It is concluded that steel liner thinning is reasonable and feasible; what’s more, the magnitude of thinning is very large when the more reinforcement are collocated without prejudice to construction. It can provide references for optimization of the steel liner for the similar projects.