The Research On Design Optimization Of Steel Liner-reinforced Concrete Penstock Based On ANSYS

Unique advantage of steel liner-reinforced concrete penstocks of hydropower stations is a kind of combination structure, it permit occuring radial crack in the concrete tube to maximizing Stress intensity of steel. Compared with penstock, it can reduce the thickness of steel liner, the sheet processing, installation difficulty, risk of accidents. Also it has economical use. This penstock is located on the downstream surface of concrete dam. The layout can less weaken the whole structure of the dam and avoid interruption between concrete pouring and penstock installation. The layout has been widely used at home and aboard. With the unceasing development of water and electricity enterprise of our country, daily increasing at scale of hydropower station in China, PD value of penstock is also growing. As a key structure building of hydropower station, operation security and structure stability of penstock are directly related to operation security and structure stability of the whole station. So it is of vital importance to analyze the stress state of penstocks accurately, select the thickness of steel liner and the ratio of concrete encasement einforcement reasonably.In this paper, the structure model of double steel liner-reinforced concrete penstocks is built and nonlinear analyzed by software named ANSYS and gained the structure style's echanical character and destroy mechanism of steel liner-reinforced concrete penstocks and analyzed its stress development process and carried on the optimization design using the optimized module provided by ANSYS in the favor of APDL,which is based on design principle, research fruits, model test and nonlinear analysis fruits of steel liner-reinforced concrete penstocks. Under the premise of ensuring structural safety and cracking value of concrete not more than allowable value, this paper does the optimization design to penstock. The results show that:1. Analyzing finite element analysis model of steel 1iner-reinforced concrete penstocks by ANSYS can consider the factors: concretes and steel bar correlation, materials behavior under multiple spindle stress condition, concretes dehiscence characteristic and so on. The results are better than the theory analytic method in engneer practice.2. Section forms of steel liner-reinforced concrete penstocks of hydropower stations have great influence on its stress distribution. And the results of the different element calculation models might differ greatly.3. In the process of optimizational design of steel- lined reinforced concrete penstocks of hydropower stations, Constraints are many and must be fully considered. It could not get optimal solution if constraints be omitted and incorrectly limited. While optimizing the amount of steel, maximizing Stress intensity of steel is unsuitable. Theoretically, it must be suitable for both the thickness of steel products determined by single security factor and concrete cracking conditions determined by stress intensity of steel products, which are favorable to structure security.4. Using the axisymmetric ring model during finite element analysis can easily draw the parameters of state variables when optimizing structure. The results obtained are more reliable. After structure optimization, the design variables of the section meet the restriction requirements of concrete surface crack to the maximum extent. However, the outer steel bar of the control section on waist of the square-round model probably appears the higher tensile stress and earlier yields. To prevent earlier yielding of the outer steel bar, there needs more steel products on the control section (about -30°～35°)on waist of square-round model.