Structural Type Selection And The Analysis Of Static,Dynamic Characteristics About Large Diameter Steel Penstock

Steel penstock is the most basic way of water transfer for hydropower station.It has the advantages of clear force,convenient maintenance and repair,economic and safety,reliable structural analysis and so on,so it has been widely applied.The characteristics of penstock in hydropower station are under the high internal water pressure which is in the cycle of change,steep and close to the plant.In an accident,it will directly threaten the safety of the plant management personnel and facilities,even lead to secondary disasters.Therefore,it is very important to analyze the structural response of penstock under static and dynamic state in the background that there lack related research on the static and dynamic characteristics of large diameter penstock at present.The load on penstock in calculation process is relatively simple in the existing research.The influence of uneven temperature and lateral wind load on penstock is not considered.Bellows expansion joint is an important displacement compensation device in penstock,but there lacks comparative research on the location selection of the component so far.The traditional design of pressure pipe is often single steel pipe or reinforced concrete pipe.How to synthesize the two design forms in large diameter penstock needs to be analyzed.In this paper,three-dimensional nonlinear finite element numerical simulation analysis on static and dynamic characteristics of large diameter penstock is carried out with the help of commercially available finite element softwares like ANSYS and ABAQUS.The contents are as follows.1.The penstock's response under normal operating case with uniform temperature and internal pressure is calculated.The empty penstock's state under uneven temperature and lateral load is also analyzed.The structural responses among different schemes are compared.It shows that the state of penstock in different schemes is significantly different when it is empty.2.By contrasting the response of penstock in each scheme,the theoretical feasibility of setting bellows expansion joint at the middle part of two anchor blocks is demonstrated.The structure's response after downstream part of declining penstock is wrapped by concrete is compared with the scheme with no concrete.3.The changes about concrete's stress and displacement,steel pipe's stress and displacement,reinforcement of concrete structure caused by cushion layer which is set between concrete and steel pipe are analyzed.The feasibility of setting cushion layer in structure is analyzed.4.Considering the cracking damage and reinforcement of the concrete structure,the sensitivity analysis of the cushion layer's angle is carried out.By comparing the stress of steel pipe and concrete,the cracking condition of concrete,the force of steel bar under different cushion angles,the superior angle is put forward.5.Based on modal analysis and time history dynamic analysis,the dynamic responses of penstock in different schemes are summarized.Considering the previous analysis content,the superior scheme is put forward.