Structural Optimization And Seismic Performance Evaluation Of The Top Of Intake Tower Based On Endurance Time Analysis

The intake tower is the first structure in the entire water conservancy complex system.It is an important tower-shaped hydraulic structure outside the independent dam.It can be used as a water discharge structure for flood discharge and sand discharge,or as a water diversion structure Irrigation,water diversion and power generation.The intake tower plays an important role in the water conservancy project,and its seismic performance is very important to ensure the safety of the water conservancy project.However,due to the relatively few seismic damage data of the existing water intake tower under the action of strong earthquakes,the research on the impact of the tower hoist machine room on the seismic performance of the water intake tower under the action of earthquake is even rarer.It is imperative to evaluate the seismic performance of the intake tower of the top structure.This paper uses the KOYNA gravity dam to verify the applicability of the endurance time analysis method(ETA)for hydraulic structures.This method combines the advantages of pushover analysis method and incremental dynamic analysis method(IDA),and proposes a structural performance parameter that takes into account the cumulative development of damage to the intake tower under the action of strong earthquakes--the ratio of plastic energy consumption to total variable performance,provides a new idea for the evaluation of the seismic performance of the intake tower.The height and stiffness of the hoist machine room at the top of the tower are optimized,and the results are analyzed by quantile analysis and vulnerability analysis to evaluate the seismic performance of the intake tower.The research content of this article mainly includes the following aspects:(1)The incremental dynamic analysis of the KOYNA gravity dam in India was carried out,and the ratio of plastic energy consumption to total deformation energy,a structural performance parameter that can accurately describe the structural response under strong earthquakes,was obtained.The KOYNA gravity dam is subjected to nonlinear time history analysis by IDA method,and its IDA curve is obtained for quantile analysis and vulnerability analysis,and the corresponding limit state point and failure probability under the structural performance index are calculated.The comparison with earthquake damage examples and the research results of various experts and scholars verified the reliability and applicability of this index for hydraulic structures.(2)On the basis of the traditional performance-based seismic performance evaluation concept,a new seismic performance evaluation method-ETA method is used to perform nonlinear dynamic time history analysis of the KOYNA dam.In this paper,the concept and basic theory of the ETA method are discussed in detail,and multiple seismic time-history acceleration curves are synthesized according to its basic principles.The seismic analysis of the KOYNA dam is carried out,and the results of the incremental dynamic analysis are compared to obtain the ETA method.Get the advantages and disadvantages of the ETA method,its reliability and applicability to hydraulic structures are strongly demonstrated.(3)According to the basic theory of the ETA method,the endurance time analysis of the intake tower is carried out.Considering the influence of the hoisting machine room on the top of the intake tower on the tower body,the height and stiffness of the hoisting machine room on the top of the intake tower will affect the tower under the action of ground motion.The impact of the body is analyzed,and then a relatively stable structure of the hoist room is determined.The article describes the impact of the whiplash effect generated by the hoist room on the top of the intake tower on the damage of the tower body.The endurance time analysis of the Yangqu intake tower is carried out to explore the seismic response of the tower body under different heights and different stiffness of the hoist room.Through the analysis of the modal,displacement,energy and damage of the intake tower under the action of earthquake,the height and stiffness of the hoist room at the top of the intake tower are optimized to obtain a more reasonable height and stiffness of the hoist room.(4)According to the Yangqu intake tower optimization model obtained in Chapter 4,the endurance time analysis of the intake tower is carried out,and the probability analysis of the results is carried out considering the influence of the randomness of ground motion.Using the standard response spectrum given by my country’s hydraulic structure antiseismic design code as the target spectrum,according to the basic theory of the ETA method,15 three-dimensional seismic time history are generated,and the endurance time analysis of the intake tower is performed to generate the ETA curve.According to the failure criteria defined in Chapter 2,quantile analysis and vulnerability analysis of the results are carried out to evaluate the seismic performance of the intake tower and estimate the possible failure probability.