Study On The Reliability-based Optimization Design And Optimization Algorithm For Glass Fiber Reinforced Plastic Mortar Pipes

For the past few years,glass fiber reinforced plastic pipe(GFRP),which is a kind of composite pipe made of high strength and low density.For its advantages such as strong corrosion resistance,high strength and light weight required for underground pipes,it is gradually being noticed and studied in the field of civil engineering,and has become the application of municipal engineering hot spot.Many scholars from home and abroad have undertaken a substantial amount of experimental research on the performance and application of fiber-reinforced plastic pipes,and GFRP pipes are mainly used in municipal drainage and sewage,highway culverts and other fields.The application of glass fiber reinforced plastic pipe at home and abroad is becoming more and more extensive,and its production technology and mechanical properties are constantly optimized,among which the development prospect of glass fiber reinforced plastic mortar pipe(FRPM)is immeasurable.Although FRPM has many advantages,but in the pipeline design,economic cost,engineering applications,there are still many problems to be solved,we still need to do a huge amount of experimental research and exploration.At this time,the research on the mechanical properties of FRPM pipe culvert in China is still in the embryonic stage.In recent years,some scholars have analyzed the mechanical properties of FRPM pipe culvert under fatigue state and evaluated the safety of pipe culvert under vehicle load,etc.But there is less research on the structural optimization design content.In this thesis,based on the theory of composite material mechanics,the intrinsic structure model of FRPM sandwich pipe is established,the stiffness performance of each layer of the pipe wall is discussed,the reliability analysis of the pipe wall is carried out by using the Monte Carlo method,and finally the structural optimization of FRPM pipe culvert is suggested by using the improved whale algorithm,and the main work accomplished is as follows.(1)This thesis gives a systematic overview of the worldwide research status of FRPM pipe culverts,especially analyzes the latest research progress of domestic scholars,and analyzes the problems that need to be solved in the current research and proposes further research directions.The stress-strain relationship of fiber-wound composites is analyzed,and a principal structure model applicable to sand-laminated pipes is established with the characteristics of FRPM pipe culverts.(2)The structural reliability analysis model of FRPM pipe culvert is established.The basic theory of structural reliability and structural reliability calculation method are elaborated.Based on the analysis of unit layer reliability,the Tsai-Wu failure criterion and Tang failure criterion are used to evaluate the structural material damage modes based on the assumption of final layer failure,and the Monte Carlo simulation method is used to analyze and determine the main failure sequences of the laminated structure,and the system reliability of the FRPM pipe culvert is evaluated.(3)The Whale Optimization Algorithm was studied and analyzed,its convergence was improved,adaptive adjustment of weights was introduced to improve the optimization search process of the Whale Optimization Algorithm,and the improved Whale Optimization Algorithm was used for the first time to analyze the reliability optimization design problem of FRPM pipe laminated structure.