桁架式跨河管架的优化设计及地震可靠性评价
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摘要
在管道穿跨越工程中,桁架式跨河管架是一种常见形式。本文在结构优化设计中分别对矩形桁架结构和倒三角形桁架结构两种方案进行优化,并对优化结果进行了比较分析,确定了结构最优方案。通过模拟结构在地震作用下的响应对结构的抗震性能进行了分析,并通过可靠性分析评价了结构的抗震可靠度。结果表明:适当增加结构高度和减小结构宽度对结构有利;结构的总重量随杆件截面尺寸的减小而迅速降低,10次优化循环后即从54t降至24t左右;三角形桁架比矩形桁架结构简单,重量减轻36%;可靠性分析表明结构的可靠度为99%。
Oil and gas pipeline construction persists throughout China on national and regional levels.Because many barriers are encountered such as rivers,lakes,mountains,canyons,other construction,and unstable strata,access through and across these barriers are important in oil pipeline engineering design.Thus,construction reliability,safety,and economic impact have been studied.In cross projects,truss-type river-crossing pipe rack is a common form of medium-sized cross-projects because it has a simple structure,is light weight,and provides a convenient way to repair pipelines with ample space.The structure design optimization and seismic reliability analysis of truss-type river-crossing pipe racks are related to the overall performance and safe operation of pipeline structures.In this study,two scenarios of rectangular and inverted triangle truss structures were respectively optimized by using ANSYS parameter design language and a design optimization module,and the optimization results were analyzed to determine the most optimal solution.By simulating the structure's earthquake response,seismic performance analysis was conducted,and the structure of anti-seismic reliability was obtained through reliability analysis for optimal structure design. The optimization results show that the height of the truss increases in the optimization process;however,the width is reduced.In addition,the diameter of pole gradually decreases in the process.The total weight of the structure rapidly reduces with rod cross-section reduction;reduction is rapid in the first three optimization cycles and slows from 54 tons to 25 tons after 10 optimization cycles to maintain a weight of 18.532 t.The analysis of internal force and largest structural displacement show that the structures make full use of material mechanics capability and that the appropriate increase in structural height and decrease in structural width are favorable to the structure.Optimization results show that the two types of structure forms show the same change trends in the optimization.The inversion triangle form has a more simple structure,fewer section species,and a more simple connect node construction than those of the rectangle form.Moreover,the inversion triangle form has weight reduction of 36% over the rectangle form;therefore,the cost of material and construction is less,and mechanics capability is more effective. Response spectrum and time history analyses reveal that earthquake activity in the horizontal direction results in stronger activity on the river-crossing pipe rack than that in the vertical direction because the width of the truss decreases in the optimization to increase vertical stiffness. Reliability analysis shows that the reliability of the structure is 99%.Failure probability of the structure maintains the probability permission bound of construction design.Therefore,the entire structure retains the guarantee probability of 99%.That is,the structure is safe and reliable under the earthquake activity and load. This study provides particular methods of using the ANSYS program for design optimization and seismic reliability analysis,which are helpful for maintaining construction expenses and operation safety.
Oil and gas pipeline construction persists throughout China on national and regional levels.Because many barriers are encountered such as rivers,lakes,mountains,canyons,other construction,and unstable strata,access through and across these barriers are important in oil pipeline engineering design.Thus,construction reliability,safety,and economic impact have been studied.In cross projects,truss-type river-crossing pipe rack is a common form of medium-sized cross-projects because it has a simple structure,is light weight,and provides a convenient way to repair pipelines with ample space.The structure design optimization and seismic reliability analysis of truss-type river-crossing pipe racks are related to the overall performance and safe operation of pipeline structures.In this study,two scenarios of rectangular and inverted triangle truss structures were respectively optimized by using ANSYS parameter design language and a design optimization module,and the optimization results were analyzed to determine the most optimal solution.By simulating the structure's earthquake response,seismic performance analysis was conducted,and the structure of anti-seismic reliability was obtained through reliability analysis for optimal structure design. The optimization results show that the height of the truss increases in the optimization process;however,the width is reduced.In addition,the diameter of pole gradually decreases in the process.The total weight of the structure rapidly reduces with rod cross-section reduction;reduction is rapid in the first three optimization cycles and slows from 54 tons to 25 tons after 10 optimization cycles to maintain a weight of 18.532 t.The analysis of internal force and largest structural displacement show that the structures make full use of material mechanics capability and that the appropriate increase in structural height and decrease in structural width are favorable to the structure.Optimization results show that the two types of structure forms show the same change trends in the optimization.The inversion triangle form has a more simple structure,fewer section species,and a more simple connect node construction than those of the rectangle form.Moreover,the inversion triangle form has weight reduction of 36% over the rectangle form;therefore,the cost of material and construction is less,and mechanics capability is more effective. Response spectrum and time history analyses reveal that earthquake activity in the horizontal direction results in stronger activity on the river-crossing pipe rack than that in the vertical direction because the width of the truss decreases in the optimization to increase vertical stiffness. Reliability analysis shows that the reliability of the structure is 99%.Failure probability of the structure maintains the probability permission bound of construction design.Therefore,the entire structure retains the guarantee probability of 99%.That is,the structure is safe and reliable under the earthquake activity and load. This study provides particular methods of using the ANSYS program for design optimization and seismic reliability analysis,which are helpful for maintaining construction expenses and operation safety.
引文
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[4]薛强.管道跨越设计简介[J].天然气与石油,1999,17(2):27-30.XUAN Qiang.Pipeline Crossing Design Presentation[J].Natu-ral Gas and Petroleum,1999,17(2):27-30.
[5]史睿,刘延强.巴东支井河输气管道桁架跨越结构的优化设计分析[J].石油工程建设,2009,35(4):24-27.SHI Rui,LIU Yan-qiang.Optimization Analysis for Truss Over-head Crossing Design of Zhijing River Gas Transmission Pipeline[J].Petroleum Engineering construction,2009,35(4):24-27.
[6]詹胜文,刘晓峰,程梦鹏,等.忠武输气管道桁架梁式跨越设计的改进[J].油气储运,2005,24(4):32-34.ZHAN Sheng-wen,LIU Xiao-feng,CHENG Meng-peng.Im-provement on Truss Overhead Crossing Design for Zhongxian-Wuhan Gas Transmission Pipeline[J].Oil&Gas Storage andTransportation,2005,24(4):32-34.
[7]曹青,张豪.考虑土-结构相互作用的风力发电机塔架地震响应分析[J].西北地震学报,2011,33(1):62-66.CAO Qing,ZHANG Hao.Seismic Response Analysis of WindTurbine Tower with Soil-structure Interaction[J].NorthwesternSeismological Journal,2011,33(1):62-66.
[8]L A Schmitt.Structural Design by Systematic Synthesis[A]∥Proc.2nd Conf.Electronic Comp,ASCE[C].New York:[s.n.],1960:105-122.
[9]刘爱霞.导管架式海洋平台模型修正技术的研究[D].青岛:中国海洋大学,2006.LIU Ai-xia.The Studies on Model Updating for Offshore Plat-forms[D].Qingdao:Ocean University of China,2006.
[10]庄向仕.桁架式跨河管架的地震可靠性评价及优化设计[D].青岛:中国石油大学,2010.ZHUANG Xiang-shi.Seismic Reliability Analysis and Optimi-zation of Truss-type River-crossing Pipe Rack[D].Qingdao:China University of Petroleum,2010
[2]杜永峰,余钰.重力式挡土墙结构体系可靠度的Monte Carlo模拟[J].西北地震学报,2012,34(1):29-32.DU Yong-feng,YU Yu.Monte Carlo Simulation of System Re-liability of Gravity Retaining Wall[J].Northwestern Seismolog-ical Journal,2012,34(1):29-32.
[3]胡道华,杨晓秋.桁架式跨越通过高地震烈度区的抗震分析[J].油气储运,2011,30(6):453-455.HU Dao-hua,YANG Xiao-qiu.The Seismic Analysis of Trussthrough High Seismic Intensity Area[J].Oil&Gas Storage andTransportation,2011,30(6):453-455.
[4]薛强.管道跨越设计简介[J].天然气与石油,1999,17(2):27-30.XUAN Qiang.Pipeline Crossing Design Presentation[J].Natu-ral Gas and Petroleum,1999,17(2):27-30.
[5]史睿,刘延强.巴东支井河输气管道桁架跨越结构的优化设计分析[J].石油工程建设,2009,35(4):24-27.SHI Rui,LIU Yan-qiang.Optimization Analysis for Truss Over-head Crossing Design of Zhijing River Gas Transmission Pipeline[J].Petroleum Engineering construction,2009,35(4):24-27.
[6]詹胜文,刘晓峰,程梦鹏,等.忠武输气管道桁架梁式跨越设计的改进[J].油气储运,2005,24(4):32-34.ZHAN Sheng-wen,LIU Xiao-feng,CHENG Meng-peng.Im-provement on Truss Overhead Crossing Design for Zhongxian-Wuhan Gas Transmission Pipeline[J].Oil&Gas Storage andTransportation,2005,24(4):32-34.
[7]曹青,张豪.考虑土-结构相互作用的风力发电机塔架地震响应分析[J].西北地震学报,2011,33(1):62-66.CAO Qing,ZHANG Hao.Seismic Response Analysis of WindTurbine Tower with Soil-structure Interaction[J].NorthwesternSeismological Journal,2011,33(1):62-66.
[8]L A Schmitt.Structural Design by Systematic Synthesis[A]∥Proc.2nd Conf.Electronic Comp,ASCE[C].New York:[s.n.],1960:105-122.
[9]刘爱霞.导管架式海洋平台模型修正技术的研究[D].青岛:中国海洋大学,2006.LIU Ai-xia.The Studies on Model Updating for Offshore Plat-forms[D].Qingdao:Ocean University of China,2006.
[10]庄向仕.桁架式跨河管架的地震可靠性评价及优化设计[D].青岛:中国石油大学,2010.ZHUANG Xiang-shi.Seismic Reliability Analysis and Optimi-zation of Truss-type River-crossing Pipe Rack[D].Qingdao:China University of Petroleum,2010
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