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 optimizationprocess;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 54tons to 25tons after 10 optimization cycles to maintain a weight of 18.532t.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 connect247979 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.