Simulation Of Cable-stayed Pipelines Based On Risk

ABSTRACT:With the development of pipeline transport, mileages of long-distance natural gas pipelines are expanding. Therefore, the risk of accidents is also increasing. Cable-stayed span is one of the common ways to cross rivers in long-distance pipelines and it is so significant that often regarded as a throat of the long distance transmission pipelines. Once an accident occurs, not only the mining and transportation of oil and gas fields will be affected, but also serious environmental pollution will be happened, resulting in huge economic losses and social impacts. In order to ensure safety operation of pipelines, the related research on cable-stayed pipelines should be carried out.As cable-stayed pipeline bridge is a typical non-linear structure, an updated Lagrangian formulation (U. L. Formulation) method for nonlinear finite element analysis was adopted in this paper, and Newton-Raphson iterative method for the numerical simulation was selected. To verify the feasibility of preparation of finite element computer program, a1/14scale model of cable-stayed pipeline bridge had been built. From the comparison results between model experimental tests and finite element analysis program, it showed that the displacement and stress variation of pipeline in the two methods were in a good agreement. Therefore, the subsequent simulation can be conducted and realized organic integration between the model test and software simulation.’Chongqing Line’Fujiang cable-stayed pipeline bridge was taken as a research object and the finite element program was compiled. The displacement and stress-strain of the pipeline in the effect of snow load (snow, moderate snow, heavy snow and blizzard), wind load (3m/s,6m/s and20m/s), water hammer, and seismic loads were mainly studied in this paper. The results show that the displacement and stress of pipeline bridge increase with the increasing snow load and wind. The maximum displacement locates in the mid-span location and the stress of pipeline in the compensation and side spans is larger than the others. During the water hammer analysis, increment of the flow rate, surge pressure and other key parameters were calculated, the maximum stress was obtained (195.66MPa) which occurs at the level of facing stream side in the left compensation by using the response spectrum analysis method. During the wind-induced vibration study, the dynamic response of the pipeline bridge at the average wind speed (2.67m/s) in the sub-critical range was researched and the results show that cable-stayed pipeline bridge structure is sensitive of the low-wind load and easy to produce a slight vibration. Therefore, some measures should be taken to avoid vibration fatigue. Using history response method, the vibration response of the pipeline bridge under seismic waves in earthquake simulation was reproduced, and the effect of imposing a one-dimensional seismic wave on the cable-stayed pipe bridge structure in different direction was compared. The analysis reveals that the cable-stayed pipe bridge is more sensitive to shear wave load in a certain magnitude, but overall, the pipe bridge have a strong seismic performance mainly due to its flexible system. The cable-stayed pipeline bridge is checked according to the relevant strength theories, weak links of the structure are found, and some improvement measures are put forward, which can propose bases for stable operation of other cable-stayed pipelines in-service.The results of this study not only provide technical support for the design of cable-stayed pipeline bridges structure, but also put forword reliable analysis of research methods and related data for safe and reliable operation of the similar cable-stayed pipeline bridges.