Safety Analysis Of The Large-Span Suspended Pipeline Structures

Suspension pipelines structure, the usual format of pipelines transportation, is consisted of main cable, anti-wind cable, tower base and anchor fastened system, truss bridge etc, main cable and anti-wind cable change their shape and dimension according to volume,location and distribution discipline of load, which belongs to typical large displacement and small distortion structure. The flexible character of cable-stayed structure decides its specialty of design on structure safety. According to the engineering background of Zhong-Wu natural gas transportation pipeline, this paper did some systematic analysis of gravity static stability, structural stability on the influence of static wind, structural stability in the situation of water pressure-experiment process,response of structure affected by earthquake ,etc, according to its structural safety design.At first, this paper established finite element model of suspension pipelines bridge separately based on finite element displacement theory by using commercial finite element software, according to engineering instance, and took the geometric nonlinearity factors into account such as initial internal force derived form permanent load of suspension pipelines bridge,drooping degree of cable, etc. Initial state of structure under the influence of gravity can be obtained through adjustment of initial strain of cable system, which gives initial rigidity to whole structure, and acted as the base of finite element analysis.Analysis of wind load acting is the important constituent part of security analysis of suspension structure , the influence of long span structure's geometric nonlinearity and nonlinearity of static wind load can not be neglected. Therefore, study on stability of long-span suspension pipelines structure under the influence of static wind is one of important directions of study on anti-wind capability of the structure. As a result, this paper acted load upon structure by using the method of dispersing static load on correlative nodes, and further with studying on safety activity of load applied on structure.Water pressure experiment is a static pressure trial, which is carried out before pipelines go into employ. In water pressure experiment, on the condition of winds not be taken into account, the load exerted on the whole structure is larger by far than state of employ, therefore it is necessary to do safety analysis of structure on the situation of water pressure experiment through simulated load of water gravity used to exert experiment.Inevitably, suspended pipelines, as the most important constitutes of long-span pipelines, is built in frequent earthquake area, as china is a frequent earthquake country. Analysis of dynamic behavior, seismic response and anti-seismic design become the most important problem of the suspend pipeline project, because of its big flexibleness, low damp and low natural frequency of vertical, horizontal bending and torsion vibration. This paper utilized the reading data of structures dynamic property based on its analysis and time process analysis method was used based on directly dynamic analysis theory, aiming at the strongly nonlinear character of long span flexible structure of suspension pipelines spans, which can be used to grapple those important information associated with structural vibration model and its reactive maximum value, and gave the useful reference to anti-quake design of structure.