عنوان مقاله [English]
The buried oil and gas pipeline is one of the most vulnerable infrastructures. Underground structures are among the most vital infrastructures, which include a variety of tunnels, subway lines, gas, oil, and water pipe. The analysis and design of gas and oil pipelines are of importance, because they are long and go through lands with various characteristics and that they are laid beside the faults and sometimes cross the faults. Various studies have already investigated the design process and the damages imposed on the pipelines crossing the faults. Moreover, plenty of studies have been devoted to the investigation of the effect of wave propagation method on the seismic behavior of steel pipelines. Underground structures are entitled to particular analytical conditions due to their length and continuity. Furthermore, their design and implementation are of utmost importance due to the high and strategic costs of repair and the threats and damages to the people's lives after the earthquake. This paper focuses on the three dimensional modeling of transmission pipelines with the length of 1000 meters, in a way that the effect of boundary conditions on the responses is insignificant. Nonlinear springs were employed to model the soil, considering the ASCE equations as well as
taking soil-pipe slippage into consideration. This paper also aims to investigate the effect of (longitude) P-wave propagation on the amount of strain belonging to steel pipeline made of x60. To this end, MATLAB and ABAQUS software was used to carry out numerical analysis. The results show that the speed of wave propagation as well as accelerograph frequency content significantly affects the responses and amounts of strain in soils whose speed in hard soils with higher wave propagation is less than that of looser soil with lesser wave propagation.