Sensitivity Analysis of Buried Jointed Pipelines Subjected to Earthquake Waves

In this study, a number of nonlinear time-history dynamic analyses are conducted on a part of Tehran water distribution network to investigate its functionality during transient large ground motions. The network is of 950-meter length, consisting of ductile iron pipes segments of 6-meter length. Pipes are modeled using beam elements and springs characterize the connections. Considering the time lag between support inputs, and the nonlinear soil-pipe interaction, by scaling the amplitude of the Tab as earthquake record, incremental dynamic analysis is carried out on the network in two orthogonal directions and the sensitivity of the network response is examined. Furthermore, the effects of variations in soil damping and soil spring stiffness are also studied in the network analysis. Finally the effect of changes in angle between incoming wave and pipeline is considered on a simplified network. Results show that the points other than critical ones at network intersections remain almost intact and when the angle of incidence is 30 degrees the stress and rotation peak.

Evaluation of Water Distribution Jointed Pipe Networks under Transient Ground Motions

In this study, a new method is proposed to evaluate the seismic behavior of buried jointed water pipeline networks subjected to wave propagation. First, using finite element method and solid elements, different kinds of currently used connections in the network are modeled, and their nonlinear behavior in all directions is obtained. Second, a 950-meter long network consisting of ductile iron pipes segments of 6-meter length and springs characterizing the connections, are modeled using beam elements. Three-component displacement record of the Tabas earthquake is applied to the network considering the time lag between support inputs, and the nonlinear soil-pipe interaction. The record is applied once in North-South direction and once in East-West direction with different wave propagation velocities. Results of interest such as stress values and rotations at various points of the network are then obtained, and critical points are introduced in each direction. Results show that the points other than the critical ones at the network intersections remain elastic.