Society for Earthquake and Civil Engineering Dynamics lecture
Dr Dimitris Karamitros, University of Bristol
One Great George Street, Westminster, London SW1P 3AA
On 24 February 2016, Dr Dimitris Karamitros will give a lecture on the Design of Buried Pipelines against Permanent Ground Displacements, hosted by the Society For Earthquake and Civil Engineering Dynamics.
Permanent ground displacements (PGDs) consist one of the most critical loading conditions that need to be taken into account for the design of buried pipelines. In earthquake-prone areas, such displacements are mainly associated to fault rupture, sloping ground failure, or liquefaction-induced lateral spreading. Nevertheless, they may also originate from underground works (e.g. tunneling), differential settlement (e.g. due to lowering of the groundwater table) or heave (e.g. expansive soils undergoing large climatic variations). Especially in the case of step-like deformations, the axial and bending strains developing on the pipeline may become fairly large and lead to rupture, either due to tension or due to buckling. Apart from the detrimental effects that such a rupture can have to social and economic activities, the ecological disaster that may result from the leakage of environmentally hazardous materials should also be highlighted.
The numerical techniques currently utilized in practice for the rigorous performance-based design of pipelines will be initially reviewed. Attention will be drawn to the importance of accurately modelling the non-linear behaviour of pipeline steel, non-linear soil-pipeline interaction effects and second order effects induced by large displacements, which make the corresponding numerical analyses highly demanding in terms of both expertise and computational effort. Emphasis will be then given to recently-developed simplified analytical methodologies for the estimation of the developing pipeline strains. A series of methodologies will be presented, focusing on strike-slip, normal and oblique fault crossings, as well as on cases of differential settlement or heave. These methodologies are based on simple equilibrium and displacement compatibility equations to derive the axial forces applied to the pipeline, while they adopt a combination of beam-on-elastic-foundation and elastic-beam theory to calculate the developing bending moments. Large-displacement non-linearities are indirectly taken into account, while material non-linearities are introduced through an equivalent-linear iterative solution scheme that considers the actual distribution of stresses on the pipeline cross-section. Furthermore, attention will be drawn to the effect of bends existing within the pipeline’s unanchored length, where the pipeline strains may even exceed the strains developing at the PGD zone and become critical for the design.
Based on comparisons with benchmark numerical analyses, it will be demonstrated that the proposed simplified methodologies provide fairly accurate predictions while remaining relatively easy to program and utilize, at least for preliminary design and verification purposes. Finally, the insight provided by the analytical solutions will reveal a number of conclusions of practical interest to pipeline design applications.
This event will be held at the Institution of Civil Engineers, 1 Great George Street, Westminster, London, SW1P 3AA. Non-members are welcome to attend, and there is no charge for attendance. Seats will be allocated on a first come, first served basis.
For further information please contact Greg James, Associated Societies Executive, at the ICE on Tel: +44 (0) 20 7665 2229020 7665 2229, or Fax +44 (0) 20 7799 1325 or Email: firstname.lastname@example.org.