The theoretical basis of an approximate procedure for assessing the effects of mudslides on buried marine pipelines is presented. The procedure has the capability to account for geometric nonlinearities (i.e., large-displacement “cablelike” behavior of the pipeline), nonlinear longitudinal soil restraint against pipeline pull-out, and a limited degree of nonlinear pipe material behavior. The analytical approach is based upon a variational work method known as the Theorem of Stationary Total Potential and is simpler and easier to employ than a nonlinear finite element code, while generally yielding good approximations to pipeline stresses and strains. The validity of the procedure is demonstrated for a typical mudslide situation through comparison with results of nonlinear finite element analyses.
Impact analysis of nuclear plant structural walls composed of surface steel plates, tie-bars, shear studs and concrete are discussed utilizing a simplified model of a fictitious wall to perform the analysis using LS-DYNA. The concrete constitutive model is based on Winfrith concrete model which covers all aspects of concrete behavior including cracking. The model was used to conduct a series of numerical studies to evaluate the effect of several parameters affecting the behavior of the wall. These parameters include thickness of the wall, thickness of the steel plate and diameter of tie bars. These studies resulted in several conclusions regarding the global and local behavior of the steel plated concrete wall system.
Overhead protection (OHP) structures are used by major oil operators and government agencies in terrorist affected areas to protect facilities housing their personnel such as office facilities and dining facilities. Structural design of OHP structures to resist blast/fragment loads by 120 mm mortars and rockets is presented in this paper. The OHP structure consists of two layers: a pre-detonation layer and a shielding layer. The pre-detonation layer consists of plywood supported by steel beams, and this will cause the ordnance to explode upon impact. The shielding layer underneath consists of steel plates and sand bags supported by steel frames. The sand bags are intended to stop the fragmentation of the mortars or rockets while the steel plates and the supporting structural frames will resist the blast and impact loads. The blast and fragment loads caused by 120 mm mortar and rockets were calculated, and the required plywood thickness and sand bag thickness were determined. A finite element model for the OHP structure was developed using the general-purpose finite element program ABAQUS/Standard, and the structure was evaluated for the blast loads using the procedures in 2010 ASCE Guidelines, "Design of Blast Resistant Buildings in Petrochemical Facilities". In addition, the OHP structure was also evaluated for normal design loads such as wind loads and seismic loads based on 2006 International Building Code.
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