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Liquid storage, particularly oil and petrochemical products which are considered hazardous liquid, are an important part of the oil industry. Thin-walled vertical cylindrical steel storage tanks are widely used in recent years. Due to high sensitivity of these structures in an earthquake and other external excitations may lead to catastrophic consequences. For instance, huge economic losses, environmental damages, and casualities, many studies have been done about these structures. past studies showed that liquid storage tanks, equipped with a floating roof, are potentially vulnerable while subjected to seismic loads and earthquake has been considered as one of the most destructive natural hazards. The reason is that such tanks are made of two separated parts (shell and roof) which each may have its own responses; sometimes causing resonance phenomenon and so that, roof movements, rooffluid interaction, roof-shell interaction, and also the way they are attached should still be investigated. Experimental tests of floating roof 's vertical fluctuation was performed in a full-scale reservoir tank and assessing of the results demonstrated that presence of a seal between floating roof and shell plate can significantly increase damping ratio in liquid sloshing and also suppress the roofs vertical displacements. In other words, seal can control a floating roof and make it stop moving vertically over few cycles. [ABSTRACT FROM AUTHOR]

Determining the failure criteria and the level of damage in buriedpipelines is an important and significant issue and differentresearchers have studied continuous and segmented steeland concrete pipes. To calculate the failure criterion of GlassReinforced Polymer (GRP) pipes, first the pipe was tested andthe force-displacement diagram of the pipe was drawn up untilthe failure time. Then, the tested specimen was modelled usingfinite element software and the lab test results were verifiedquite accurately. Based on this, by the finite element modelingof GRP pipe with different diameters under bending, the pipe’sfailure criterion was calculated. Afterwards, straight GRPpipes with different diameters were subjected to landslide andearthquake wave propagation in different clay and sandy soils.The results of finite element analyses in eight different types ofsoil show the vulnerability of the GRP pipes. [ABSTRACT FROM AUTHOR]

Pipe-Soil interaction presents a challenging problem of analysis and design of buried pipelines. Even though the accuracy of ASCE relations for calculating pipe-soil interaction is good in certain cases as a number of researchers have demonstrated those relations are rather inaccurate for other cases such as under fault movement. This research evaluates the interaction between sandy soil and polyethylene pipes subjected to strike-slip faulting using a non-linear finite element numerical model. Upon verification of the results of the numerical model using previously conducted experiments, several numerical studies analyses were carried out for pipes with different diameters, thicknesses and burial depths. The results suggest that the pipe thickness and the fault-pipe angle affect the pipe-soil interaction. Such effects are not reflected in the ASCE relations considerably. Finally, based on the results obtained, the ASCE relation for the transverse-horizontal interaction between sandy soil and polyethylene pipes subjected to strike-slip faulting was modified. [ABSTRACT FROM AUTHOR]

Modification of the asphalt mixture is one approach used to achieve good mixtures. Fibers and polymers are generally two important modifiers in improving pavement performance, though fibers have received much attention for their enhancement effects among other modifiers for asphalt. In this research by evaluating various methods of Polypropylene fibers mixing in asphalt mixture and choosing the most suitable one, adding 0.1 to 0.5 of Polypropylene fibers contents in asphalt mixtures based on Topeka aggregation are studied. The results indicated that polypropylene has direct ratio to increasing of Marshall Stability, VTM and VMA and has reverse ratio to decreasing of Flow, VFA and Unit Weight. These results are because of fiber's resistive properties, absorption by bitumen and aggregates and also chemical reactions in the mixture. This modifier causes improvement in asphalt physical and mechanical properties based on Topeka aggregation. By considering polypropylene's applications, usage of it in highways with heavy traffic can be discussed in order to increasing pavement life. [ABSTRACT FROM AUTHOR]