The Effect of P-Wave Propagation on the Seismic Behavior of Steel Pipelines

Underground structures perceived as one the most vital infrastructures,which include a variety of tunnels, subway lines,gas, oil and water pipe. Plenty of studies devoted to the investigationof the effect of wave propagation method on the seismicbehavior of steel pipelines. It should be mentioned thatanalyses have been carried out on both clayey and sandy soilwith different propagation speed in each of them. The aim ofthis research is the investigation of the effect of longitudinalp-wave propagation method on the amount of nonlinear strainsof pipeline with different way such as Pipe and Psi element or2D modelling of soil. It became evident that the amounts ofMaximum tension strain produced in the pipe have the maximumdifference, equaling 3.4 per cent. In addition, it investigatesthe effect of frequency of input motion on nonlinearstrains and the effect of frequency content in the results. &nbsp

The Effect of Three-Dimensional Earthquake P-Wave Propagational Speed on Buried Continues Straight Steel Pipelines

The analysis and design of gas and oil pipelines is of importance given the fact that they are long and go through lands. They are laid besides 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. The aim of this research is studying the effect of longitudinal wave propagation method on the amount of nonlinear strains of pipeline. In addition, it investigates the effect of wave propagation speed as well as the simplified hypothesis of the same effect of the wave on the pipeline. Many researchers study on modal analyses or two-dimensional analyses. In this paper used three-dimensional modeling with propagational P-wave. It should be mentioned that analyses carried out on both clayey and sandy soil with different propagational speed in each of them. The accuracy of the proposed analyses is validated by the comparison of the proposed solution results with some existing solutions.  According to the analyses, it became obvious that in dense soil the amounts of strain are less than soft soil. This amounts to 71 per cent in a sinusoidal wave. The average of the values of the reduced strain in different type of soil could reduce the amount of strain to be considered equal to 0.592 for clayey soils, and equal to 0.61 for sandy soil

A Comparative Experimental Study on the Flexural Behavior of Geopolymer Concrete Beams Reinforced with FRP Bars

An environmentally friendly building system with suitable properties including durability can be made by using geopolymer concrete and FRP bars. The flexural behavior of geopolymer concrete beams made from Iran mines soil and reinforced with FRP and steel bars was examined in this work. In terms of reinforcement and concrete, the findings of the experimental investigation of geopolymer concrete beams were compared to those of standard cement concrete beams. To accomplish this purpose, a four-point flexural test was performed on 24 specimens of geopolymer and cement concrete beams reinforced with steel, GFRP, and CFRP bars. The initial cracking load, ultimate load, failure modes, number and width of cracks, load-deflection behavior, crack pattern, strain distribution, effective moment of inertia, and ductility were all investigated. The failure modes of tested beams were approximately similar to those predicted by codes, and a comparison of experimental findings with codes predictions reveals that these codes underestimated the beams' flexural strength, but ACI predictions are almost 20% more accurate than CSA ones. Geopolymer beams reinforced with FRP rebars and made with Iran mine soil showed similar results to reinforced cement beams, and the ductility ratio of FRP and steel reinforced geopolymer beams is 5% and 34% greater than that of reinforced OPC concrete, respectively

Non-linear Dynamic Analysis of Steel Hollow I-core Sandwich Panel under Air Blast Loading

In this paper, the non-linear dynamic response of novel steel sandwich panel with hollow I-core subjected to blast loading was studied. Special emphasis is placed on the evaluation of midpoint displacements and energy dissipation of the models. Several parameters such as boundary conditions, strain rate, mesh dependency and asymmetrical loading are considered in this study. The material and geometric non-linearities are also considered in the numerical simulation. The results obtained are compared with available experimental data to verify the developed FE model. Modeling techniques are described in detail. According to the results, sandwich panels with hollow I-core allowed more plastic deformation and energy dissipation and less midpoint displacement than conventional I-core sandwich panels and also equivalent solid plate with the same weight and material