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Go to Editorial ManagerThis study investigates the shear strength behavior of two-layer reinforced concrete beams consisting of two different types of concrete. One of the layers made of lightweight concrete (LWC) and the other was normal weight concrete (NWC). A total of 16 shear deficient reinforced concrete beams were fabricated and cast with NWC, LWC, and two-layer beam of both material with different configuration. All the beams were tested under four-point loading after 28 days. The variables of the experimental program include the ratio of thickness of the lightweight concrete layer to the overall depth of beam ( h LW / h ), and concrete compressive strength. Experimental results which include load-deflection response curves along with failure modes for NWC, LWC and two-layer beams. The results showed that all beams failed in a similar mode, due to diagonal tension shear crack. Based on the experimental results it can be also concluded that the shear load is governed by compressive strength of lower layer of the concrete when the shear span to overall depth ( a / h ) of the beams is 2.75 or more. While for the a / h 2.375 and 2.00 the two-layer beam has a significant reduction in the shear capacity compared to the NWC beams and increasing compared to LWC beam. The ratio of experimental shear stress divided by the root square of concrete compressive strength (vexp √f c ' ) , which demonstrates the diagonally cracked concrete's ability to transfer strain and shear was maintained for all configurations greater than 0.17, which is the minimal value recommended by ACI318-19.
Submarine pipelines are essentially used for the transmission of gas and oil across oceans between countries or for transport between shore and offshore installations. The pipeline applications were studied to be installed in deep water, which exposed to different loads such as currents and waves in various directions, barge movements, seafloor interaction, etc. This paper developed a dynamic analysis of the J-lay suspended submarine pipeline during laying, taking into account the effect of water depth, the direction of the wave heading, and sea state without vessel movement. The finite element program ANSYS R17.2 is used for modeling and analysis of the pipelines. The random sea state is modeled using the JONSWAP spectrum. It was found that the effect of the direction of wave heading on the bending moment from dynamic analysis of pipeline is obvious in a depth of (2 m) below water surface, and then gradually decreases until it disappears in depth of (100 m). Whereas the effect of wave height is obvious in a depth of (2 m) and then gradually decreases until it disappears in depth of (120 m).