The investigation herein focuses on studying the possibility of using recycled concrete aggregates in structural concrete. The study aims in investigating the uniaxial compressive, tensile and flexural strength of recycled aggregate concrete and behaviour of reinforced RAC beams by assessing several important aspects which may influence its behaviour. These aspects include the replacement percentage of recycled aggregates used in concrete and water to cement ratio. Concrete made with recycled concrete aggregates having replacement percentage of 0%, 30% 50%, 70% and 100% was used and were tested at 28 days curing. In general, it was found that increasing percentage of the recycled aggregates resulted in decrease in the concrete compressive, tensile and flexural strengths. However, the use of RAC as structural concrete can be justified by optimizing the replacement percentage of recycled concrete aggregates and water to cement ratio to get the desirable behaviour of reinforced concrete structures.
Use of Carbon Fibre Reinforced Polymer (CFRP) strips as externally bonded reinforcement, is a technically sound and practically efficient method of strengthening and upgrading reinforced concrete (RC) members. Externally bonded CFRP strips help in improving the structure performance by reducing deflections and/or cracking and increasing ultimate strength. The ultimate capacity of the strengthened beam is controlled by either compression crushing of concrete, rupture of CFRP and flexural shear cracking induced de-bonding atconcrete-CFRP interface. Present study deals with the use of externally bonded CFRP wraps instead of strips to strengthen RC beams in flexure with and without end anchorages. Six beams strengthened with CFRP wraps at bottom with and without anchorages, were tested with different a/d ratios. It was observed that use of CFRP wraps resulted in significantly increasing the stiffness and ductility of the RC beams along with increasing load carrying capacities of the strengthened RC beams with end anchorages.
Loads resulting from activities such as rock fall, heavy drop weights (for e.g. equipment's, heavy machines during installation), missile and aircraft interaction with slabs may results in loading intensity which have higher magnitude as compared to static loading. Based on the velocity of the impacting object at the time of contact, these activities may result in impact loading. Therefore, slabs designed should provide resistance to these accidental loading during their entire operational life. In this study, a dynamic non-linear finite element analyses were conducted to investigate the behavior of the reinforced concrete slabs subjected to high-mass low-velocity impacts. For this purpose, initially an already published impact test results were used to validate the numerical predictions. Following validation, a study was conducted to investigate the influence of the impact velocity on the behavior of the reinforced concrete slab. Based on the numerical investigation, it was found that the velocity of the impacting object has a significant influence on the behavior exhibited by slab under impact loading. Furthermore, it was also found that the behavior of slab under impact is both local and global. Local behavior is associated with the damage caused at the contact area of the slab and the impactor, whereas global behavior refers to the overall deformation of the slab when stress waves move away from the impact zone and travel towards the supports.
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