The variation of reinforcement details, confinement and joints angle are considerable factors which affect the ultimate limit moment of joints and joints efficiency. The variation of joint size is another factor that significantly affects the ultimate limit moment of joints and frame joints efficiency. These previous factors were not considered in design. Corners may be subjected to closing moments, which subject to tensile stresses in the outside of the corner, or to opening moments, which cause tensile stresses in the inside of the corner. The last type of moments arise more detailing problems. Opening joints may be found in retaining walls water tanks, open channels, bridge abutments, high rises due to wind effect, frame structures, etc. in the other hand the closing joint may be found in two hinged and fixed frames and underground water tanks. Hence two types of joints should be compared.The presented paper introduces an experimental and analytical study in order to investigate the effect of reinforcement details, confinement, joints size, joints angle on the frame joints efficiency and comparison between closing joints and opening joints. Experimentally, a total of eleven specimens were tested under vertical load. All specimens were tested up to failure and the behaviour was fully monitored. Moreover, a nonlinear 3D-finite element analysis was established using ABAQUS program and verified with the experimental results in order to give design recommendations for those structural elements.
Abstract:Strengthening of RC structures with externally bonded FRP (fiber reinforced polymers) has become an important challenge in civil engineering. Epoxy is the main bonding agent used so far, but in the case of a fire, it is subjected to complete loss of his bonding capabilities. Mineral based composites strengthening systems consist of FRPs and a cementitious bonding agent which form a repair or strengthening system that is more compatible with the concrete substrata, and roved its efficiency. The current research introduces the use of a special cementitious material "Grancrete" as a bonding agent. Test results of 32 T-section RC beams strengthened with various FRG (fiber reinforced Grancrete) strengthening systems are presented. The results demonstrated that most of the specimens were likely to fail by debonding of the FRP from the concrete either at the ends or at intermediate flexural cracks. This paper presents an in-depth study aimed at the development of a better understanding of debonding failures in RC beams strengthened with externally bonded FRP systems. Different analytical models, published in the literature for plate end debonding, are reviewed and compared to test results. The results also demonstrated that when using U-wraps, the specimens were likely to fail by FRP sheet rupture.
Sustainability, nature conservation, and energy economy remain the significant points of the global community focus. Due to the rapid growth in the world wide consumption of limited conventional energy and the environmental consideration for refrigerant agents' choice, solar-driven adsorption refrigerators (SAR) have been the focal of extensive research for cooling and refrigeration applications subjected to meet the fast increase in refrigeration needs of the developing countries such as Egypt. A new two composite adsorbents consist of 95wt% silica gel powder with 5wt% activated carbon powder (SGC1) and 90wt% silica gel powder with 10wt% activated carbon powder (SGC2), used with water as a refrigerant agent in a solar adsorption refrigerator installed in Upper Egypt. These adsorbents were evaluated as eco-friendly and low-cost cooling storage for cooling fruits and vegetables within a convenient storage environment. The experiments were done under the weather conditions of Qena City in Upper Egypt. The main results showed that the best obtained coefficient of performance (COP) was about 0.174 for SGC1. The specific cooling power (SCP) value was about 0.0199 kW/kg for SGC1. Moreover, the delivered evaporator temperature by the adsorption refrigerator can reach about 2.8-1.6°C. These results revealed that the proposed new adsorbents are beneficial for storing vegetables and fruits in remote and rural areas where electrical power sources are insufficient or unavailable.
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