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Go to Editorial ManagerThis paper presents experimental investigations to study the behavior of High Strength Reinforced Concrete (HSRC) deep beams with web openings under monotonic and static repeated loading conditions. The experimental work procedure consisted of testing eighteen simply supported HSRC deep beams both with and without web openings. The numerical work procedure consisted of testing ten simply supported HSRC deep beams both with web openings. All beams had the same dimensions and flexural reinforcement. They had an overall length of 1400 mm, a width of 150 mm and a height of 400 mm. The investigated test parameters were concrete compressive strength, shape and size of openings, vertical and horizontal reinforcement ratios, shear span to effective depth ratio (a/d ratio) and loading history. The experimental results reveal that the ultimate load capacities for specimens tested under four different repeated loading regimes decrease in the range between 2% and 19% in regards to the control specimens which were tested under monotonic loading regime. The results indicated that the increase in the severity of loading history leads to a decrease in the ultimate shear strength of the deep beams and causes increases in their ductility ratio. The ultimate loads of HSRC deep beams with square web openings size of (50*50mm, 60*60mm and 70*70mm) tested under the repeated loading history (HS-1) which consisting of five phases decreased by (11.4 %, 24.1% and 26.3 %, respectively) compared to that of identical solid deep beam. The ultimate load of HSCR deep beam with circular web openings shape tested under repeated loading history (HS-1) increases by 8.6 % compared to the equivalent square web openings shape. For numerically analyzed beams under repeated loading history (HS-1), the ultimate load increases by 16% when using area of 2500mm2 of circular web openings shape (equal in area to square web opening size 50mm*50mm) and by 13.5% when using rhombus web openings shape of the dimensions 50*50mm in comparison with the case of 60-mm size square web openings.
In this paper an experimental works conducted to study the behavior of R.C. beam with large web opening at different locations and fortified with reactive powder composite (RPC) at the extreme tension zone (bottom edge of opening) and/or extreme compression zone (Top edge of opening). The experimental study is investigate the behavior of twelve beams and study the ability of using normal strength concrete together with RPC in the same section to exploit the advantages of these two materials in optimal way. The main variables are RPC layers locations in tension zone and/or in compression zone and the locations of openings. The ultimate loads, load mid-span deflection behavior and strain for steel and concrete were discussed. The experimental results showed that the ultimate strength was decreased with increasing number of opening about 4% for beams with two openings located in shear zone and 21% for beams with three openings, thus indicating that the stiffness decreases accordingly. The using RPC layers effectively enhanced performance of hybrid beams when compared with using the normal strength concrete layers only. The using RPC layers in compression and tension zones increased the ultimate load about 47 % for beams with two opening located in shear zone, when using RPC in the tension zone and normal strength concrete in the compression zone the ultimate flexural load and ultimate deflection increase little compared with normal concrete.
This study investigated numerically and experimentally fluid flow and heat transfer in the desktop PC. Three patterns of the positions of air inlet and outlet were tested to find the best one for cooling. The computer components in the present study are CPU, finned heat sink, power supply, motherboard, CD, HDD and fans. Three components which were generate heat are CPU, motherboard and power supply and there were two openings for air inlet and two for air outlet. The air inlet velocities were 1.2, 1.8, 2.4 m/s with constant CPU fan velocity. The studied parameters were the changed of inlet air velocity, powers of CPU, motherboard and PSU and the positions of inlet air. The numerical results obtained are found in a good agreement with the experimental results. The experimental results show that the maximum temperature was 81 at 16.5 W and 1.2 m/s. Numerical results showed that the CPU temperature reaches 89.6 at 18.5 W and 1.2 m/s. From the results, it was found that; the temperatures of the main components (PSU and motherboard) affected little by CPU power and vice versa, the finned heat sink has higher cooling efficiency and the pattern 1 was the best pattern for CPU cooling.
Openings in reinforced concrete (RC) slabs are usually created as a result of variations in construction function, architectural or mechanical necessities. Heavy equipment loads resulting from mechanical system of any building are often carried by RC slabs. Even the static analysis and design of RC slabs with opening is not clearly stated in the available international Codes, dynamic analytical solution for such structure is complex._x000D_ In this paper, numerical analysis based on finite element approach is utilized to implement the modal analysis of RC slabs. Opening size and position was parametrically studied. Slab natural frequency or periods in addition to, the mode shape were registered. The results showed that the opening size and position involved in RC slab had a significant change in the value of natural frequency and period for the high level modes. The material nonlinearity affect on free vibration analysis of RC opening slab with different levels of stiffness modifiers was taken into account. The dynamic characteristics of RC opening slab as a function of stiffness modifier degree was numerically measured for six mode shapes. The paper found that a reduction in stiffness modifier value greatly reduce the .natural frequency of RC opening slab.