الفهرس 
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Abstract
The use of high-strength concrete (HSC) in reinforced concrete structures is becoming popular in all over the world. HSC became more available even under site conditions because of the great development of construction industry. Concrete technology has developed and now concrete strength of 100 Mpa or higher can be reached without difficulties.The experimental work presented in this study was undertaken to investigate the ultimate punching shear response of HSC reinforced concrete slab. The experimental program consisted of fourteen slab specimens of square shape, each with a column stub at its center. The test specimens were intended to simulate a half scale interior-slab-column connection. All slabs were reinforced with identical longitudinal steel bars. The tested slabs were divided into five series according to test parameters. The parameters investigated include eccentricity of the applied load, type of shear reinforcement, openings, and slab thickness. All specimens were tested as simply supported slabs under one point static loading. The load was applied as a static load.
A comparison established between the experimental and the analytical results obtained from applying the punching shear strength formulae given in design codes, and non-linear finite element analysis; NLFEA. A total of five building codes were examined with regard to their provisions concerning the punching shear. ANSYS 5.4 software package was used for non-linear analysis.For all slabs load eccentricity had a noticeable effect on the mode of failure and ductility of HSC flat slabs. Specimens tested under eccentric loading showed more ductile behavior than specimens tested under centric loading. The ultimate load of test specimens decreased as the moment transferred to the column increased. The reduction in the ultimate loads for the specimens without openings or shear reinforcement compared with the concentrically loaded specimen was ranging between 12.0% and 33.0%. The ultimate loads were increased with the addition of bent-up bars as shear reinforcement particularly in case of eccentric loading. An increase in the ultimate load ranging between 9% and 39% was recorded for a load eccentricity of 0.15m and 0.225m, respectively. Comparable behavior was achieved for specimens provided with vertical stirrups. The increase in the ultimate load for specimens with stirrups was 17%, and 41%, compared to test slabs without shear reinforcement. The presence of opening resulted in a decrease in the ultimate load of the test specimens especially in case of eccentrically loaded specimen .The ultimate load of specimens without openings was larger than the ultimate loads of specimens with openings by 7%, 50% and 127%, for 0.0m , 0.15m and 0.225m load eccentricity, respectively. The reduction in the ultimate loads for the specimens with openings tested under eccentric load was from 37.0% to 69.0%, with respect to that of the specimen with opening under centric load. The slabs thickness has a noticeable effect on the punching shear capacity. An increase of 37% and 150% in the shear capacity was recorded by increasing the slab thickness from 100 mm to 130mm and 160mm, respectively. Codes comparison indicates a significant variation in the punching shear predictions from code to another. The ECCS shows the most conservative prediction for punching shear capacity specially in case of using shear reinforcement as the code provisions neglect the effect of shear reinforcement. The mean predicted-to-experimental ultimate load is shown to be 0.45. The predictions following the BS and EC2 are closet to the experimental results. The mean predicted-to-experimental ultimate load is shown to be 0.69 and 0.81 for BS and EC2, respectively. The superiority of the predictions attributed to the wide perimeter of critical punching shear sections adopted in the BS and EC2 codes. The ACI and CSA provisions for punching shear analysis are shown to be conservative. The mean predicted-to-experimental ultimate load is shown to be 0.50 and 0.61, respectively. To the range of the test parameters investigated, the application of non-linear finite element analysis using ANSYS 5.4 package yielded satisfactory load-carrying capacities, and acceptable cracking loads and load-deflection responses.