الفهرس 
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Abstract
The following points can be advanced based on experiments performed on seven flat slabs, including the number of openings, the location, and the effect of different shear reinforcement schemes on the behaviour of punching shear. Two methods were used to compare the results of experiments done on seven reinforced concrete slabs with edge column connections. The first method involved performing a theoretical analysis using ANSYS v.21 program. The second method involved calculations using the code equations. Different parameters were examined. Three slabs of different sizes were studied for many different factors. These models investigate the negative effect of the opening on the resistance to punching shear in thin flat slabs with edge column connections. Then, another parameter was studied, which is the influence of varying the diameter of the studs on the punching shear resistance of flat slabs. studying the dimensions of the openings, their location, and the optimal positioning of two openings in the flat slabs. The optimal positions, numbers, diameters, and spacing between the shear-studs, as well as the number of rows, were analyzed.
6.2 Conclusion
from the experimental study conducted in the present investigation, the following conclusions may be drawn:
1.The presence of openings in a flat slab significantly reduces shear punching capacity and energy absorption.
2.Creating an opening at the column face and increasing the opening dimension to a value greater than span/10 (the limit of Egyptian code) shows a high DROP in punching shear resistance. Increasing opening numbers decreased ultimate failure, stiffness, and energy absorption.
3.Different shear reinforcement schemes (bent-bar, shear-band, and shear-studs) improve ultimate load, and energy absorption in slabs with one opening, effectively recovering the total lost strength compared with a slab without openings. The sheer-studs scheme is the best of them.
4.When shear studs were used in a slab with one opening, it was discovered that the first cracking load, ultimate load, and energy absorption increased by about 10%, 4%, and 104%, respectively. When shear band was used, the ratios were 5%, 3%, and 44.14%. when bent bar was used the ratios were 2.5%, 1%, and 28.12%; compared to the slab without openings and without shear reinforcement schemes.
5.Even though the flat slab with two openings had a nearly 50% smaller area than the control slab, the presence of shear studs greatly enhanced the punching shear behaviour, resulting in a maximum load capacity of 0.86 compared to the control slab.
The experimental results were compared to the analytical method (several codes), and the findings showed close similarity between them:
1.In conclusion, most equations from different codes (ACI, EC2, ECP-203, CSA-A23.3-04, NZS 3101.2006) gave reasonably accurate ultimate punching capacity findings for reinforced slabs with varying methods of reinforcement, matching experimental data. However, Eurocode 2 (EC2) equations significantly overestimated capacity. The EC2 equations’ consideration of the critical perimeter, 2d from the loaded area, may explain the difference.
The experimental results were compared to the numerical method (ANSYS v. 21):
1.The experimental results were compared to the numerical method (ANSYSv.21), and the findings showed close similarity. Theoretically, slabs without openings and reinforced with one of three different schemes increased ultimate shear resistance by 13% for shear studs and shear bands and 8% for bent bars.
2.It was found that the model with two openings and without shear-reinforcement schemes had a 42% reduction in ultimate punching capacity. However, when reinforced with shear studs, the decrease in ultimate load was just 13%.
3. The ultimate punching load capacity and cracking load decrease with an increase in the opening dimension.
4. For openings located at the column face, increasing the dimension of the opening to a value higher than the column dimension results in a significant decrease in punching shear capacity, with a DROP of approximately 29%. However, for openings of the same size located at the column corner, the reduction in capacity is only 20%.
5.After analyzing various slab dimensions, it was determined that openings should be placed in the column’s corner rather than on its face.
6.It is advised to place the two openings on horizontal corners if necessary. This arrangement minimizes the reduction in ultimate load capacity while maintaining the ductility of the flat slab.
7.For opening at the column corner with a dimension span/20 and with the same column dimension, the ultimate load increased by 8%, and for opening with a dimension span/10, the load increased by 25% more than the same opening at the column face.
8.Openings with Egyptian code limits span /20 and with the same column dimension at a distance (1.5 ts) from the column corner or column face decrease the slab ultimate load by only 2.2% to 5.6% respectively.
9.Three shear studs between 150mm and 200mm apart are the ideal space for shear studs in a box arrangement. As more rows increase, the shear resistance increases. The recommended distance between rows is 200mm. Additionally, shear resistance increases as shear stud’s diameter increases.
6.3 Recommendations for Future Research
The following recommendations are suggested for future numerical and experimental work.
1. Study the behavior and capacity of full-scale slab-column connections containing openings and shear reinforcements under lateral loading. This could bring further insight into the system-level performance beyond individual slab capacities.
2.Investigate novel strategies for reinforcing the slabs with openings to withstand punching shear failure.
3. Conduct further analytical and numerical studies to develop and validate accurate predictive models and design equations for the punching shear capacity of reinforced concrete slabs with openings and different shear reinforcement schemes. Refine existing code provisions based on new data.
4.Further evaluation and refinement of code provisions - Expanding the experimental database to improve and validate the accuracy of punching shear design equations in major codes for slabs with openings and shear reinforcements.
5.Long-term testing - Monitoring the shear reinforcement systems’ long-term durability and sustained load capacity through long duration structural testing.
6.Investigate size effects - does the punching shear behavior scale accurately from smaller slab slabs to full structural sizes? What implications does size have?