SOME PARAMETERS AFFECTING THE STATIC BEHAVIOR OF NORMAL STRENGTH RECTANGULAR R.C. SHORT COLUMNS CONFINED BY CFRP

This paper describes a theoretical study of the effect of both acting axial loads and grade of concrete on the static behaviour of (32) thirty two Reinforced Concrete (RC) Beam-column joints. ABAQUS\CAE version 6.7, a nonlinear finite element analysis software package, was developed specifically for the analysis of reinforced concrete structures under plane stress conditions. Variable axial loads were applied and increased gradually with constant lateral load, which was applied maintaining at the top of the column at internal and external beam-column joint only the ultimate and cracking axial loads were recorded as well as the corresponding versus vertical displacement, the maximum joint shear stresses, axial, stresses strains, and absorbed energy, mode of failure using different grades of concrete C250, C400, C600 and C1200 were evaluated and recorded.

This paper describes a theoretical study of the effect of both acting axial loads and grade of concrete on the static behaviour of (32) thirty two Reinforced Concrete (RC) Beam-column joints. ABAQUS\CAE version 6.7, a nonlinear finite element analysis software package, was developed specifically for the analysis of reinforced concrete structures under plane stress conditions. Variable axial loads were applied and increased gradually with constant lateral load, which was applied maintaining at the top of the column at internal and external beam-column joint only the ultimate and cracking axial loads were recorded as well as the corresponding versus vertical displacement, the maximum joint shear stresses, axial, stresses strains, and absorbed energy, mode of failure using different grades of concrete C250, C400, C600 and C1200 were evaluated and recorded.

The behavior of the strip footing on sand was deeply studied in many publications. They were trying to improve this behavior through many techniques. These improvements include the using of geogrid and geotextile reinforcement, skirts on the sides of the footing to elongate the contact surface of the footing with soil. None of these studies had implemented in the effect of the contact shape of the footing on its behavior. In this present experimental study, it is intended to observe the behavior of the convex strip footing on sand with different strip footing contact shapes. A series of experiments using different convex strip footing contact shapes, are carried out on sandy soil. The results showed that the increase in the strip footing contact areas, did not increase the bearing capacity, but decreases the ultimate bearing capacity load from about 30% to 60%. Also with sever convex curve, the ultimate load decreases seriously.

Rock mass classification systems consider one of the design tools, which are used in conjunction with engineering assessments and other design approaches. There are many classification systems, which are widely employed in rock engineering. In this study one of these systems is used for the selection of the optimum panel width in phosphate mine Abu Tartur area. Geological Strength Index (GSI) is one of these systems which enables for calculations of the panel width. Data for the GSI system are obtained from geological reports, some field measurements and laboratory tests. The obtained panel width (wall length) for Abu-Tartur area is calculated to be about 100m (102m) which differs strongly from the applied length in the area (150m). So, it is recommended to apply this obtained length to secure safe mining conditions without roof falls which is the main problem facing underground mining in this area.

Rock mass classification systems consider one of the design tools, which are used in conjunction with engineering assessments and other design approaches. There are many classification systems, which are widely employed in rock engineering. In this study one of these systems is used for the selection of the optimum panel width in phosphate mine Abu Tartur area. Geological Strength Index (GSI) is one of these systems which enables for calculations of the panel width. Data for the GSI system are obtained from geological reports, some field measurements and laboratory tests. The obtained panel width (wall length) for Abu-Tartur area is calculated to be about 100m (102m) which differs strongly from the applied length in the area (150m). So, it is recommended to apply this obtained length to secure safe mining conditions without roof falls which is the main problem facing underground mining in this area.

Rock mass classification systems consider one of the design tools, which are used in conjunction with engineering assessments and other design approaches. There are many classification systems, which are widely employed in rock engineering. In this study one of these systems is used for the selection of the optimum panel width in phosphate mine Abu Tartur area. Geological Strength Index (GSI) is one of these systems which enables for calculations of the panel width. Data for the GSI system are obtained from geological reports, some field measurements and laboratory tests. The obtained panel width (wall length) for Abu-Tartur area is calculated to be about 100m (102m) which differs strongly from the applied length in the area (150m). So, it is recommended to apply this obtained length to secure safe mining conditions without roof falls which is the main problem facing underground mining in this area.

This paper presents a comparative experimental study on the performance characteristics of the circulating air coolers for the generators of the hydro-power plant of the High Dam in Aswan. The study considers two different air-water cooler designs of cross flow finned tubes heat exchangers working under varying operating conditions. The circulating air temperatures and the cooling water pressures for twelve coolers in each of the twelve units of the hydro-power plant were measured and analyzed to obtain useful results describing the cooler performance. The experimental results are based on measurements over total time duration of 1008 operating hours covering 42 summer days. The results are discussed to investigate the effects of time variation of the generated power, and the locations of the coolers and the power units on the performance of both cooler designs. The results of the actual fouling factor indicate that both coolers were designed with excess surface area to work well for long periods. The agreement of the experimental results with the commonly used effectiveness empirical relation indicates the proper performance of the working coolers. On the other hand, the discussion of the results showed the malfunction of some coolers due to the blockage of their damaged tubes. The overall performance of the air coolers in most power units of the plant maintains good flow behaviour of the hot air and uniformity of its temperature at levels sufficiently below the normal design temperature range for the generators of most power units.

Modeling and simulation of production lines is considered to be important for designers who are interested in: Work-load Allocation Problem (WAP), Server Allocation Problem (SAP), and Buffer Allocation Problem (BAP). This paper studies and analyzes a real cement production line as a case study. A simulation model is developed by ARENA software and used to analyze and test several bottlenecks that are causing severe congestions in different areas on the production line and could resolve all of these bottlenecks. Workstation failure data is collected along one year to obtain the machines failure behaviors. This paper searches for the optimum buffer sizes with the increase of the production rate. An actual cement production line is studied and analyzed by the simulation model from stem to stern. After a simulation replication time of 12 days, a simulation results show the line bottlenecks, workstations utilization, buffer capacities and the line production rate. To resolve the bottlenecks, a redesign of allocation of buffers which verify an optimum size could be made and it might be taken into consideration when designers implement this line. Finally modified optimum workstations utilization, buffer capacities and the line production rate with an increase about more than 15% of the production rate and economizing of 34 % of buffer capacities.

Modeling and simulation of production lines is considered to be important for designers who are interested in: Work-load Allocation Problem (WAP), Server Allocation Problem (SAP), and Buffer Allocation Problem (BAP). This paper studies and analyzes a real cement production line as a case study. A simulation model is developed by ARENA software and used to analyze and test several bottlenecks that are causing severe congestions in different areas on the production line and could resolve all of these bottlenecks. Workstation failure data is collected along one year to obtain the machines failure behaviors. This paper searches for the optimum buffer sizes with the increase of the production rate. An actual cement production line is studied and analyzed by the simulation model from stem to stern. After a simulation replication time of 12 days, a simulation results show the line bottlenecks, workstations utilization, buffer capacities and the line production rate. To resolve the bottlenecks, a redesign of allocation of buffers which verify an optimum size could be made and it might be taken into consideration when designers implement this line. Finally modified optimum workstations utilization, buffer capacities and the line production rate with an increase about more than 15% of the production rate and economizing of 34 % of buffer capacities.