The modern electric utility industry is currently more and more attention to HVDC transmission as a practical alternative to HVAC transmission. It is useful supplement to rapid and smooth power flow control, more economical choice and small power loss for long transmission systems. An electric power system with DC links requires a special analysis for power flow study that takes their characteristics into account. This paper presents an AC-DC load flow algorithm to solve a power flow problem with DC links. This algorithm is tested using medium and long transmission standard test systems. Digital results using the proposed sequential method are compared w ith a previous work. The effect of load change in HVDC control parameters is studied. A comparison between HVAC and HVDC transmission systems based on power losses are also performed.

Bond characteristics have been investigated of cylindrical specimens with epoxy coated and uncoated bars under different ambient conditions. Forty six pull-out test carried cut on cylindrical specimens of 15 cm diameter and 30cm height with mild steel and deformed tensile steel bars. some of them were tested after exposed to temperature between 50 and 400O. Thickness of the epoxy coating film and grade of both concrete and steel were taken as variables. The results showed that both bond strength and free end slip are largely affected by both ambient temperature and thickness of the coated film.

This work is a development of constitutive model for concrete by the theory of plasticity at high temperature. In this model, non-uniform work hardening plasticity model adopts the most sophisticated failure model of Willam - Warnke five-parameter model. This model was modified to include the effect of the temperature on concrete structures. The developed model can predict the effect of the fire on concrete structures at diffirent types of temperature loading from room temperature to very high temperature

This work is a development of constitutive model for concrete by the theory of plasticity at high temperature. In this model, non-uniform work hardening plasticity model adopts the most sophisticated failure model of Willam - Warnke five-parameter model. This model was modified to include the effect of the temperature on concrete structures. The developed model can predict the effect of the fire on concrete structures at diffirent types of temperature loading from room temperature to very high temperature

This work is a development of constitutive model for concrete by the theory of plasticity at high temperature. In this model, non-uniform work hardening plasticity model adopts the most sophisticated failure model of Willam - Warnke five-parameter model. This model was modified to include the effect of the temperature on concrete structures. The developed model can predict the effect of the fire on concrete structures at diffirent types of temperature loading from room temperature to very high temperature

During field observation of some existing structures it was noticed that the unsymmetrical arrangement of longitudna1 reinforcement about the vertical axis of R.C. beam cross section has become a human problem. This problem is caused either due to a human error or an initial imperfections especially in marginally engineered non supervised structures. f t may also occur as a result of steel bar tutting in one side during electric works. The objective of t.his paper is from one hand to study the behavior of such beams, from the other hand to declare and drawback these errors. Experimental work was done in the R.C. laboratory, civil engineering department, Assiut university. Fourteen of the specified r.c. beams were tested under two point static loading up to failure. The effect of localization of both bottom and top reinforcement, quality of concrete, shear span to depth ratio as well- as the percentage of longitudinal reinforcement were studied. The cracking load, ultimate load, deflection and longitudinal strains were measured at mid span point on both sides oi the beams. Also, the pattern of cracks and mode of failure were also included in this study. A new recommendations were given concerning the drawbacks of these errors and its significance in practice

During field observation of some existing structures it was noticed that the unsymmetrical arrangement of longitudna1 reinforcement about the vertical axis of R.C. beam cross section has become a human problem. This problem is caused either due to a human error or an initial imperfections especially in marginally engineered non supervised structures. f t may also occur as a result of steel bar tutting in one side during electric works. The objective of t.his paper is from one hand to study the behavior of such beams, from the other hand to declare and drawback these errors. Experimental work was done in the R.C. laboratory, civil engineering department, Assiut university. Fourteen of the specified r.c. beams were tested under two point static loading up to failure. The effect of localization of both bottom and top reinforcement, quality of concrete, shear span to depth ratio as well- as the percentage of longitudinal reinforcement were studied. The cracking load, ultimate load, deflection and longitudinal strains were measured at mid span point on both sides oi the beams. Also, the pattern of cracks and mode of failure were also included in this study. A new recommendations were given concerning the drawbacks of these errors and its significance in practice

During field observation of some existing structures it was noticed that the unsymmetrical arrangement of longitudna1 reinforcement about the vertical axis of R.C. beam cross section has become a human problem. This problem is caused either due to a human error or an initial imperfections especially in marginally engineered non supervised structures. f t may also occur as a result of steel bar tutting in one side during electric works. The objective of t.his paper is from one hand to study the behavior of such beams, from the other hand to declare and drawback these errors. Experimental work was done in the R.C. laboratory, civil engineering department, Assiut university. Fourteen of the specified r.c. beams were tested under two point static loading up to failure. The effect of localization of both bottom and top reinforcement, quality of concrete, shear span to depth ratio as well- as the percentage of longitudinal reinforcement were studied. The cracking load, ultimate load, deflection and longitudinal strains were measured at mid span point on both sides oi the beams. Also, the pattern of cracks and mode of failure were also included in this study. A new recommendations were given concerning the drawbacks of these errors and its significance in practice

This work is a development of constitutive model for concrete by the theory of plasticity. In this model, non-uniform work hardening plasticity model adopts the most sophisticated failure model of Hsieh-Chen as a bounding surface by assuming an initial yield surface with a shape that is different from the failure surface; proposing a non-uniform hardening rule for the subsequent loading surfaces with a hydro static pressure and lode-angle dependent and utilizing a non-associated flow rule for a general formulation.

This work is a development of constitutive model for concrete by the theory of plasticity. In this model, non-uniform work hardening plasticity model adopts the most sophisticated failure model of Hsieh-Chen as a bounding surface by assuming an initial yield surface with a shape that is different from the failure surface; proposing a non-uniform hardening rule for the subsequent loading surfaces with a hydro static pressure and lode-angle dependent and utilizing a non-associated flow rule for a general formulation.