Concrete columns have an important function in the structural concept of many structures. Often, these columns are vulnerable to exceptional loads (such as impact, explosion or seismic loads) , load increase ( increasing use or change of function of structures, etc.) and degradation ( corrosion of steel reinforcement, alkali silica reaction , etc.). On the other hand, confinement of concrete is an efficient technique to enhance the structural behavior of concrete members primarily subjected to compression .Structural repair and rehabilitation of reinforced concrete structures is becoming an increasing important option for all deteriorated / damaged structures to restore, enhance the load bearing capacity and increase the life span of the structure. The strengthening of concrete structures with externally bonded reinforcement is generally done using either steel plates or FRP laminates. The main disadvantages of using steel plates are steel corrosion in the adhesion zone, heavy weight and excessive size of single plates. With the development of technology , the use of high- strength concrete members has proved most popular in terms of economy, superior strength , stiffness, and durability. With the increase of concrete strength, the ultimate strength of the columns increases, but a relatively more brittle failure occurs. The lack of ductility of high strength concrete results in sudden failure without warning, which is a serious drawback. [1] .The application of FRP in the construction industry can eliminate some unwanted properties of high strength concrete , such as its brittle behavior [2,3]. To study the behavior of normal and high strength circular R.C.columns confined with CFRP under statically load, tests on columns wrapped with FRP have been executed. The efficiency of externally bonded CFRP of circular R.C.columnsis declared and evaluated .

The safe operations at longwall face depend on the type and capacity of the powered roof supports. At Abu-Tartur longwall phosphate mine, two types of powered roof support with various capacities were tried earlier. The two leg shield power supports was applied finally. The main problem at Abu-Tartur longwall mines is the high frequency of roof rock falls during face advance. Roof collapse is due to an inadequate capacity of the chosen powered supports. So, in this paper the load exerted on the shield support is calculated by different methods and taking into consideration the actual roof conditions by rock mass classification system to select the suitable type of the supports. From these calculations, it is found that the average maximum pressure on the supports is about 416t/m with the yield pressure on the shield support of a value of 520t/m. Different items are recommended such as; increase the rate of the advance, exploit ore in two consecutive shifts, decrease the period of the face stoppage and small thickness about 30cm from phosphate ore should be left in the roof during exploitation to ensure stability during face advance. The following shearer is recommended to increase rate of face advance. The specification of this shearer are model Cat EL 3000/2011with typical length 15.2 m, seam thickness range from 2.5 to 5.5 m, cutting drum diameter up to 2.7 m, haulage speed up to 32 m per min, cutting drum speed 54.3 rpm and bits drum hardness up to 68.4 Mpa is to secure high rate of face advance. Shield support model Kottadih, CDFI,France, 2x470 is selected for Abu Tartur mining conditions to support the face during working.

The safe operations at longwall face depend on the type and capacity of the powered roof supports. At Abu-Tartur longwall phosphate mine, two types of powered roof support with various capacities were tried earlier. The two leg shield power supports was applied finally. The main problem at Abu-Tartur longwall mines is the high frequency of roof rock falls during face advance. Roof collapse is due to an inadequate capacity of the chosen powered supports. So, in this paper the load exerted on the shield support is calculated by different methods and taking into consideration the actual roof conditions by rock mass classification system to select the suitable type of the supports. From these calculations, it is found that the average maximum pressure on the supports is about 416t/m with the yield pressure on the shield support of a value of 520t/m. Different items are recommended such as; increase the rate of the advance, exploit ore in two consecutive shifts, decrease the period of the face stoppage and small thickness about 30cm from phosphate ore should be left in the roof during exploitation to ensure stability during face advance. The following shearer is recommended to increase rate of face advance. The specification of this shearer are model Cat EL 3000/2011with typical length 15.2 m, seam thickness range from 2.5 to 5.5 m, cutting drum diameter up to 2.7 m, haulage speed up to 32 m per min, cutting drum speed 54.3 rpm and bits drum hardness up to 68.4 Mpa is to secure high rate of face advance. Shield support model Kottadih, CDFI,France, 2x470 is selected for Abu Tartur mining conditions to support the face during working.

The safe operations at longwall face depend on the type and capacity of the powered roof supports. At Abu-Tartur longwall phosphate mine, two types of powered roof support with various capacities were tried earlier. The two leg shield power supports was applied finally. The main problem at Abu-Tartur longwall mines is the high frequency of roof rock falls during face advance. Roof collapse is due to an inadequate capacity of the chosen powered supports. So, in this paper the load exerted on the shield support is calculated by different methods and taking into consideration the actual roof conditions by rock mass classification system to select the suitable type of the supports. From these calculations, it is found that the average maximum pressure on the supports is about 416t/m with the yield pressure on the shield support of a value of 520t/m. Different items are recommended such as; increase the rate of the advance, exploit ore in two consecutive shifts, decrease the period of the face stoppage and small thickness about 30cm from phosphate ore should be left in the roof during exploitation to ensure stability during face advance. The following shearer is recommended to increase rate of face advance. The specification of this shearer are model Cat EL 3000/2011with typical length 15.2 m, seam thickness range from 2.5 to 5.5 m, cutting drum diameter up to 2.7 m, haulage speed up to 32 m per min, cutting drum speed 54.3 rpm and bits drum hardness up to 68.4 Mpa is to secure high rate of face advance. Shield support model Kottadih, CDFI,France, 2x470 is selected for Abu Tartur mining conditions to support the face during working.

The effect of anchor embedded length and impact load on the mechanical properties of adhesive concrete joint under different dynamic loading rate was studied [1]. Hopkinson pressure bar was used to apply dynamic load to specimens. Specimens with through hole and embedded anchor lengths of 2.5 cm and 5 cm were used in the study. The specimens were hit with strain wave induced using air pressure of 1 and 1.5 bar respectively. The result showed that as the embedded length decrease the maximum load of failure increase also as the pressure increase the specimen tend to absorb most of the wave in the adhesive joint. While as the load wave magnitude decrease the portion of the wave transmits to the concrete part of the specimen causing rupture or cracking of this part increase.

The effect of anchor embedded length and impact load on the mechanical properties of adhesive concrete joint under different dynamic loading rate was studied [1]. Hopkinson pressure bar was used to apply dynamic load to specimens. Specimens with through hole and embedded anchor lengths of 2.5 cm and 5 cm were used in the study. The specimens were hit with strain wave induced using air pressure of 1 and 1.5 bar respectively. The result showed that as the embedded length decrease the maximum load of failure increase also as the pressure increase the specimen tend to absorb most of the wave in the adhesive joint. While as the load wave magnitude decrease the portion of the wave transmits to the concrete part of the specimen causing rupture or cracking of this part increase.

The effect of anchor embedded length and impact load on the mechanical properties of adhesive concrete joint under different dynamic loading rate was studied [1]. Hopkinson pressure bar was used to apply dynamic load to specimens. Specimens with through hole and embedded anchor lengths of 2.5 cm and 5 cm were used in the study. The specimens were hit with strain wave induced using air pressure of 1 and 1.5 bar respectively. The result showed that as the embedded length decrease the maximum load of failure increase also as the pressure increase the specimen tend to absorb most of the wave in the adhesive joint. While as the load wave magnitude decrease the portion of the wave transmits to the concrete part of the specimen causing rupture or cracking of this part increase.

This paper introduces a new technique for deep drawing of elliptic cups through a conical die without blank holder or draw beads. In this technique an elliptical-cup is produced by pushing a circular blank using a flat-headed elliptic punch through a conical die with an elliptic aperture in a single stroke. A 3D parametric finite element (FE) model was built using the commercial FE package ANSYS/APDL. Effects of die and punch geometry including, half-cone angle, die fillet radius, die aperture length and punch fillet radius on limiting drawing ratio (LDR), drawing load and thickness strain of the cup have been investigated. A die with half cone angle of 18° has shown the best drawability for the new technique. Finite element model results showed good agreement with experimental results. A die with an aspect ratio of 2 has been used with punches having aspect ratios ranging from 2 to 2.25. Tensile tests were carried out to obtain the stress-strain behavior for the used material. A total of seven punches were used for forming sheet metal of brass (CuZn33) with initial thicknesses of 1.5, 1.9, 2.4 and 3.2 mm at different clearance ratios (c/t). The effects of blank thickness and clearance ratio on limiting drawing ratio, drawing load and thickness strain were experimentally investigated. An elliptic cup with a limiting drawing ratio (LDR) of 2.26 has been successfully achieved.

This paper introduces a new technique for deep drawing of elliptic cups through a conical die without blank holder or draw beads. In this technique an elliptical-cup is produced by pushing a circular blank using a flat-headed elliptic punch through a conical die with an elliptic aperture in a single stroke. A 3D parametric finite element (FE) model was built using the commercial FE package ANSYS/APDL. Effects of die and punch geometry including, half-cone angle, die fillet radius, die aperture length and punch fillet radius on limiting drawing ratio (LDR), drawing load and thickness strain of the cup have been investigated. A die with half cone angle of 18° has shown the best drawability for the new technique. Finite element model results showed good agreement with experimental results. A die with an aspect ratio of 2 has been used with punches having aspect ratios ranging from 2 to 2.25. Tensile tests were carried out to obtain the stress-strain behavior for the used material. A total of seven punches were used for forming sheet metal of brass (CuZn33) with initial thicknesses of 1.5, 1.9, 2.4 and 3.2 mm at different clearance ratios (c/t). The effects of blank thickness and clearance ratio on limiting drawing ratio, drawing load and thickness strain were experimentally investigated. An elliptic cup with a limiting drawing ratio (LDR) of 2.26 has been successfully achieved.

Fatigue behaviour of rubber is a very important characteristic due to its extensive use in many engineering applications. In most applications, rubber is commonly subjected to fluctuating loads, which often lead to failure due to the nucleation and growth of defects or cracks. Due to their viscoelastic behavior, rubbers have a high damping ability. Very often rubbers are subjected to different frequencies in the service, such as engine mounts. The effect of frequency on the fatigue lifetime needs deep investigations. In present work, the effect of frequency on the styrene butadiene (SBR) and nitrile-butadiene rubber (NBR) with 0,20,30,50 and 70 Phr of carbon black was investigated. It was found that the fatigue lifetime decreased with the increase of the frequency. Increasing carbon black (CB) contents in rubber improved the fatigue resistant and increased of the fatigue lifetime.