Journal of University of Babylon

The present paper describes dynamical behaviour of a uniformly curved beam of ‎tapered cross section under the action of periodical load. The investigated dynamics divided ‎into two main parts ; the first deals with the effect of the slope of taper on the natural ‎frequency. The second part studies the effect of the periodical load on the stability of the ‎beam. The effects of the value of the axial force and the total angle of curvature are ‎discussed. Also the effects of excitation parameter and the periodical force are shown through ‎graphs.‎

calculate the interfacial friction factor in annular flow has done. These data are conducted ‎from two different sources with same fluid through pipe: 5.08 cm diameter and 36 m length ‎with angles of inclination 0o, -5o, and -20o . The comparison reveals the performance of ‎Tsiklauri and Lee-Bankoff correlations are so converged but the correlation of Tsiklauri is ‎the best performance.‎

The great importance of composite materials in recent years is resulted from their ‎desired properties so, these materials have different engineering applications.‎
In this paper, study of thermal conductivity of polymer matrix composites where ‎high density polyethylene is used as matrix material which is particulated reinforced ‎with silicon carbide, silicon oxide, magnesia, asbestos and with kaolin, has been done. ‎All specimens are perpetrated by press molding technique using tool steel die and ‎hand-pressing machine with 20.3 Mpa with heating up to 100 C for 20 minutes and ‎without heating for 15 minutes in the weight percent (0,5,10,15,20,25) from each filler ‎materials.‎
‎ Thermal conductivity coefficient is calculated for each specimens. one of the ‎obtained results show that specimen reinforced with 25% asbestos has lower thermal ‎conductivity coefficient value comparison with the other additives.‎

In reinforced concrete construction, discontinuity of reinforcing bars is often ‎encountered even within length of a single member. Lap splices are preferred means ‎for providing continuity of reinforcing bars because of their practical and economical ‎characteristics. Hence, extensive experiments and limited number of analytical studies ‎have been implemented in this field to clear-up performance characteristics. In this ‎paper, the modulus of displacement theory is adopted to analyze the local behavior of ‎tensile reinforcement lap splices. Both compatibility and equilibrium conditions are ‎utilized to determine the distribution of steel and bond stresses of the reinforcing bars ‎along the lap region‏.‏
The equations derived herein and the general form for distribution of stresses, ‎are quite consistent with the analytical and experimental observations of numerous ‎researchers in this field. The analytical results confirmed that bond deterioration occur ‎simultaneously from both ends of the lap splice toward its center. Also, the numerical ‎examples implemented herein give reasonable agreement between the analytical and ‎experimental results‏.‏

A one-dimensional finite element model for predicting the behavior of deformed ‎bars embedded in concrete is developed. In this model, the bond between steel and ‎concrete is simulated with discrete springs that connect the bar to concrete along the ‎anchorage length, whereas the reinforcing bar is subdivided into axial elements. This ‎technique involves the construction of the total tangent stiffness matrix of the ‎anchorage for use in an incremental solution algorithm of the nonlinear problem.‎
The proposed model is used for simulating the behavior of bonded bar with ‎common types, such as the anchored bars in beam-column connections and spliced ‎bars of the reinforcement lap splices. The analytical results are compared with ‎available results of pull- out and flexural tests, and suitable agreement is found.‎

In the present work a formulation of equation of state (EoS) was used to evaluation ‎the phase equilibrium ratios. ‎
‎ Two constant Equation of state, such as the Piench Ropenson, Soave modification ‎of the Redlich Kwong equation can not be highly accurate in the whole range of ‎temperature, pressure, and composition, but they have the advantage that they require ‎relatively little computer time and Soave Redlich Kwong (SRK) equation seldom ‎gives rise to large errors when its applied to mixtures of lower hydrocarbon, nitrogen, ‎carbon monoxide, carbon dioxide, and hydrogen sulphide.‎
‎ Vapor-liquid equilibrium calculations were run on PC using QuickBasic V4.5 ‎language.‎
‎ The Soav Redlich Kwong Equation is stated in a form particularly useful for ‎computer applications of complex and undefined mixtures calculations, such as crude ‎oil and petroleum fractions.‎

An experimental study was conducted to investigate the impact resistance of ‎concrete reinforced with steel fibers (SFRC) and waste flax fibers (WFFRC). The ‎impact strength was measured by using a simple, portable and practical drop-weight ‎test recommended by the ACI Committee 544. Other mechanical properties including ‎compressive strength, splitting tensile strength and modulus of rupture were also ‎examined. Variables incorporated in this research were fiber type, fiber content, ‎compressive strength and age of testing. Steel fibers and waste flax fibers were added ‎to concrete in various volume fractions of up to 1 and 4% respectively.‎
The fiber reinforced concrete (FRC) investigated is superior in impact strength ‎to the plain control concrete. This property increases as the amount of fibers addition ‎is increased. When the observed values are compared, the 4% volume fraction of ‎waste flax fibers can produce impact strength comparable or higher than that obtained ‎at 1% crimped steel fibers. For a given steel fiber content, the impact strength ‎increases with matrix compressive strength up to a certain limit beyond which it starts ‎to decrease. The capacity of WFFRC to absorb impact energy enhances as the ‎compressive strength of the matrix and the age increase.‎
The analysis of the test results also shows that compressive strength, splitting ‎tensile strength and modulus of rupture are improved by including crimped steel ‎fibers, but insignificantly influenced by waste flax fibers.‎

This investigation was carried out to study the effects of fibre reinforced ‎concrete on compressive strength, tensile strength, shrinkage, tensile strain capacity, ‎crack width, and cracking time of concrete.‎
Laboratory tests were made on end-restrained plain and fibre reinforced ‎concrete beams and by using specimens cubs (150mm) and cylinders (100*200mm). ‎Two types of fibres were used and their volume fraction ranged from 0.25% to 2%.‎

Based on the results of this work, it was found that the compressive strength ‎decreases with increasing fibre content for both types of fibre, but the maximum ‎compressive strength and splitting tensile strength at 1.5% crimped fibre content.‎

The test results showed that fibre addition decreases shrinkage of concrete ‎significantly. It also reduces crack width. It was also found that tensile strain capacity ‎decreases and cracking time increases with fibre addition. The magnitude of the ‎charge in properties, however, depends on the type of fibre used.‎