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There are a lot of engineering structures working at elevated temperatures for long periods, as in chemical plants, generation, transfer and energy application or devices uses of energy, such as turbines and reactors. When those parts work at high temperature, it was found that their materials which exposed to loads will undergo to plastic deformation and deforms slowly like a crawl turtle, for this reason they named this slow deformation as a Creep. Care has been given in this research has to study the issue of creep under the influence of various loads under certain temperature, and the implementation of a creep test machine by a tension samples made from lead .This research includes a study of creep parameters under the influence of temperatures. Creep properties were investigated under constant stress and fixed temperature in terms of the relation between a strain for period of times by the specimen used in this study which was lead and the applied load was tension.

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The work describes a research study the creep behavior of a gypsiferous soil, the soil used throughout this study was taken from location of Tikrit University site in Salah El-Deen City in Iraq. The soil was clayey sand and classified as (SC) according USCS with a gypsum content of (48.92%). The mineralogical and chemical properties of the soils were determined. The Odometer test was used throughout the test programs. A series of double and single oedometer tests for a long period time were performed in this work . The results indicate that the soil is of low compressibility when loaded under drying condition for both 1day and 64 day respectively while high compressibility it can be noticed for wet soil sample under the same loading period. The collapse potential increases with logarithm of time noticed for 200 kPa stress (8.17% at 1day to 16.17% at 64 days) and (12.2% at 1 day to 14.7% at 64 day) for 1600 kPa stress. The results showed that the increases in collapse potential with the increasing applied stress for the samples loading for 1 and 64 day, also it can be observed high decrease in collapse potential (21.2 % to 14.7 %) after 800 kPa stress for 64 day loading sample. Also the results show nonlinear relations between the creep rate and logarithm of time, the creep rate decrease about (4.4% and 2.5 %) from 1day to 64 day for 200 and 1600 kPa stress respectively.

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The present work is a theoretical macro mechanics study, which concentrates on linear viscoelastic creep behavior of short fiber reinforced polymeric compositematerials to estimate their flexural creep modulus at constant room temperature and ata time range of 1 to 109 seconds. The loading cases are concentrated and thedeformations have been limited with small strains without permanent deformation. Athree-parameter model is used as a mathematical viscoelastic model. A finite elementprogram in Quick Basic had been designed to obtain the flexural creep modulus. Halpin-Tsai equation shows an improvement in the modulus values for compositematerials reinforced with short fibers in both aligned and random reinforcementthrough flexural creep estimations. On the other hand, the modified rule of mixturesshows a slight effect of reinforcement on this property. 56789ا:

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The nonlinear thermoviscoelastic behavior of composite thin plate from polyester reinforced with random fiber glass was investigated. The hereditary elasticity (viscoelastic) behavior described in new mathematical model predicted from experimental data from creep and relaxation tests to predict the creep compliance and relaxation modulus equations then apply that mathematical model in numerical and analytical analysis to describe the nonlinear viscoelastic behavior of thin composite plates at different loading and temperatures. The creep specimens and composite thin plate have the same volume fraction. A very good agreement has been found between experimental, theoretical and FEM method. It is found that the deflection increases with approximate rate (50 %) at time (15 min.) and the shear stress (xy) increases with approximate rate (58%) at time (30 min.), as a result of increasing the distributed load (q=1.934e-3 N/mm2 to q=3.4488e-3 N/mm2) at temperature (30 Co) of relative dimension (a/b=0.5) and rectangular simply support plate. The increasing temperature from (30 Co- 60 Co) increases the deflection with approximate rate (34.6%).

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Background and objective: Staphylococcus aureus (S. aureus) is responsible for a wide range of diseases and increased number of the strains that acquired resistance to antibiotics. The emergence of Vancomycin resistance of S. aureus has been a significant impact on human health. The distribution of Vancomycin minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) in S. aureus isolates, and compared antibiotic susceptibility to non-glycopeptideantibiotics in different Vancomycin MIC value groupswere assessed in this study.Methods: S. aureuswere isolated by standard method and subjected to MIC tested by broth microdilution method for Vancomycin and eight non-glycopeptideantibiotics, alsoVancomycin MBCs were determined.Results: Approximately 56% of S. aureus with a 0.5 µg/ml Vancomycin MIC were accounted, whereas 1.77% of S. aureushadan 8 µg/ml Vancomycin MIC. In other hand, most S. aureus had 1 and 2 µg/ml Vancomycin MBC.Conclusion: About half of the S. aureus isolates had 0.5 µg/ml of Vancomycin MIC. Relationship between Vancomycin MIC and resistance to non-glycopeptideantibiotics were observed, with increased Vancomycin MIC, the resistance to others antibiotics also elevated, and vice versa.

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The nonlinear thermoviscoelastic behavior of composite thin plates isinvestigated. An experimental program covers an achievement of creep tests under different temperatures, dimensions of specimens and distribution loads to describe the equation of creep compliance. The stress relaxation is also determined from the experimental creep compliance. A new equation of creep compliance function D(ts, ,T) and relaxation modulus E(t,e,T) were predicted from the experimental results to describe the nonlinear thermoviscoelastic behavior of composite thin plates. A good agreement has been observed between the proposed models of nonlinear behavior at different temperatures and experimental results and between both theoretical and FEM results.It was found that thus the deflection is increasing at the beginning and the rate of increase is nearly constant and increase with increasing temperature from 30 Co to 60 Co with approximate rate (34.6%) for simply support plate at distributed load (q=1.934E-3 N/mm2), relative dimensions (a/b)=1.0 and time=15 min.The results indicate that the shear stress increases with rate (50.7%), so that strain in y-axis increases with rate (19%) as a result of increase the temperature from (30 Co to 60 Co).

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The study aims to present new form to calculate the long-term deflections (time dependent) for reinforced concrete beams (normal & high strength).The presented form taking into account the effect of several factors such compressive strength of concrete, the reinforcement at compressive zone, cross section dimensions, and span length. The results of the presented form were compared with experimental results of other researchers, and a good agreement was obtained. Among the conclusions drawn, the long-term deflections are highly reduced by increasing the compressive strength of concrete (the long term deflection reduced about 50% for compressive strength increased from 20 to 100 MPa). Additionally, the reinforcement at compressive zone is less benefit in decrease the long-term deflection when use the high strength concrete.

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The creep behavior for unidirectional and bidirectional fiber composite material has been studied experimentally under the effect of different water acidity level (pH=5,7&10) and moisture percentage (m= 1.24, 2.02 & 2.65%). It has been observed that the creep strain increase when the moisture percentage increased and decreased with increasing the acidity level. Different values of the applied stresses are tested which gave an increasing in the creep strain values with increasing the stress. The experimental creep data can be fitted with the general exponent creep equation. This equation is modified where the effect of moisture percentage and the applied stress on the creep strain are suggested as variables in the creep strain equation. The suggested equation gives a good criteria to be used to describe long time of creep strain in this work.

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The study aims to present new form to calculate the long-term deflections (time dependent) for reinforced concrete beams (normal & high strength).The presented form taking into account the effect of several factors such compressive strength of concrete, the reinforcement at compressive zone, cross section dimensions, and span length. The results of the presented form were compared with experimental results of other researchers, and a good agreement was obtained. Among the conclusions drawn, the long-term deflections are highly reduced by increasing the compressive strength of concrete (the long term deflection reduced about 50% for compressive strength increased from 20 to 100 MPa). Additionally, the reinforcement at compressive zone is less benefit in decrease the long-term deflection when use the high strength concrete.

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Rutting is recognized to be the major distress mechanism in flexible pavements as a result of increase in tire pressures and axle loads. Rutting is caused by the accumulation of permanent deformation in all or some of the layers in the pavement structure. The accumulation of permanent deformation in the asphalt surfacing layer is now recognized to be the major component of rutting in flexible pavements. This is a consequence of increased tire pressures and axle loads, which subjects the asphalt surfacing layer nearest to the tire-pavement contact area to increased stresses. This research evaluates information on the permanent deformation characteristics of asphalt-aggregate mixtures, with an emphasis on laboratory test techniques for measuring mixture resistance to permanent deformation. A comprehensive laboratory study was carried out using aggregate gradation for asphaltic surfacing course according with specification limit of SORB/R9, four percentage of asphalt cement were trialed in order to determine the optimum asphalt content for asphalt mixes, four levels of temperatures to accommodate the influence of temperature conditions and three levels of stresses. Uniaxial creep loading strain chosen as performance test to measure the permanent deformation of asphalt mixes. The results show that the temperature has a significant effect on permanent strain and, therefore, temperatures employed for design are relatively high to reproduce the most unfavorable pavement conditions.

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