The effect of considering the third dimension in mass concrete members on its cracking behavior is investigated in this study. The investigation includes thermal and structural analyses of mass concrete structures. From thermal analysis, the actual temperature distribution throughout the mass concrete body was obtained due to the generation of heat as a result of cement hydration in
addition to the ambient circumstances. This was performed via solving the differential equations of heat conduction and convection using the finite element method. The finite element method was also implemented in the structural analysis adopting the concept of initial strain problem. Drying shrinkage volume changes were calculated using the procedure suggested by ACI Committee 209 and inverted to equivalent temperature differences to be added algebraically to the temperature differences obtained from thermal analysis. Willam-Warnke model with five strength parameters is used in modeling of concrete material in which cracking and crushing behavior of concrete can be included. The ANSYS program was employed in a modified manner to perform the above analyses.
A thick concrete slab of 1.5m in thickness and 10m in length was analyzed for different widths 2, 4, 8, and 10m to produce different aspect ratios (B/L) of 0.2, 0.4, 0.8, and 1.0 respectively. The results of the analyses show an increase in cracking tendency of mass concrete member as the aspect ratio of the same member is increased due to the effect of transverse base restraint. Accordingly, such effect cannot be ignored in the analysis of base restrained mass concrete structures subjected to temperature and drying shrinkage volume changes.
Abstract Twelve isolates of bacteria were obtained from samples of different soils and water amended with 100µg/ml of five heavy metals chlorides (i.e: Aluminum Al+2, Iron Fe+2, Lead Pb+2, Mercury Hg+2 and Zinc Zn+2). Four isolates were identified as Bacillus subtilis and B. subtilis (B2) isolate was selected for this study according to their resistance to all five heavy metals chlorides. The ability of B. subtilis (B2) isolate for growing in different concentration of heavy metals chlorides ranging from 200-1200 µg/ml was tested. The highest conc. that B. subtilis (B2) isolate tolerate was 1000 µg/ml for Al+2, Fe+2, Pb+2, and Zn+2and 300 µg/ml for Hg+2 for 24hour. The effect of heavy metals chlorides on bacterial growth for 72 hrs was
... Show MoreThe aim of this study is to investigate the role of prodigiosin on P. aeruginosa' s biofilm genes involved in the pathogenicity and persistency of the bacteria; Materials and methods: Gram negative bacterial isolates were taken from burn and wounds specimen obtained from some of Baghdad hospitals. Forty six isolates were identified as Pseudomonas aeruginosa and four isolates as Serratia marcescens by using biochemical tests and VITEK 2 compact system. Susceptibility test was performed for all P. aeruginosa isolates, the results showed that 100% were resistant to Amikacin and 98% were sensitive to Meropenem. Resistant isolates were tested for biofilm formation; the strong and moderate isolates (17) were detected by PCR for AlgD gene
... Show MoreIn this study, Cobalt Oxide nanostructure was successfully prepared using the chemical spray pyrolysis technique. The cobalt oxide phase was analysed by X-ray Diffraction (XRD) and proved the preparation of two cobalt oxide phases which are Co3O4 and CoO phases. The surface morphology was characterized by Scanning Electron Microscope (SEM) images showing the topography of the sample with grain size smaller than 100 nm. The optical behavior of the prepared material was studied by UV-Vis spectrophotometer. The band gap varied as 1.9 eV and 2.6 eV for Co3O4 prepared from cobalt sulphate precursor, 2.03 eV and 4.04 eV for Co3O4 prepared from cobalt nitrate precursor, 2.04 eV and 4.01 eV for CoO prepared from cobalt chloride precursor where th
... Show MoreConcrete is widely used in construction materials since early 1800's. It has been known that concrete is weak in tension, so it requires some addition materials to have ductile behavior and enhance its tensile strength and strain capacity to improve their uses. In this study reactive powder concrete (RPC) was used with steel fiber by using different types of cement; (Ordinary Portland cement (OPC) and/or Portland- Limestone cement (PLC)) with three types of mixtures (OPC at the first mix, 50 % OPC and 50 % PLC at the second mix and PLC at the third mix). The behavior of RPC with steel fibers on compressive strength and tensile strength of concrete with different ages of curing (7, 14, 28 and 60) days and shrinkage have been studied. The clo
... Show MoreIn this work, synthesis of conducting polymeric films namely, PVC thin films was carried out containing Schiff base (L) with Cu2+, Cr3+, Ni2+, Co2+, in addition to inspecting the possibilities of measuring energy gap values of PVC-L-M with variety metal ions. These new polymeric films (PVC-L-M) were characterized by FTIR spectrophotometry, energy gap and surface morphology. The optical data recorded that the band gap values are influenced by the type of metals. All modified films have a red shift in optical properties in the ultraviolet region. The PVC-L-Co(II) was the lowest value of the optical band gap, 3.1 eV.
In this research the behavior of reinforced concrete columns with large side openings under impact loads was studied. The overall cross sectional dimensions of the column specimens used in this research were (500*1400) mm with total height of (14000) mm. The dimensions of side openings were (600*2000) mm. The column was reinforced with (20) mm diameter in longitudinal direction, while (12) mm ties were used in the transverse direction. The effect of eccentric impact loads on the horizontal and vertical displacement for this column was studied. &
... Show MoreThis study was conducted in the Faculty of Agricultural Engineering Sciences - University of Baghdad in the field of sheep and goats in the Department of Animal Production. Effect of different concentrations of bovine albumin on some semen characteristics of frozen rams. Used in this experiment, 3 rams and their ages ranging from 2.5-3 years. The sample of the semen was diluted with Tris dilution with the addition of 10 ml of egg yolk per 100 ml, the sample by 1:1 with the tris and then the collection of sperm samples (Pooling) after the semen was divided into four treatments Control and bovine albumin at concentrations of 5, 7.5 and 10% and then complete dilution 10: 1, at 5C, dilution 20: 1, containing 5% glycerol per 100 ml. The results
... Show MoreMethotrexate (MTX)is a multiple therapeutic drug, it's used in treatment of ectopic pregnancy, neoplastic disease, autoimmune disorders, and inflammatory conditions. It’s associated with a spectrum of side effect that includes damage to the (liver, kidney, lung and bone marrow). MTX has been associated with fetal malformations in( nervous, skeletal, gastrointestinal, and cardiac) system, and even fetal death. The study was conducted to test the effect of two doses of MTX (5and 10mg/kg) on the development of the mice liver during two gestational age (day11 and day 17) of pregnancy.18 healthy female mice were divided into three groups ,first group (control) was injected with normal saline ,second group injected with 5mg/kg and third grou
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