For more than a decade, externally bonded carbon fiber reinforced polymer (CFRP) composites successfully utilized in retrofitting reinforced concrete structural elements. The function of CFRP reinforcement in increasing the ductility of reinforced concrete (RC) beam is essential in such members. Flexural and shear behaviors, ductility, and confinement were the main studied properties that used the CFRP as a strengthening material. However, limited attention has been paid to investigate the energy absorption of torsion strengthening of concrete members, especially two-span concrete beams. Hence, the target of this work is to investigate the effectiveness of CFRP-strengthening technique with regard to energy absorption of two-span RC beams subjected to pure torsion. The experimental program comprises the investigation of two groups; the first group comprises eight un-strengthened beam specimens, while the second group consists of eight strengthened beam specimens tested under torsional forces. The energy absorption capacity measured from the area under the curve of torque-angle of twist for tested beams. Two parameters were studied, the influence of concrete compressive strength and the angle of a twist. Experimental results indicated that all beams wrapped with CFRP sheet display superior torsional energy absorption capacity compared to the control specimens. The energy absorption may consider as a safety index for the torsional capacity of two-span RC beams under service loadings. Therefore, it is possible to avoid structural as well as material damages by understanding the concept of energy absorption that is one of the important experimental findings presented in this study.
The dynamic behavior of laced reinforced concrete (LRC) T‐beams could give high‐energy absorption capabilities without significantly affecting the cost, which was offered through a combination of high strength and ductile response. In this paper, LRC T‐beams, composed of inclined continuous reinforcement on each side of the beam, were investigated to maintain high deformations as predicted in blast resistance. The beams were tested under four‐point loading to create pure bending zones and obtain the ultimate flexural capacities. Transverse reinforcement using lacing reinforcement and conventional vertical stirrups were compared in terms of deformation, strain, and toughness changes of the tes
To promote sustainable steel-concrete composite structures, it is essential to develop special shear connectors that facilitate accelerated construction and deconstruction. A lockbolt demountable shear connector (LBDSC) was recently proposed. While the LBDSC has been evaluated using horizontal and vertical (standard) push-out tests, it is essential to further assess the disassembly mechanism and the positive flexural performance of prefabricated demountable composite beams (PDCBs) under both serviceability and ultimate limit states. Two full-scale test specimens of PDCBs with LBDSC were designed with partial shear connections and assessed using a three or four-point load beam setup under both cyclic and static monotonic loading conditions.
... Show MoreThis study aimed to evaluate the surface changes of commercial pure Titanium disks (CP Ti) and the Ti 13Nb 13 Zr (Alloy) with a zigzag pattern of laser surface treatment. In vitro, experimental study of CNC Laser treatment on the CP Ti and Alloy disks. Texturing the surfaces of CP Ti and Alloy disks via CNC laser, the sample disks were analyzed using surface roughness, wettability and FESEM. The FESEM revealed a proper increase in the surface texturing and roughness on macro and micro measures without crack formation or dramatic change of the core substance of the CP Ti and Alloy disks. The CNC laser is an effective and suitable method for surface texturing CP Ti and Alloy for dental implantology. Keywords: Commercial pure Titanium;
... Show MoreThis study explored the development and qualities of the response of electrochemical properties of enrofloxacin-selective electrodes using precipitation based on producing phosphotungstic, after utilizing a matrix of polyvinyl chloride (PVC) and dibutyl phthalate or dibutyl phosphate as a plasticizer. The resulting membrane sensors were an enrofloxacin-phosphotungstic electrode (sensors 1) and an ENR-DOP-PTA electrode (sensors 2). Linear responses of (ENR-DBPH-PTA) and (ENR-DOP-PTA) within the concentration ranges of 2.1×10-6-10-1 and 3.0×10-6-10-2 mol. L-1, respectively, for both sensors were observed. Slopes of 51.61±0.24 and 39.40± 0.16 mV/decade and pH ranges equal to 2.5-8.5
... Show MoreTwo simple, rapid, and useful spectrophotometric methods were suggest or the determination of sulphadimidine sodium (SDMS) with and without using cloud point extraction technique in pure form and pharmaceutical preparation. The first method was based on diazotization of the Sulphdimidine Sodium drug by sodium nitrite at 5 ºC, followed by coupling with α –Naphthol in basic medium to form an orange colored product . The product was stabilized and its absorption was measured at 473 nm. Beer’s law was obeyed in the concentration range of (1-12) μg∙ml-1. Sandell’s sensitivity was 0.03012 μg∙cm-1, the detection limit was 0.0277 μg∙ml-1, and the limit of Quantitation was 0.03605μg
... Show MoreThe study aimed to recommend a new spectrophotometric-kinetic method for determination of carbamazepine (CABZ) in its pure form and pharmaceutical forms. The proposed procedure based on the coupling of CABZ with diazotized sulfanilic acid in basic medium to yield a colored azo dye. Factors affecting the reaction yield were studied and the conditions were optimized. The colored product was followed spectrophotometrically via monitoring its absorbance at 396 nm. Under the optimized conditions, two method (the initial rate and fixed time (10 minute)) were applied for constructing the calibration graphs. The graphs were linear in concentration ranges 2.0 to 18.0 µg.mL-1 for both methods. The proposed was applied successfully in
... Show MoreSimple, precise and economic batch and flow injection analysis (FIA)-spectrophotometric methods have been established for simultaneous determination of salbutamol sulfate (SLB) in bulk powder and pharmaceutical forms. Both methods based on diazotization coupling reaction of SLB with another drug compound (sulfadimidine) as a safe and green diazotization agent in alkaline medium. At 444 nm, the maximum absorption of the orange azo-dye product was observed. A thorough investigation of all chemical and physical factors was conducted for batch and FIA procedures to achieve high sensitivity. Under the optimized experimental variables, SLB obeys Beer’s law in the concentration range of 0.25-4 and 10-100 μg/mL with limits of detection of 0.0
... Show MoreSimple, precise and economic batch and flow injection analysis (FIA)-spectrophotometric methods have been established for simultaneous determination of salbutamol sulfate (SLB) in bulk powder and pharmaceutical forms. Both methods based on diazotization coupling reaction of SLB with another drug compound (sulfadimidine) as a safe and green diazotization agent in alkaline medium. At 444 nm, the maximum absorption of the orange azo-dye product was observed. A thorough investigation of all chemical and physical factors was conducted for batch and FIA procedures to achieve high sensitivity. Under the optimized experimental variables, SLB obeys Beer’s law in the concentration range of 0.25-4 and 10-100 μg/mL with limits of detection o
... Show MoreCitrus fruit contain variety of flavonoids such as Hesperidin (the principal flavonoid in oranges and grapefruit). Hesperidin is found in high concentration in fruit peel of oranges and in substantially lower concentration in juice of these fruits. Hesperidin was extracted from oranges peel by treating the peels with calcium hydroxide. HPLC technique was used to determine hesperidin. Hesperidin was saperated and purified in a purity of about 90.1-95.7% and yield about 1.5 %w/w from oranges peel dry powder. Both hesperidin and oranges peel extract showed significan antibacterial activity. Sensitivity to hesperidin and oranges peel extracts were not similar for the chosen bacteriaCrude orange peel extract gave a various antimicro
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