This study investigated the shear performance of concrete beams with GFRP stirrups vs. traditional steel stirrups. Longitudinal glass fiber‐reinforced polymer (GFRP) bars were used to doubly reinforce the tested beams at both the top and bottom of their cross sections. To accomplish this, several stirrup spacings were provided. Eight beam specimens, measuring 300 × 250 × 2400 mm, were used in an experimental program to test under a two‐point concentrated load with an equal span‐to‐depth ratio until failure. Four beams in Group I have standard mild steel stirrups of 8 mm diameter, while four beams in Group II have GFRP stirrups with the same adopted diameter. The difference between the beams in each group was mainly due to the spacing between the reinforcing stirrups in the constant shear and pure bending spans. The test matrix consists of two beams with shear reinforcement equally distributed at 100 mm and 200 mm in constant shear and pure bending spans, respectively. Stirrups were placed uniformly over the whole effective span of the other six beams. In two beams, stirrups were placed 100 mm apart; in the other two, 75 mm; and in the last two, 50 mm. Test outcomes showed that GFRP stirrups, as opposed to steel stirrups, decreased the ultimate load by around 8%–27% based on stirrup spacing, while reducing the stirrup spacing increased the shear capacity. Also, the presence of compression GFRP bars and GFRP stirrups in the pure bending span led to an increase in the flexural stiffness of the tested beams. Consequently, this increase contributed to a higher ductility index. Accordingly, it is essential to prioritize adequate shear strength above flexural strength when designing GFRP‐reinforced concrete beams, as evidenced by the continuous observation of flexure‐shear cracking as the primary mode of failure in almost all tested beams.
This book presents the problem of tooth decay due to bacteria Streptococcus mutans one of methods of treatment using 3 extracts of S. persica (miswak) (aqueous, acetone and methanol) and prove its effectiveness and its impact on the gtf (B, C, and D) genes that code the glucosyltransferase (Gtf) enzymes that cause decay membrane compared to the usual means used for the prevention of tooth decay
The adsorption isotherms and kinetic uptakes of CO2 were measured. Adsorption isotherms were measured at two temperatures 309 K and 333 K and over a pressure range of 1 to 7 bar. Experimental data of CO2 adsorption isotherms were modeled using Langmuir, Freundlich and Temkin. Based on coefficient of correlation it was found that Langmuir isotherm model was well suited with the experimental data of CO2 adsorption isotherms. In addition, Adsorption kinetic of CO2 mixture with N2 containing 10 % by volume CO2 and 90 % by volume N2 were determined in a temperature 36 °C and under the atmospheric pressure .When the flow rate was increased from
... Show MoreParties as active units in this process in order to work must have access to sources of funding in order to maintain their political presence in society and participate in the process of electoral competition, To win the election, bolstering the huge role that money has played in influencing the principle of equality among contestants in the elections. Those who own money will have a greater chance of winning the elections while less competitive opportunities for others who do not own the money or what they own does not give them the competitive ability to win elections. From this point of view, controlling political finance through legal regulation and institutional, media and popular monitoring has become an important requirement
... Show MoreIn this research, the effect of multi-walled carbon nanotubes (MWCNTs) on the alumina/chromia (Al2O3/Cr2O3) nanocomposites has been investigated. Al2O3/Cr2O3-MWCNTs nanocomposites with variable contents of Cr2O3 and MWCNTs were fabricated using coprecipitation process and followed by spark plasma sintering. XRD analysis revealed a good crystallinity of sintered nanocomposites samples and there was only one phase presence of Al2O3-Cr2O3 solid solution. Density, Vickers microhardness, fracture toughness and fracture strength have been measured in the sintered samples. The results show tha
... Show MoreOne of the most severe problems with flexible asphalt pavements is permanent deformation in the form of rutting. Accordingly, the practice of adding fiber elements to asphalt mix to improve performance under dynamic loading has grown significantly in order to prevent rutting distress and ensure a safe and long-lasting road surface. This paper explores the effects of a combination of ceramic fiber (CF), a low-cost, easily available mineral fiber, and thermal insulator fiber reinforced to enhance the Marshall properties and increase the rutting resistance of asphalt mixes at high temperatures. Asphalt mixtures with 0%, 0.75%, 1.5%, and 2.25% CF content were prepared, and Marshall stability and wheel tracking tests were employed to stu
... Show MoreThe interlaminar fracture toughness of polymer blends reinforced by glass fiber has
been investigated. Epoxy (EP), unsaturated polyester(UPE), polystyrene (PS),
polyurethane (PU) and their blends with different ratios (10%PS/90%EP),
(20%PS/80%EP), (20%PU/80%EP) and (20%PU/80%UPE) were chosen as a matrices A
sheet of composites were prepared using hand lay -up method, these sheet were cut as the
double cantilever beam (DCB) specimen to determine interlaminar fracture toughness of
these composites .Its found that, blending of EP,UPE with 20% of PU will improve the
interlaminar fracture toughness ,but the adding of 10% PS, 20%PS to EP will decrease
the interlaminar toughness of these composites.
In this study, nanocomposites have been prepared by adding
multiwall carbon nanotubes (MWCNTs) with weight ratios (0, 2, 3,
4, 5) wt% to epoxy resin. The samples were prepared by hand lay-up
method. Influence of an applied load before and after immersion in
sodium hydroxide (NaOH) of normality (0.3N) for (15 days) at
laboratory temperature on wear rate of Ep/MWCNTs
nanocomposites was studied. The results showed that wear rate
increases with increasing the applied load for the as prepared and
immersed samples and after immersion. It was also found that epoxy
resin reinforced with MWCNTs has wear rate less than neat epoxy.
The sample (Ep + 5wt% of MWCNTs) has lower wear rate. The
immersion effect in base so
In this study, the mechanical properties of an epoxy and unidirectional woven carbon with fiberglass composite were experimentally investigated. When preparing the composite samples, American Society for Testing and Materials (ASTM)standard was used. Tensile, impact and flexural test were conducted to investigate the mechanical properties of the new produced epoxy Unidirectional Woven Carbon and Epoxy Fiberglass composites. The outcome showed that the strength of the produced samples increased with the increase in the number of unidirectional woven carbon layers added. Two methods were utilized: (1) woven carbon composite with glass fiber (2) woven carbon composite). The two methods of composite were compared with each other. The resul
... Show MoreCarbon-fiber-reinforced polymer (CFRP) is widely acknowledged as a leading advanced material structure, offering superior properties compared to traditional materials, and has found diverse applications in several industrial sectors, such as that of automobiles, aircrafts, and power plants. However, the production of CFRP composites is prone to fabrication problems, leading to structural defects arising from cycling and aging processes. Identifying these defects at an early stage is crucial to prevent service issues that could result in catastrophic failures. Hence, routine inspection and maintenance are crucial to prevent system collapse. To achieve this objective, conventional nondestructive testing (NDT) methods are utilized to i
... Show MoreThe study objectives were to 1) explore the real-world experience of hospital pharmacists with the differences in effectiveness safety, and interchangeability between biosimilar medicines and their reference biological counterparts, 2) reveal pharmacist recommendations to enhance the safety of biopharmaceutical medicines in public hospitals.
The study has a mixed-method design where the core component was qualitative (interviews) and the supplemental component was quantitative (adverse drug reaction, ADR, reports). This qualitative component included semi-structured (mostly face-to-face) interviews involving hospital pharmacists from different hospitals with experience with biological or biosimilar medicines. The interviews were c
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