Concrete filled steel tube (CFST) columns are being popular in civil engineering due to their superior structural characteristics. This paper investigates enhancement in axial behavior of CFST columns by adding steel fibers to plain concrete that infill steel tubes. Four specimens were prepared: two square columns (100*100 mm) and two circular columns (100 mm in diameter). All columns were 60 cm in length. Plain concrete mix and concrete reinforced with steel fibers were used to infill steel tube columns. Ultimate axial load capacity, ductility and failure mode are discussed in this study. The results showed that the ultimate axial load capacity of CFST columns reinforced with steel fibers increased by 28% and 20 % for circular and square columns, respectively. Also, the circular CFST columns exhibited better ductility than the square CFST columns due to better concrete confinement. Circular and square CFST columns with steel fibers showed improved ductility by 16.3% and 12%, respectively. The failure mode of the square CFST columns were local buckling which occurred near the end of columns, while, for the circular CFST columns, local buckling occurred near the mid-height. Also, the study involved sectional analysis that captured the behavior of CFST columns very well. The sectional analysis showed that increasing steel fiber content to 2% increased the axial load capacity by 51 and 38% for circular and square CFST columns, respectively. Furthermore, sectional analysis showed that doubling section size increased axial load capacity by approximately 4 and 5 times for circular and square columns, respectively.
In this study, NaOH dissolution method was applied to dissolve cellulose fibers which extracted from date palm fronds (type Al-Zahdi) taken from Iraqi gardens. In this process, (NaOH)-solution is brought into contact with the cellulose fibers at low temperature. Experiments were conducted with different concentrations of NaOH (4%, 6%, 8% and12%) weight percent at two cooling bath temperatures (-15 oC) and (-20oC). Maximum cellulose dissolution was 23 wt% which obtained at 8 wt% concentration of NaOH and at cooling bath temperature of -20oC. In order to enhance the cellulose fibers dissolution, the sample was pretreated with Fenton's reagent which consists of
... Show MoreIn this study, NaOH dissolution method was applied to dissolve cellulose fibers which extracted from date palm fronds (type Al-Zahdi) taken from Iraqi gardens. In this process, (NaOH)-solution is brought into contact with the cellulose fibers at low temperature. Experiments were conducted with different concentrations of NaOH (4%, 6%, 8% and12%) weight percent at two cooling bath temperatures (-15 oC) and (-20oC). Maximum cellulose dissolution was 23 wt% which obtained at 8 wt% concentration of NaOH and at cooling bath temperature of -20oC. In order to enhance the cellulose fibers dissolution, the sample was pretreated with Fenton's reagent which consists of hydrogen peroxide (H2O2), oxalic acid (C2H2O4) and ferrous sulfate (FeSO4). This
... Show MoreIn this study, NaOH dissolution method was applied to dissolve cellulose fibers which extracted from date palm fronds (type Al-Zahdi) taken from Iraqi gardens. In this process, (NaOH)-solution is brought into contact with the cellulose fibers at low temperature. Experiments were conducted with different concentrations of NaOH (4%, 6%, 8% and12%) weight percent at two cooling bath temperatures (-15 oC) and (-20oC). Maximum cellulose dissolution was 23 wt% which obtained at 8 wt% concentration of NaOH and at cooling bath temperature of -20oC. In order to enhance the cellulose fibers dissolution, the sample was pretreated with Fenton's reagent which consists of
... Show MoreDue to the potential cost saving and minimal temperature stratification, the energy storage based on phase-change materials (PCMs) can be a reliable approach for decoupling energy demand from immediate supply availability. However, due to their high heat resistance, these materials necessitate the introduction of enhancing additives, such as expanded surfaces and fins, to enable their deployment in more widespread thermal and energy storage applications. This study reports on how circular fins with staggered distribution and variable orientations can be employed for addressing the low thermal response rates in a PCM (Paraffin RT-35) triple-tube heat exchanger consisting of two heat-transfer fluids flow in opposites directions throug
... Show MoreThis work introduces a newly synthesized triazole derivative, 5-([(2-furanyl)methyl]-thiomethyl)-4-(naphtha-2-yl)-3-hydroxyl-4H-1,2,4-triazole (FTNT), as an effective corrosion inhibitor for carbon steel A106 G/B in 0.1 M HCl solution. The structure of the novel derivative was confirmed by FTIR, 1 H NMR, and 13 C NMR spectra. Potentiodynamic polarization measurements reveal that FTNT markedly suppresses corrosion, with inhibition efficiency reaching 81.6% at 600 ppm. Thermodynamic analysis indicates spontaneous, physisorption/chemisorption-augmented adsorption of FTNT on the steel surface, best described by the Freundlich isotherm. Atomic force microscopy (AFM) surface examination demonstrated that a protective FTNT coating precipitated on
... Show MoreIn this study, a mercapto-quinazolinone derivative, 3-(4-Bromobenzyl)-2-mercaptoquinazolin-4(3H)-one (compound B), was synthesized and assessed as a corrosion inhibitor for carbon steel (CS45) in 1M hydrochloric acid. The synthesis began with anthranilic acid and involved two main steps: first, the formation of a thiocyanate intermediate, followed by its reaction with anthranilic acid to produce compound B. The chemical structure of the synthesized compound was confirmed using FT-IR, 1H-NMR, and 13C-NMR techniques. The corrosion inhibition performance of compound B was evaluated at different concentrations (0.01, 0.05, 0.1, and 0.3 M) and temperatures (293, 303, and 313 K) in acidic media. Potentiodynamic polarization measu
... Show MoreIn this study, poly4-(nicotinamido)-4-oxo-2-butenoic acid (PNOE) was prepared by the electro polymerization of 4-(nicotinamido)-4-oxo-2-butenoic acid (NOE) monomer on a 316 stainless steel (St.St) which acts as an anticorrosion coating. Fourier transforms infrared (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), and cyclic voltammetry were used to diagnose the structure and the properties of the prepared polymer layer. The corrosion behavior of the uncoated and coated 316 St.St were evaluated by using an electro chemical polarization technique in 0.2 M hydrochloric acid solution as a corrosive medium at a temperature range of 293 to 323 K. Nano materials, such as nano ZnO and graphene were added in di
... Show MoreIn 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