This paper reports a comprehensive study on the behavior of concavely curved soffit reinforced concrete (RC) beams strengthened in flexure with carbon fiber-reinforced polymer (CFRP) composites under static loading. The main objective of this paper is to explore the effect of surface concavity on the bond performance of externally bonded wet layup CFRP sheets and laminates. An experimental program consisting of flexural strengthening of 24 RC beams with concavely curved soffits was carried out. All specimens were simply supported RC beams tested under three-point bending. Of the 24 beams, 6 beams were flat soffit RC beams, and the remainder were fabricated with concavely curved soffits with a degree of curvature that is ranging from 5 mm/m to 20 mm/m. All tested specimens were 2,700-mm long and had a constant cross section at midspan of 140-mm wide × 260-mm deep. The experiments showed that all strengthened beams failed by intermediate crack-induced (IC) debonding of the CFRP. The experimental results were then used, together with those for other specimens in the literature to set recommendations for strengthening concavely curved RC beams.
In this paper, the probabilistic behavior of plain concrete beams subjected to flexure is studied using a continuous mesoscale model. The model is two-dimensional where aggregate and mortar are treated as separate constituents having their own characteristic properties. The aggregate is represented as ellipses and generated under prescribed grading curves. Ellipses are randomly placed so it requires probabilistic analysis for model using the Monte Carlo simulation with 20 realizations to represent geometry uncertainty. The nonlinear behavior is simulated with an isotropic damage model for the mortar, while the aggregate is assumed to be elastic. The isotropic damage model softening be
This study is a numerical investigation of the performance of reinforced concrete (RC) columns after fire exposure. This study aims to investigate the effect of introducing lateral ties and using the RC jacket on improving post-fire behavior of these columns, the effect of the duration of the fire on ultimate load of columns. The analysis was performed through ABAQUS, a 3D – non-linear finite element program. 4 m tall lengthening square RC column with a cross- section of 0.4 m × 0.4 m was used as a test specimen. The RC column was reinforced by 4Ø28 mm longitudinal bars bonded by steel tie bars of Ø10 mm spaced at 400 mm. The firing temperature was increased to 60
Background: The surface properties of the titanium alloy plays a significant role in the bond of the dental implant with living bone and modification of the implant surface could enhance osseointegration. This study was aimed to investigate the effect of different durations of heat treatment on the surface properties of titanium alloy for dental implants. Materials and methods: Twenty disks of (Ti-6Al-4V) alloy were prepared. The sample was divided into four test groups to study the effect of different duration of heat treatment to the surface topography; surface chemistry, titanium oxide layer thickness, blood contact angle, & blood drop diameter of titanium alloy samples were investigated to evaluate the effect of different durations of
... Show MoreBackground: with the advent of new postmaterial in dentistry, it has become important to measure fitness of post restoration along the horizontal plane of the root space.This study aimed to measure and compare, the cement film thickness of conventional zinc phosphate cement in micrometer between the post and root dentin along horizontal plane at different post space regions (coronal, middle and apical) of four types of posts, by using stereomicroscopy. Material and methods: Thirty-two extracted human maxillary canines, mandibular canines and maxillary central incisors (n=32) were instrumented with ProTaper system files (hand use) and obturated with gutta-percha for ProTaper and AH26® root canal sealer. After 24hrs of incubation at 37ºC, p
... Show MoreBackground: Complete analysis of facial profile should also include an evaluation of soft tissue morphology. Materials and Method:The sample consisted of 90 Iraqi adults (45 males and 45 females) aged 18-25 years from Baghdad city divided into 3 groups according to the ANB angle with 30 subjects in each group (15 males and 15 females) for class I, II and III. Lateral cephalometric radiograph was taken for each subject and 8 angular and 5 linear measurements were identified and determined, t-test, ANOVA and LSD test were used to compare between both genders and between different classes. Results:Showed that females had greater angular measurements and smaller linear measurements with more lip prominence than males in all classes, there was m
... Show MoreAbstract: When it comes to applications in welding, cutting, and surface engineering, the utilization of high-power fiber-delivered beams from solid-state lasers offers several benefits. This paper addresses the issue of cleaning the surface of the samples with different spot sizes (50, 100 and 200) (industrial ytterbium fiber laser) to prepared it to be welded. Angular laser cleaning with incident angles (5, 10, 15, 20, 25, 30) ° with different powers (3, 5, 7, 10) W and hatch distance 0.001 was use for implemented.
A new hetrocyclic liquid crystal compounds containing 1,3,4-oxadiazole with different substituted in para position (Bromo, Chloro, Nitro and Methyl) were synthesized and characterized by melting points, FTIR Spectroscopy and 1HNMR spectroscopy for [Cl-SR6] and [NO2-SR6] compounds. The liquid crystalline properties of the synthesized compounds were studied by using hot-stage polarizing optical microscopy (POM), so they determined the transition enthalpies and entropies by using differential scanning calorimetery (DSC). All of the compounds show mesomorphic properties. The compounds [Br-SR6], [Cl-SR6] and [NO2SR6] exhibit an enantiotropic dimorphism smectic (Sm) phase, while the compounds [MeSR6] showed nematic (N) phase throw cooli
... Show MoreA new hetrocyclic liquid crystal compounds containing 1,3,4-oxadiazole with different substituted in para position (Bromo, Chloro, Nitro and Methyl) were synthesized and characterized by melting points, FTIR Spectroscopy and 1HNMR spectroscopy for [Cl-SR6] and [NO2-SR6] compounds. The liquid crystalline properties of the synthesized compounds were studied by using hot-stage polarizing optical microscopy (POM), so they determined the transition enthalpies and entropies by using differential scanning calorimetery (DSC). All of the compounds show mesomorphic properties. The compounds [Br-SR6], [Cl-SR6] and [NO2SR6] exhibit an enantiotropic dimorphism smectic (Sm) phase, while the compounds [MeSR6] showed nematic (N) phase thro
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