Stress-strain relationships

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Uniaxial Tensile Stress-Strain Relationships of RC Elements Strengthened with FRP Sheets

Uniaxial Tensile Stress-Strain Relationships of RC Elements Strengthened with FRP Sheets

The comparison between the stress strain relationships of steel in FRP RC element and those of bare rebars is shown in Fig. 7a-7c. The results show that the apparent yielding stress was altered due to the existence of the FRP. It can also be observed that the difference between the yield stress of bare rebar and apparent yield stress becomes smaller with the increase of FRP stiffness. This effect is more evident for #3 rebar compared with #4 and #5 rebar. This can be explained that in the specimen with a smaller internal steel reinforcement ratio, the FRP tends to work more effectively in crack width control. As a result, the local yielding of the rebar at the crack location was postponed, which leads to an increase of the apparent yield stress. Based on this phenomenon, the steel reinforcement ratio  s in Eqn. (19) was proposed to be replaced by a new ratio called equivalent reinforcement ratio  e , which considered the contribution of FRPs. The following equations were proposed to calculate  e :
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Mechanical Performance and Stress–Strain Relationships for Grouted Splices Under Tensile and Cyclic Loadings

Mechanical Performance and Stress–Strain Relationships for Grouted Splices Under Tensile and Cyclic Loadings

Mechanical behavior of the coupling sleeves was investi- gated in terms of strain development and peak strain distri- butions at ultimate loads on their external surfaces both in the longitudinal and transverse directions. As an example, Fig. 7 presents the peak strain distribution on the surface of specimen IT-H400D25. The values on the x axis denote the distances from the narrow end of the sleeve to the observed points. First, it was found that along the longitudinal direc- tion, all coupling sleeves were in tension. The peak strain of each specimen appeared in the midsection and decreased gradually towards the two sleeve ends. Second, in the transverse direction, the strains were relatively small com- pared to those in the longitudinal direction. Peak strains were Table 7 Test results for specimens under incremental and repeated tensile loadings.
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Stress : strain relationships for confined concrete : rectangular sections

Stress : strain relationships for confined concrete : rectangular sections

ultimate concrete strain = minimum and maximum average 1ongitudina 1 strains corresponding to the maximum stress in concrete 2} = steel yield strain = concrete strain at maximum stress l[r]

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Mathematical Model for Predicting Stress-Strain Behaviour of Bacterial Concrete

Mathematical Model for Predicting Stress-Strain Behaviour of Bacterial Concrete

For decades, many researchers developed empirical and semi-empirical stress-strain relationships to describe the behavior of concrete in compression. The better the stress-strain model, the more reliable is the estimate of strength and deformation behavior of concrete structural members. The compressive stress-strain behavior of concrete is a significant issue in the flexural analysis of reinforced concrete beams and columns. The stress-strain curve of concrete is also useful for investigating the ductility of concrete. Moreover, the total area under the stress-strain curve can represent the amount of energy absorbed by the specimen under loading. A stress - strain curve is a graph obtained by plotting the values of stresses and strains obtained by testing cylinders of standard size made with concrete under uni-axial compression. It is observed from the stress-strain plots that, no portion of the curves is in the form of a straight line even though the stress strain relation for cement paste and aggregate when tested individually is practically linear. In concrete the rate of increase of stress is less than that of increase in strain because of the formation of micro cracks, between the interfaces of the aggregate and the cement paste. Thus the stress strain curve is not linear. In controlled concrete, the value of stress is maximum corresponding to a strain of about 0.002 and further goes on decreasing with the increasing strain, giving a dropping curve till it terminates at ultimate crushing strain. After obtaining the stress-strain behavior of controlled and bacterial concrete mixes experimentally, an attempt is made by validating it against the analytical stress-strain curves for controlled and bacterial concrete mixes.
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Effects of Defects on the Mechanical Properties of Kinked Silicon Nanowires

Effects of Defects on the Mechanical Properties of Kinked Silicon Nanowires

Figure 8a shows the final tensioning profile of each NW. All the NWs fractured at the middle. It means that the internal defect has little effect on the fracture location. It can also be noted that the crack on the other kinks decreases as the size of the defect increases, while the fracture area seems to concentrate towards the middle of the NW. Figure 8b shows the stressstrain relationships of KSiNWs during tensioning. Before yield, the stressstrain relationship is almost the same. How- ever, large internal defects cause a large reduction of fracture strength.
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Nonlinear analysis of axially loaded circular concrete-filled stainless steel tubular short columns

Nonlinear analysis of axially loaded circular concrete-filled stainless steel tubular short columns

Experiments show that the ultimate compressive strength of stainless steel is much higher than its tensile strength. The full-range two-stage constitutive model for stainless steels assumes that stainless steels follow the same stressstrain behavior in compression and tension, which may underestimate the compressive strength of stainless steel tubes. This paper presents a fiber element model incorporating the recently developed full-range three-stage stressstrain relationships based on experimentally observed behavior for stainless steels for the nonlinear analysis of circular concrete-filled stainless steel tubular (CFSST) short columns under axial compression. The fiber element model accounts for the concrete confinement effects provided by the stainless steel tube. Comparisons of computer solutions with experimental results published in the literature are made to examine the accuracy of the fiber element model and material constitutive models for stainless steels. Parametric studies are conducted to study the effects of various parameters on the behavior of circular CFSST short columns. A design model based on Liang and Fragomeni’s design formula is proposed for                                                             
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Short-term Deflections of Reinforced Concrete Beams

Short-term Deflections of Reinforced Concrete Beams

This chapter presented an investigation into the early-age material properties of concrete that impact computed instantaneous deflections. The experimental stress-strain response and material properties reported by others (Khan 1995, Jin et al. 2005) included concrete from ages of 9.7 hours to 91 days. In the present study, concrete ages up to 28 days were investigated, very young concrete is deemed to be less than 24 hours old, and young concrete is considered to be from one to three days old. The accuracy of the Todeschini (1964) and Modified Hognestad (1951) stress-strain relationships to model the experimental stress-strain responses was investigated because the behaviour of concrete at very young ages may differ markedly from that of mature concrete (MacGregor & Bartlett 2000). The flexural behaviour of sections at young ages can be quantified given variations in the concrete stress-strain relationship, so moment-curvature analyses based on conventional simplifying approximations, the reported concrete stress-strain data, and the Todeschini and Modified Hognestad relationships were performed. Deflections depend on member stiffness and so on the flexural rigidity, E c I cr . Early-age flexural
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Comparison of Nano-Mechanical Behavior between

Comparison of Nano-Mechanical Behavior between

indentation strain rate at the maximum load point are used, the strain-rate sensitivity can be 131. determined from a group of CRL nanoindentation tests under different loading rates [[r]

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METHODS : The current study aimed to investigate associations of psychomotor retardation PMR and clinical as well as biomarker characteristics of schizophrenia We recruited 40 healthy

METHODS : The current study aimed to investigate associations of psychomotor retardation PMR and clinical as well as biomarker characteristics of schizophrenia We recruited 40 healthy

PMR was strongly associated with executive functions, deficits in episodic and semantic memory,.. PHEM and negative ( PHEMN ) symptoms.[r]

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Emerging role of the integrated stress response upon viral infection

Emerging role of the integrated stress response upon viral infection

with two small initiation factors (eIF1 and eIF1A) [4,5]. PIC is recruited to the 5’methylguanine cap of mRNA through the eIF4F complex, the latter contains eIF4G and eIF4E. PIC migrates to the AUG start codon and then binds the Met-tRNAi anti-codon and the AUG start codon which facilitates protein synthesis. AUG recognition causes arrest of the scanning PIC and triggers conversion of eIF2 GDP-bound state via gated phosphate (Pi) release and GTPase-activating (GAP)factor eIF5. eIF2-GDP complex dissociate from 40S ribosomal complex and transforms to GTP with the help of eIF2B complex and enters another recycling of initiation of mRNA translation [6,7]. In stress condition, phosphorylated eIF2 is fully capable of forming an initiation-competent eIF2-TC, but following its release, phosphorylated eIF2-GDP tightly binds to and sequesters the guanine nucleotide exchange factor eIF2B, abrogating its activity. Most mRNA translation is reduced when eIF2α is phosphorylated. However, translation from certain mRNAs with at least two upstream open reading frames (uORFs) of appropriate type and position can be upregulated. The best-characterized mammalian examples are ATF4, ATF5 and CHOP. Upregulation of ATF4, ATF5 and CHOP function activates chaperon proteins to promote cellular recovery or activate cell death pathways upon sustained stress.
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Melatonin attenuates RVLM neuro-inflammation and sympathetic activation in stress-induced hypertension rats.

Melatonin attenuates RVLM neuro-inflammation and sympathetic activation in stress-induced hypertension rats.

resulting in the mechanism of immune regulation. Studies have shown that the active substances produced by the vascular endothelial system in body fluids, such as endothelin, nitric oxide and angiotensin aldosterone system (RAAS), show significant circadian rhythm changes and are significantly correlated with the circadian rhythm of blood pressure. In patients with hypertension, the changes of these humoral factors may be the pathological basis of abnormal blood pressure rhythm. Previous studies have shown that melatonin can reduce blood pressure by affecting vascular endothelial system and RAAS system [24, 25], but the mechanism is not completely clear. In this study, the stress-induced hypertension rat model was adopted to observe the antihypertensive effect of melatonin, and the central antihypertensive mechanism and target of melatonin were explored based on the neuroinflammation triggered by M1 polarization of microglia cells, providing experimental basis for further clarifying the mechanism of melatonin's involvement in regulating blood pressure.
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Physiological, Proteomic, and Biochemical analysis Reveal Possible Cross-Tolerance in

Physiological, Proteomic, and Biochemical analysis Reveal Possible Cross-Tolerance in

iv) Effect of water stress showed a high abundance of proteins involved in metabolism in. 518[r]

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1 IRES trans-acting factors, key actors of the stress

1 IRES trans-acting factors, key actors of the stress

LEF1 Lymphoid enhancer binding factor 1 GRSF1 G-rich RNA sequence binding factor 1 AANAT arylalkylamine N-acyltransferase FMRP fragile X mental retardation protein RRBP1 ribosome binding protein 1 NSAP nephritis strain-associated protein ELAV embryonic lethal abnormal vision ELAV1 ELAV-like protein 1

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Dynamic Shear Behaviour of Unweldable Aluminum Scandium (Al Sc) Alloy

Dynamic Shear Behaviour of Unweldable Aluminum Scandium (Al Sc) Alloy

respectively, under the same strain rate. Substituting the shear stress-strain data plotted in Fig. 3(a) into eq. (6), the temperature sensitivity can be calculated for the current experimental strain rate and temperature conditions. Figure 5(b) plots the temperature sensitivity against the shear strain for specimens deformed at strain rates between 8 10 2 s 1 and 2:8 10 3 s 1 at temperatures within two different temperature ranges, i.e. 25 C 150 C and 25 C 300 C, respectively. As shown, the temperature sensitivity in both temperature ranges increases with increas- ing shear strain and strain rate. For a constant shear strain and strain rate, the value of the temperature sensitivity parameter is higher in the lower temperature range. Therefore, it is evident that the shear flow behaviour of unweldable Al-Sc alloy is particularly sensitive to temperature changes under low temperature loading conditions.
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The stress strain characteristics of uranium

The stress strain characteristics of uranium

In all of the preceding discussion the model was assumed to be brought to equal strains in tension and compressiono If, on the other hand, the model is brought to the same total load and[r]

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Analysis of Stress- Strain and Deflection of Flexible Pavements Using Finite Element Method Case Study on Bako-Nekemte Road

Analysis of Stress- Strain and Deflection of Flexible Pavements Using Finite Element Method Case Study on Bako-Nekemte Road

The sample inspections selected may be provided by an estimate of the analysis of stress- strain and deflection of flexible pavements. By using the sampling technique to collect data from site (distress area), depend on the mean severe area, laboratory result, standard of specification of AASHTO or ERA, and laboratory staffs who know property of materials of the road. These collected data are input data, the output will be analyzed using ever stress software. 2.9. Data Processing and Analysis

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Hot Deformation Behavior of Cu-Sn-La Polycrystalline Alloy Prepared by Upcasting

Hot Deformation Behavior of Cu-Sn-La Polycrystalline Alloy Prepared by Upcasting

Above all, during hot working, strain hardening and dynamic recovery occurred simultaneously at low temperature or high strain rate. With dislocation proliferation, accretion, recombination, and annihilation, the dislocation distribution was observed first to be uneven and then gradually evolved into an independent cellular structure in different dislocation tangled areas [21]. This led to formation of dislocation cells and reduction in dislocation density. Consequently, stressstrain curve increased slowly at 400 C (Figures 2(a) and 2(b)). At high deformation temperatures or low strain rates, the deformation process was accompanied by the formation and growth of recrystallized crystal nuclei, and softening rate of the alloy appeared greater than or equal to the deformation hardening rate [23]. Thus, the stressstrain curve tended to stabilize (Figures 2(a) and 2(b) at 700 C). At deformation hardening rate equivalent to dynamic recovery and dynamic recrystallization rate, the stressstrain curve was stable (Figures 2(a) and 2(b) at 600  C). The reason for the above mentioned different laws can be attributed to the competition between dynamic hardening and dynamic softening phenomena.
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Flying-fox Heat Event Response Guidelines SEQ

Flying-fox Heat Event Response Guidelines SEQ

The HSE Forecaster may provide a few days notice as to a potential heat stress event, so a large part of a successsful response is preparation. If a HSE is predicted and the decision is made to respond, then clear criteria based on the environmental conditions, roost characteristics and the progression of the bats' behavioural responses to the heat on the day, will determine the timing of intervention. It needs to be recognised that it is not likely possible to save every bat on the day and a triage plan should be followed to achieve the ultimate aim: to minimise flying-fox suffering and deaths.
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Micro hydro power plant Shanping (Site reconstruction)

Micro hydro power plant Shanping (Site reconstruction)

Because Shanping hydro powerhouse was in the vicinity of the creek, it was struck by flood and flushed away along with diversion weir with green bridge, water supply channel along the [r]

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Modeling and Simulation of Stress and Strain of Chassis Structure for Wheeled Robot

Modeling and Simulation of Stress and Strain of Chassis Structure for Wheeled Robot

Observing Figure 4, we can see that the maximum equivalent stress, the maximum equivalent strain and the maximum total deformation of the robot chassis are 24.032MPa, 0.00012016 and 0.13862mm respectively, which are all in the allowable range. The stress, strain and deformation on the bearing seat holes are very small and redundant, so the thickness of this part is reduced from 27mm to 18mm preliminarily. In order to analyze the stress change on the disc structure, several sections were selected at key locations. Its stress and deformation are shown in Figure 4.
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