Stress-strain behaviour of unconfined and confined hybrid glass/steel fibre self-compacting concrete

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Introduction
Using the stress-strain test results, a mathematical model was developed to predict the stressstrain behavior of SCC and FRSCC in constrained and unconstrained conditions [1][2]. The proposed model is based on the mathematical equations of Saenz and Mansur. The Mansur model applies to finite and unconstrained fibrous and non-fibrous concrete [3]. We find that the model based on the Mansur equation is in good agreement with the experimental values as it includes fiber confinement parameters and lateral confinement effects [4]. The ductility modulus is the ratio of the strain at 85% of the ultimate stress on the descending portion of the curve to the strain on the ascending portion of the curve [5][6][7]. A quantitative measure of the increase in ductility when introducing different types of fibers is the ratio of the axial strain at 85% of the maximum axial stress to the axial strain at the maximum stress in the descending portion of the stress-strain curve. h is Є0.85 Dsc/Є0, called the plasticity ratio, given by Martinez (1984) [8][9][10][11].

Mix design
The following data is considered for the study: 1. Mix design based on Nan Su mix design criteria 2. Packing factors considered are from 1.12 to 1.18 3. Fine aggregates to total aggregates (s/a) ratio between 0.50 and 0.57 4. Types of SCC mixes considered are Plain SCC (PSCC) and Hybrid glass/steel fibred SCC (HFRSCC) 5. For confinement of concrete cylinders, 0, 3, 4, 5 and 6 hoops are used 3 Optimization of packing factor and s/a ratio PSCC1 indicates the plain SCC mix made with packing factor 1.12 and s/a ratio 0.50 whereas PSCC2 indicates the plain SCC mix made with packing factor 1.14 and s/a ratio 0.57. The above two PSCC mixes yield maximum compressive strengths and are optimally chosen from various PSCC mixes made with various packing factors from 1.12 to 1.18 and s/a ratio from 0.50 to 0.57.

Dosage of steel and glass fibre
For the PSCC1 or PSCC2 mixes, add various percentage of glass fibre by volume of concrete and determine the compressive strengths. The optimum dosage of steel fibre is the one which yields maximum compressive strength. Same procedure is adopted to determine the optimum dosage of glass fibre.

Discussions
As can be seen, the maximum working load limit and elongation at peak load are higher for HFRSCC than for PSCC. These figures clearly show that the use of steel and fiberglass improves strength-holding capacity and allows for higher load absorption at peak loads. This is likely due to the presence of small, discrete, high-dispersion glass fibers that inhibit cracking at the micro level and steel fibers that inhibit late failure. However, if the containment is in the form of lateral ring boundaries, the effect of the fibers is of little importance. This clearly shows that HFRSCC has a stronger containment effect compared to his PSCC. In both cases, fiber hybridization in SCC showed improvement in confined conditions using steel hoops. The intensity inclusion parameter was found to range from 0.055 to 0.094 for various inclusion percentages. Strength increase rate, ie. H. The intensity ratio between trapped SCC ("fo") and untrapped SCC ("fo") is between 1.164 and 1.631. Moreover, the strength confinement factor of HFRSCC is lower, suggesting that HFRSCC has improved confinement compared to PSCC.

Conclusions
Transverse reinforcement to understand the effectiveness of shear bars on M 40 grade simple self-compacting concrete (PSCC) and hybrid glass/steel fiber reinforced self-compacting concrete (HFRSCC) mixtures under monotonically increasing axial compression. Study the cylinder bounded by . The following conclusions can be drawn from the stress-strain diagram: 1) The mathematical formulas proposed by Saenz and Mansur were validated to predict the stress-strain behavior of SCC and HFRSCC in constrained and unconstrained states.

2)
To develop SCC, Nan-Su mixed construction method is applied based on filling rate 1.12 and 1.14 and S/A ratio 0.50 and 0.57.

3)
For hybrid fiber-reinforced SCC mixtures, the loadings of steel and glass fibers are 1% and 0.05% of the concrete volume, respectively.

4)
For M 40 grade simple self-compacting concrete (PSCC) and hybrid glass/steel fiber reinforced self-compacting concrete mix (HFRSCC) with different volume ratios, stresses, strains, elastic moduli, plasticity ratios and ductility ratios, unlimited The intensity ratio of is: evaluated experimentally. 5) Maximum load capacity and peak load are higher for HFRSCC than for PSCC. The presence of steel and glass fibers increases strength bearing capacity and allows it to withstand greater loads during peak loads.

5)
If the confinement is in the form of a lateral ring confinement, the fiber effect is almost negligible. This clearly shows that HFRSCC has a stronger containment effect compared to his PSCC. The strength confinement factor is lower for HFRSCC, suggesting that HFRSCC offers a superior confinement factor compared to PSCC.