The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Muhammad N S Hadi - One of the best experts on this subject based on the ideXlab platform.
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Effect of Helical Pitch and Tensile Reinforcement Ratio on the Concrete Cover Spalling Off Load and Ductility of HSC Beams
2012Co-Authors: Nuri Elbasha, Muhammad N S HadiAbstract:In recent years a marked increase in the use of High Strength Concrete (HSC) has been evident in Australian building construction despite the fact that the current Australian design standard, AS3600 provides no design rules. HSC has been used extensively in civil construction projects world wide because it reduces the cross section and the weight for long construction members. High strength concrete and high strength steel are used together to increase the load capacity and reduce the beams' cross section. Using these two materials to design over reinforced beams will lead to huge reduction of cost, which is a desirable issue. However, the problem is the lack of ductility, hence such use is not allowed by the current codes of practice. Avoiding brittle compression failure by using proper confinement, which restrains the lateral expansion, leads to enhancements in the strength and ductility of concrete. Base and Red (1965) showed through limited experimental testing that double helical confinement enhances the strength and ductility of a beam of high Tensile longitudinal steel percentage. There is limited data regarding the strength, concrete cover spalling off, confined concrete strain and ductility for over reinforced HSC helically confined beams. This research provides experimental data to examine the effect of helical pitch and Tensile Reinforcement ratio on the concrete cover spalling off and displacement ductility for over reinforced HSC helically confined beam. Based on this, more study and data on the behaviour of confined HSC beams are needed. This paper presents the experimental results of testing eight full-scale beams with 4000 mm length and a cross section of 200 mm in width and 300 mm in depth. The variables in this research are helix pitch and longitudinal Reinforcement ratio. The main objective of this paper is to provide experimental data and study the effect of helical pitch and Tensile Reinforcement ratio on the concrete cover spalling off and displacement ductility for over reinforced HSC helically confined beam.
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The effect of confinement shapes on over-reinforced HSC beams.
Journal of Civil and Environmental Engineering, 2008Co-Authors: R Jeffry, Muhammad N S HadiAbstract:High strength concrete (HSC) provides high strength but lower ductility than normal strength concrete. This low ductility limits the benefit of using HSC in building safe structures. On the other hand, when designing reinforced concrete beams, designers have to limit the amount of Tensile Reinforcement to prevent the brittle failure of concrete. Therefore the full potential of the use of steel Reinforcement can not be achieved. This paper presents the idea of confining concrete in the compression zone so that the HSC will be in a state of triaxial compression, which leads to improvements in strength and ductility. Five beams made of HSC were cast and tested. The cross section of the beams was 200×300 mm, with a length of 4 m and a clear span of 3.6 m subjected to four-point loading, with emphasis placed on the midspan deflection. The first beam served as a reference beam. The remaining beams had different Tensile Reinforcement and the confinement shapes were changed to gauge their effectiveness in improving the strength and ductility of the beams. The compressive strength of the concrete was 85 MPa and the Tensile strength of the steel was 500 MPa and for the stirrups and helixes was 250 MPa. Results of testing the five beams proved that placing helixes with different diameters as a variable parameter in the compression zone of reinforced concrete beams improve their strength and ductility.
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effects of Tensile Reinforcement ratio and compressive strength on the behaviour of over reinforced helically confined hsc beams
Construction and Building Materials, 2007Co-Authors: Muhammad N S Hadi, Nuri ElbashaAbstract:Abstract The technology of high strength concrete has improved over the last decade. High strength concrete (HSC) is more brittle than normal strength concrete. The brittleness increases with the use of over-reinforced section, which fails suddenly without warning. Use of over reinforced sections is restricted in codes of practice of concrete design. This paper presents an experimental study of the behaviour of five HSC beams confined with helical Reinforcement. Concrete compressive strength in the range 72–95 MPa and Tensile Reinforcement ratio in the range 5.24–7.86% were used. The main results indicate that as the concrete compressive strength increases the displacement ductility index decreases and the load at spalling-off the concrete cover increases. Also, the displacement ductility index increases as the longitudinal Reinforcement ratio increases and the load at spalling-off the concrete cover decreases.
Nuri Elbasha - One of the best experts on this subject based on the ideXlab platform.
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Effect of Helical Pitch and Tensile Reinforcement Ratio on the Concrete Cover Spalling Off Load and Ductility of HSC Beams
2012Co-Authors: Nuri Elbasha, Muhammad N S HadiAbstract:In recent years a marked increase in the use of High Strength Concrete (HSC) has been evident in Australian building construction despite the fact that the current Australian design standard, AS3600 provides no design rules. HSC has been used extensively in civil construction projects world wide because it reduces the cross section and the weight for long construction members. High strength concrete and high strength steel are used together to increase the load capacity and reduce the beams' cross section. Using these two materials to design over reinforced beams will lead to huge reduction of cost, which is a desirable issue. However, the problem is the lack of ductility, hence such use is not allowed by the current codes of practice. Avoiding brittle compression failure by using proper confinement, which restrains the lateral expansion, leads to enhancements in the strength and ductility of concrete. Base and Red (1965) showed through limited experimental testing that double helical confinement enhances the strength and ductility of a beam of high Tensile longitudinal steel percentage. There is limited data regarding the strength, concrete cover spalling off, confined concrete strain and ductility for over reinforced HSC helically confined beams. This research provides experimental data to examine the effect of helical pitch and Tensile Reinforcement ratio on the concrete cover spalling off and displacement ductility for over reinforced HSC helically confined beam. Based on this, more study and data on the behaviour of confined HSC beams are needed. This paper presents the experimental results of testing eight full-scale beams with 4000 mm length and a cross section of 200 mm in width and 300 mm in depth. The variables in this research are helix pitch and longitudinal Reinforcement ratio. The main objective of this paper is to provide experimental data and study the effect of helical pitch and Tensile Reinforcement ratio on the concrete cover spalling off and displacement ductility for over reinforced HSC helically confined beam.
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effects of Tensile Reinforcement ratio and compressive strength on the behaviour of over reinforced helically confined hsc beams
Construction and Building Materials, 2007Co-Authors: Muhammad N S Hadi, Nuri ElbashaAbstract:Abstract The technology of high strength concrete has improved over the last decade. High strength concrete (HSC) is more brittle than normal strength concrete. The brittleness increases with the use of over-reinforced section, which fails suddenly without warning. Use of over reinforced sections is restricted in codes of practice of concrete design. This paper presents an experimental study of the behaviour of five HSC beams confined with helical Reinforcement. Concrete compressive strength in the range 72–95 MPa and Tensile Reinforcement ratio in the range 5.24–7.86% were used. The main results indicate that as the concrete compressive strength increases the displacement ductility index decreases and the load at spalling-off the concrete cover increases. Also, the displacement ductility index increases as the longitudinal Reinforcement ratio increases and the load at spalling-off the concrete cover decreases.
Mohammad Mohammadhassani - One of the best experts on this subject based on the ideXlab platform.
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an experimental study on the failure modes of high strength concrete beams with particular references to variation of the Tensile Reinforcement ratio
Engineering Failure Analysis, 2014Co-Authors: Mohammad Mohammadhassani, Meldi Suhatril, Mahdi Shariati, Shatirah Akib, M Arabnejad M KhanoukiAbstract:Abstract For many years, high-strength concrete (HSC) has been used in high-rise buildings and bridges. The primary reasons for selecting HSC are to produce a more economical product, provide a feasible technical solution, or a combination of both. Despite a lot of advantages in the usage of HSC, it exhibits a brittle failure in comparison with normal strength concrete (NSC). For a comprehensive discussion on the failure of HSC beams, a total of six full scale reinforced HSC beams have been designed based on ACI code provisions and cast with compressive strength in the range of 65 MPa ⩽ f c ′ ⩽ 75 MPa and tested under two-point top loading. The general behaviour of tested beams has been investigated with observation on mid span deflection, failure mode and crack growth. Increase of the Tensile Reinforcement ratio results in more cracks but with lower height and width. The linear graphs between the applied load and corresponding deflection or curvature in reinforced HSC beams showed that the behaviour of these beams is elastic and any increase in the Tensile Reinforcement ratio results in an increase in the ultimate load too. The moment–curvature graph and load–deflection curve started with an initial elastic response followed by an inelastic behaviour that appears with a gradual decrease in stiffness till the ultimate moment is reached.
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ductility and strength assessment of hsc beams with varying of Tensile Reinforcement ratios
Structural Engineering and Mechanics, 2013Co-Authors: Mohammad Mohammadhassani, Meldi Suhatril, Mahdi Shariati, Farhad GhanbariAbstract:Nine rectangular-section of High Strength Concrete(HSC) beams were designed and casted based on the American Concrete Institute (ACI) code provisons with varying of Tensile Reinforcement ratio as (pmin, 0.2pb, 0.3pb, 0.4pb, 0.5pb, 0.75pb, 0.85pb, pb, 1.2pb). Steel and concrete strains and deflections were measured at different points of the beam\'s length for every incremental load up to failure. The ductility ratios were calculated and the moment-curvature and load-deflection curves were drawn. The results showed that the ductility ratio reduced to less than 2 when the Tensile Reinforcement ratio increased to 0.5pb. Comparison of the theoretical ductility coefficient from CSA94, NZS95 and ACI with the experimental ones shows that the three mentioned codes exhibit conservative values for low reinforced HSC beams. For over-reinforced HSC beams, only the CSA94 provision is more valid. ACI bending provision is 10 percent conservative for assessing of ultimate bending moment in low-reinforced HSC section while its results are valid for overreinforced HSC sections. The ACI code provision is non-conservative for the modulus of rupture and needs to be reviewed.
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Ductility and performance assessment of high strength self compacting concrete (HSSCC) deep beams: An experimental investigation
Nuclear Engineering and Design, 2012Co-Authors: Mohammad Mohammadhassani, Mohd Zamin Jumaat, Mohammed Jameel, Hamid Badiee, Arul M.s. ArumugamAbstract:Abstract The behavior of deep beams is significantly different from that of normal beams. Because of their proportions, deep beams are likely to have strength controlled by shear. This paper discusses the results of eight simply supported high strength self compacting concrete (HSSCC) deep beams having variation in ratio of web Reinforcement and Tensile Reinforcement. The deflection at two points along the beam length, web strains, Tensile bars strains and the strain at concrete surface are recorded. The results show that the strain distribution at the section height of mid span is nonlinear. Ductility decreased with increase in Tensile Reinforcement ratio. The effect of width of load point and the support point is more important than the effect of Tensile Reinforcement ratio in preventing premature failure. Load–deflection graphs confirm linear relationship up to 85% of the ultimate load for HSSCC over-Reinforcement web sections. The absorbed energy index increases with the increase in Tensile Reinforcement ratios.
Adelino V. Lopes - One of the best experts on this subject based on the ideXlab platform.
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FE modeling of inelastic behavior of reinforced high-strength concrete continuous beams
Structural Engineering and Mechanics, 2014Co-Authors: Sergio M.r. Lopes, Adelino V. LopesAbstract:A finite element model for predicting the entire nonlinear behavior of reinforced high-strength concrete continuous beams is described. The model is based on the moment-curvature relations pre-generated through section analysis, and is formulated utilizing the Timoshenko beam theory. The validity of the model is verified with experimental results of a series of continuous high-strength concrete beam specimens. Some important aspects of behavior of the beams having different Tensile Reinforcement ratios are evaluated. In addition, a parametric study is carried out on continuous high-strength concrete beams with practical dimensions to examine the effect of Tensile Reinforcement on the degree of moment redistribution. The analysis shows that the Tensile Reinforcement in continuous high-strength concrete beams affects significantly the member behavior, namely, the flexural cracking stiffness, flexural ductility, neutral axis depth and redistribution of moments. It is also found that the relation between the Tensile Reinforcement ratios at critical negative and positive moment regions has great influence on the moment redistribution, while the importance of this factor is neglected in various codes.
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Effects of the compressive Reinforcement buckling on the ductility of RC beams in bending
Engineering Structures, 2012Co-Authors: Adelino V. Lopes, Sergio M.r. Lopes, R.n.f. CarmoAbstract:Abstract This paper presents a study on the structural behavior of 15 reinforced concrete beams. The beams were 3 m long and the rectangular cross section measured 0.20 × 0.30 m 2 . They were subjected to two concentrated forces, applied at a third of the span until the failure occurred. The beams had different amounts of longitudinal and transverse Reinforcement and were divided into five series. Their strength, deformation and type of failure were analyzed. The main results are presented and discussed in terms of load-displacement, moment–curvature, ductility factor and plastic rotation capacity. In the light of the results it was concluded that beams with high Tensile Reinforcement ratios suffer premature failure due to the buckling of the compressive bars. These results indicate the importance of the stirrups spacing in RC beams. The influence of the Tensile Reinforcement ratio and the transverse Reinforcement on the plastic rotation capacity and on the general beam behavior was analyzed. This experimental study made it possible to define maximum values for ρ and minimum values for A sw / s to ensure a certain structural energy dissipation capacity.
R Jeffry - One of the best experts on this subject based on the ideXlab platform.
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EFFECT OF DIFFERENT CONFINEMENT SHAPES ON THE BEHAVOUR OF REINFORCED HSC BEAMS
2020Co-Authors: Hadi M.n.s., R JeffryAbstract:High strength concrete (HSC) provides high strength but lower ductility compared to normal strength concrete. This low ductility limits the benefit of using HSC in building safe structures. This means that a designer should be aware of limiting the amount of Tensile Reinforcement to prevent the brittle failure of concrete. Therefore the full potential of the use of steel Reinforcement cannot be achieved. This paper presents a method to prevent the brittle failure of concrete beams. Five beams made of HSC were cast and tested. The cross section of the beams was 200×300 mm, with a length of 4 m and a clear span of 3.6 m subjected to four-point loading, with emphasis placed on the midspan deflection. The first beam served as a reference beam. The remaining beams had different Tensile Reinforcement and the confinement shapes were changed to gauge their effectiveness in improving the strength and ductility of the beams. The compressive strength of the concrete was 85 MPa and the Tensile strength of the steel was 500 MPa and for the stirrups was 250 MPa. Results of testing the five beams proved that placing helixes with the right diameter and pitch in the compression zone of reinforced concrete beams improve their strength and ductility.
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The effect of confinement shapes on over-reinforced HSC beams.
Journal of Civil and Environmental Engineering, 2008Co-Authors: R Jeffry, Muhammad N S HadiAbstract:High strength concrete (HSC) provides high strength but lower ductility than normal strength concrete. This low ductility limits the benefit of using HSC in building safe structures. On the other hand, when designing reinforced concrete beams, designers have to limit the amount of Tensile Reinforcement to prevent the brittle failure of concrete. Therefore the full potential of the use of steel Reinforcement can not be achieved. This paper presents the idea of confining concrete in the compression zone so that the HSC will be in a state of triaxial compression, which leads to improvements in strength and ductility. Five beams made of HSC were cast and tested. The cross section of the beams was 200×300 mm, with a length of 4 m and a clear span of 3.6 m subjected to four-point loading, with emphasis placed on the midspan deflection. The first beam served as a reference beam. The remaining beams had different Tensile Reinforcement and the confinement shapes were changed to gauge their effectiveness in improving the strength and ductility of the beams. The compressive strength of the concrete was 85 MPa and the Tensile strength of the steel was 500 MPa and for the stirrups and helixes was 250 MPa. Results of testing the five beams proved that placing helixes with different diameters as a variable parameter in the compression zone of reinforced concrete beams improve their strength and ductility.
