An Efficient Method of Estimating Sediment Discharge in Rivers

Quantifying of sediment discharge with conventional measurement techniques is expensive and labor intensive. An efficient method that can estimate the average cross-sectional sediment concentration and discharge in a river channel by single-point sampling was developed. This method relies on the Chiu's velocity and sediment distribution models, which are based on a probability concept. The advantage of this approach compared to conventional methods is that the velocity and sediment concentration can be accurately estimated throughout the water depth, including the channel bed and water surface. This method requires determining the location of a vertical hereinafter is referred to as the y-axis, where the maximum velocity of the entire cross section occurs. The correlation between the mean sediment concentration on each vertical and the cross-sectional mean concentration is computed. It has been found that the optimal location of sediment sampling should be on y-axis at a point where sediment concentration is equal to the mean concentration on y-axis. A family of plots for selection of the sampling location was developed. Finally, a method based on Chiu's sediment transport model and data analysis was developed to estimate the mean sediment concentration in a channel section. This sediment concentration can be used to calculate the sediment discharge

Behavior of hybrid steel fiber reinforced high strength concrete

High strength concrete has higher strength but lower ductility. Inclusion of single type of fibers into concrete has been proven to improve the behavior of concrete to a limited extent. However, recently it was found that the behavior of concrete can be improved more with the addition of hybrid fiber i.e., a combination of different types of fiber. This paper presents the results of an experimental investigation on the behavior of Hybrid Steel Fibre Reinforced High Strength Concrete (HSFR-HSC). A total of eight cylinder specimens with 150 mm in diameter and 300 mm in height were cast and tested under uniaxial compression. Three different combinations of HSFR-HSC specimens and reference specimens without steel fibers were prepared. The first combination of HSFR-HSC included 1.5% Micro Steel (MS) fibers and 1% Deformed Steel (DS) fibers. The second combination included 1.5% MS fibers and 1.5% Hooked-end Steel (HS) fibers. The third combination included 1% DS fibers and 1.5% HS fibers. The experimental results showed that the addition of hybrid steel fibers improved the strength and ductility of high strength concrete compared to the reference specimens. The results also showed that the specimens reinforced with different hybrid steel fibers failed in a ductile manner, while the reference specimens failed in a brittle manner

Models for predicting the axial compressive strength of steel fibre reinforced normal and high strength concrete square columns

Over the last three decades, fibre has been commonly used in reinforced concrete (RC) columns to enhance their strength and ductility. In the available studies on Steel Fibre Reinforced Concrete (SFRC) columns, axial compressive strength of the columns is expressed as functions of unconfined concrete compressive strength and the lateral confinement pressure. In this study, available experimental investigation results of the axial compressive strength of SFRC square columns have been compiled. This study also proposes axial compressive strength models of the SFRC square columns using artificial neural network (ANN). In the proposed models, axial compressive strength of SFRC columns has been expressed as functions of unconfined concrete compressive strength (fc\u27), confinement pressure due to lateral reinforcement (fle) and confinement pressure due to the action of steel fibres (flb). The results of the proposed ANN strength models match very well with the available experimental results

Performance of high strength concrete columns reinforced with hybrid steel fiber under different loading conditions

The strength and ductility of high strength concrete columns improve with the addition of steel fiber. This paper reports the behavior of circular High Strength Concrete (HSC) columns reinforced with Hybrid Steel Fibers (HSF) under different loading conditions. In this study, HSF consisted of a combination of macro steel fibers and micro steel fibers. A total of eight circular specimens of 205 mm diameter and 800 mm height were cast and tested. All specimens were reinforced with same amount of steel reinforcements. The specimens were divided into two groups of four specimens. Group RC (reference group) contained no steel fibers. Group HSF (hybrid steel fibers) contained 2.5% by volume of HSF. From each group one specimen was tested under concentric loading, one under 25 mm eccentric loading, one under 50 mm eccentric loading, and one under four-point loading. The results showed that the specimens reinforced with HSF achieved higher strength and ductility compared to RC specimens under different loading conditions. It was also observed that the presence of HSF delayed the spalling of the concrete cover

Behaviour of high strength concrete reinforced with different types of steel fibres

This paper reports the results of an experimental investigation on the behaviour of High Strength Concrete (HSC) reinforced with different types of steel fibre (copper-coated micro steel fibres, deformed macro steel fibre and hybrid steel fibre). A total of 40 cylindrical specimens with 100 mm diameter and 200 mm height were cast and tested for compressive and split tensile strengths. Three groups of steel fibre reinforced HSC specimens were prepared. The first group included 2, 3, and 4% by volume of copper-coated micro (CM) steel fibre; the second group included 1, 2 and 3% by volume of deformed macro (DM) steel fibre; and the third group included 1.5% (1% CM + 0.5% DM), 2.5% (1.5% CM + 1% DM), and 3.5% (2% CM + 1.5% DM) by volume of hybrid (H) steel fibre. Plain HSC specimens without steel fibre were also prepared. The experimental results showed higher improvements in the compressive and split tensile strengths of the HSC with the inclusion of 3, 2, and 2.5% by volume of CM, DM and H steel fibres, respectively, compared to the plain HSC

Behavior of steel fiber-reinforced high-strength concrete columns under different loads

This paper reports the results of an experimental investigation program on the behavior of high-strength concrete (HSC) columns reinforced with micro, macro, and hybrid steel fibers. The specimens were tested under concentric, 25 and 50 mm (0.98 and 1.96 in.) eccentric axial and four-point bending. The main variables were the type, volume content and aspect ratio of steel fibers. Sixteen circular specimens of 205 mm (8.07 in.) diameter and 800 mm (31.49 in.) height were cast and tested. The specimens were reinforced with the same amount of longitudinal and helical steel reinforcements. It was found that the inclusion of either micro or hybrid steel fibers into HSC enhanced the strength and ductility of the specimens under eccentric axial loads. The results also showed that the addition of macro steel fibers into HSC enhanced the ductility but reduced the strength of the specimens compared to the specimens without steel fibers