scholarly journals Moment-Curvature Behaviors of Concrete Beams Singly Reinforced by Steel-FRP Composite Bars

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Zeyang Sun ◽  
Yang Yang ◽  
Wenlong Yan ◽  
Gang Wu ◽  
Xiaoyuan He
Keyword(s):  
Bearing Capacity ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Frp Composite ◽  
Steel Bar ◽  
Before And After ◽  
Frp Bar ◽  
Deformation Ability ◽  
Effective Depth ◽  
The Moment

A steel-fiber-reinforced polymer (FRP) composite bar (SFCB) is a kind of rebar with inner steel bar wrapped by FRP, which can achieve a better anticorrosion performance than that of ordinary steel bar. The high ultimate strength of FRP can also provide a significant increase in load bearing capacity. Based on the adequate simulation of the load-displacement behaviors of concrete beams reinforced by SFCBs, a parametric analysis of the moment-curvature behaviors of concrete beams that are singly reinforced by SFCB was conducted. The critical reinforcement ratio for differentiating the beam’s failure mode was presented, and the concept of the maximum possible peak curvature (MPPC) was proposed. After the ultimate curvature reached MPPC, it decreased with an increase in the postyield stiffness ratio (rsf), and the theoretical calculation method about the curvatures before and after the MPPC was derived. The influence of the reinforcement ratio, effective depth, and FRP ultimate strain on the ultimate point was studied by the dimensionless moment and curvature. By calculating the envelope area under the moment-curvature curve, the energy ductility index can obtain a balance between the bearing capacity and the deformation ability. This paper can provide a reference for the design of concrete beams that are reinforced by SFCB or hybrid steel bar/FRP bar.

scholarly journals Mechanical Properties of Steel-FRP Composite Bars under Tensile and Compressive Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Zeyang Sun ◽  
Yu Tang ◽  
Yunbiao Luo ◽  
Gang Wu ◽  
Xiaoyuan He
Keyword(s):  
Failure Modes ◽  
Flexural Rigidity ◽  
Compressive Loading ◽  
Concrete Structures ◽  
Frp Composite ◽  
Steel Bar ◽  
Calculated Stress ◽  
Frp Bar ◽  
Large Length ◽  
Ordinary Steel

The factory-produced steel-fiber reinforced polymer composite bar (SFCB) is a new kind of reinforcement for concrete structures. The manufacturing technology of SFCB is presented based on a large number of handmade specimens. The calculated stress-strain curves of ordinary steel bar and SFCB under repeated tensile loading agree well with the corresponding experimental results. The energy-dissipation capacity and residual strain of both steel bar and SFCB were analyzed. Based on the good simulation results of ordinary steel bar and FRP bar under compressive loading, the compressive behavior of SFCB under monotonic loading was studied using the principle of equivalent flexural rigidity. There are three failure modes of SFCB under compressive loading: elastic buckling, postyield buckling, and no buckling (ultimate compressive strength is reached). The increase in the postyield stiffness of SFCB rsf can delay the postyield buckling of SFCB with a large length-to-diameter ratio, and an empirical equation for the relationship between the postbuckling stress and rsf is suggested, which can be used for the design of concrete structures reinforced by SFCB to consider the effect of reinforcement buckling.

scholarly journals Experimental Analysis of the Strengthening of Reinforced Concrete Beams in Shear Using Steel Plates

2018 ◽  
Vol 3 (4) ◽  
pp. 52 ◽  
Author(s):  
Marília Batti ◽  
Bruno Silva ◽  
Ângela Piccinini ◽  
Daiane Godinho ◽  
Elaine Antunes
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Point Load ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Short Term ◽  
Before And After ◽  
Underlying Causes ◽  
Structural Adhesive

In some situations, it is necessary to strengthen or rehabilitate a structure in the short term, but before doing so, a critical analysis of the underlying causes is required to find the best technique to solve the problem. The structural strengthening is used to increase an element’s ability to resist a stress when it no longer meets the original conditions or new necessities of use due to faults, deterioration, thermal variations, and lack of maintenance. The present article aims to evaluate the strengthening of reinforced concrete beams with 0.75 mm thick SAE 1020 steel plates bonded with epoxy-based structural adhesive. The steel plates were attached to the sheared area before and after the beams were taken to the breaking point load. According to the results, it was possible to conclude the effectiveness of the strengthening applied to healthy beams that had its bearing capacity increased up to 50%. The beam that was strengthened after the shear, with a fissure that was restored with epoxy-based structural adhesive, had its load bearing capacity increased by 49.2%. The beams with fissures that were filled with mortar had their bearing capacity decreased by 58.70% if compared with the reference beams, and thus they presented an unsatisfactory performance.

scholarly journals A SHORT-TERM DEFORMATION ANALYSIS METHOD OF FLEXURAL REINFORCED CONCRETE MEMBERS

2011 ◽  
Vol 3 (3) ◽  
pp. 112-122
Author(s):  
Rokas Girdžius ◽  
Gintaris Kaklauskas ◽  
Renata Zamblauskaitė ◽  
Ronaldas Jakubovskis
Keyword(s):  
Reinforced Concrete ◽  
Reinforcement Ratio ◽  
Deformation Analysis ◽  
Analysis Method ◽  
Modulus Ratio ◽  
Short Term ◽  
Tension Stiffening ◽  
Eurocode 2 ◽  
Effective Depth ◽  
The Moment

The deformation analysis of cracked reinforced concrete (RC) members is not straightforward and often controversial. The main difficulties arise from the complex structure of concrete matrix, different mechanical properties of concrete and reinforcement, the creep and shrinkage of concrete and tension stiffening. The latter effect is related to intact concrete and reinforcement interaction between cracks. Tension stiffening effect has a significant influence on the results of a shortterm deformation analysis of RC members. The present research is aimed at deriving tension-stiffening relationship in accordance with the provisions of the Eurocode 2 technique. Using the inverse technique proposed by the second author, tension-stiffening constitutive laws were derived from the moment-curvature diagrams of RC beams calculated by Eurocode 2. The diagrams were calculated for a number of RC sections having a different amount of tensile reinforcement, the grade of concrete, effective depth and a modulus of steel elasticity. For the above model parameters, 450 moment-curvature diagrams were generated. For each of them, tension-stiffening relationships were obtained. The performed regression analysis led to analytical tension – stiffening relationship, which takes into account the reinforcement ratio, modulus ratio and concrete grade. A simplified short-term deformation analysis method of flexural RC members has been also proposed. This method is based on a bi-linear moment-curvature diagram: elastic and cracked parts. For the cracked part of the moment-curvature diagram, coefficient γ was introduced, which deals with the degradation of stiffness after cracking. An analytical expression was proposed for calculating coefficient γ, which takes into account the effective depth of the beam, reinforcement ratio and modulus ratio. A statistical verification of the proposed models has shown that a good agreement between calculated and experimental results was obtained at service loadings.

Size effect on shear strength of reinforced concrete beams with tension reinforcement ratio

2016 ◽  
Vol 20 (4) ◽  
pp. 582-594 ◽  
Author(s):  
Chan-Yu Jeong ◽  
Hyeong-Gook Kim ◽  
Sang-Woo Kim ◽  
Kang-Seok Lee ◽  
Kil-Hee Kim
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Size Effect ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Shear Tests ◽  
Effective Depth ◽  
Compressive Strength Of Concrete ◽  
Experimental Researches

It is well known that shear stress at peak of reinforced concrete beams decreases with increasing effective depth. Thus, several existing design codes and models have included various forms of formulas considering the size effect on shear strength of reinforced concrete beams; however, past experimental researches show that tension reinforcement ratio is also associated with the shear strength of reinforced concrete beams. To examine the effect of tension reinforcement ratio and effective depth on shear strength of reinforced concrete beams, this study has conducted experiments in which the effective depth (150, 300, 500, and 780 mm) and tension reinforcement ratio (1%, 2%, and 3%) are employed as variables. Besides, a formula for the shear strength considering both variables is proposed based on data samples collected from the present experiment and previous research. The proposed formula gives predictions comparable to the results of existing shear tests. Furthermore, rational predictions are made for effective depth of beams, compressive strength of concrete, shear span-to-depth ratio, and even tension reinforcement ratio exceeding 3%.

Experimental Study on Flexural Bearing Capacity of Reinforced Ceramsite Concrete Beam

2011 ◽  
Vol 366 ◽  
pp. 253-257
Author(s):  
Wei Jun Yang ◽  
Zheng Bo Pi ◽  
Zhen Lin Mo
Keyword(s):  
Bearing Capacity ◽  
Concrete Beam ◽  
Failure Modes ◽  
Concrete Beams ◽  
Cement Mortar ◽  
Reinforced Concrete Beams ◽  
Ordinary Concrete ◽  
Steel Bar ◽  
Steel Bars ◽  
Flexural Bearing Capacity

In order to investigate the flexural bearing capacity of reinforced ceramic concrete beams, static loading experiments were carried out. 10 ceramic reinforced concrete beams and 2 non-reinforced ceramic concrete with different steel ratios, cover thicknesses and bar diameters were fabricated. The gauges of concrete was arraged on the surfaces of section in mid-span and and steel gauges was arraged on the surfaces of steel bars. The loading device was consisted of a 200kN hydraulic jack, a distributive girder and reaction frame while the dial indicators was arraged in supports and mid-span. The strain of concrete and steel bar in different loading along with the crack,yield and utimate of load were recorded .It found that the stress-strain law, crack extension regularity , failure modes of specimens was similar to the ordinary concrete beams and the current procedures formulas about flexural bearing capacity is reliability. It also found that both ceramic aggregate and cement mortar were crushed for the perfectly bonding of the interface and the strength of aggregate was to be fully utilized.

Application of Equal Strength Substitution Method on Concrete Beams Strengthened with Steel Plates

2011 ◽  
Vol 368-373 ◽  
pp. 2341-2345
Author(s):  
Hong Liang Zuo ◽  
Chao Zhuang ◽  
Lin Lin Zhu
Keyword(s):  
Concrete Beams ◽  
Rectangular Cross Section ◽  
Reinforcement Ratio ◽  
Steel Plates ◽  
Calculation Methods ◽  
Substitution Method ◽  
Application Range ◽  
Equal Strength ◽  
The Moment ◽  
Relationship Of

To research the applicability of equal strength substitution method applied to concrete beams with steel plates, the effects on application range of equal strength substitution method by the initial reinforcement ratio and the strengthened moment design value are discussed．In this paper, the calculation methods of equivalent substitution and Design Code for Strengthening Concrete Structure are adopted to calculate five kinds of single-reinforced rectangular cross-section concrete beams of typical section size by adjusting the initial reinforcement ratio and the strengthened moment design value．The dosage of steel plates is obtained through the comparison of the equal strength substitution and code calculation methods, which is used to obtain the relationship of initial reinforcement ratio, the area ratio of steel plates calculated by the equal strength substitution and code calculation methods and the moment ratio of strengthened and initial ultimate moment． The result shows that equal strength substitution method is not applicable universally, which is feasible only within the scope of certain．

scholarly journals Test and Evaluation of the Flexural Properties of Reinforced Concrete Beams with 100% Recycled Coarse Aggregate and Manufactured Sand

Buildings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 420
Author(s):  
Changyong Li ◽  
Tongsheng Liu ◽  
Hao Fu ◽  
Xiaoyan Zhang ◽  
Yabin Yang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Crack Width ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Cracking Resistance ◽  
Manufactured Sand ◽  
Recycled Coarse Aggregate

Although studies have been performed on the recycled aggregate made of waste concrete for the production of new concrete, the new concrete with 100% recycled coarse aggregate and manufactured sand (abbreviated as RAMC) still needs to be researched for structural applications. In this paper, an experimental study was performed on seven groups, including fourteen reinforced RAMC beams under the simply supported four-point loading test, considering the factors of the strength of RAMC and the reinforcement ratio of longitudinal tensile rebars. Based on the test results, the cracking resistance, the bearing capacity, the crack width, the flexural stiffness and the mid-span deflection of reinforced RAMC beams in bending are discussed and examined by using the formulas of conventional reinforced concrete beams. Results show that an obvious effect of reinforcement ratio was present, while less so was that of the strength of RAMC. With the comparison of predicted values by the formulas of conventional reinforced concrete beams, the reinforced RAMC beams decreased cracking resistance by about 20%, increased crack width by about 15% and increased mid-span deflection by about 10%, although the same bearing capacity can be reached. The results directly relate to the lower tensile strength of RAMC which should be further improved.

scholarly journals Investigation of ANN architecture for predicting shear strength of fiber reinforcement bars concrete beams

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0247391
Author(s):  
Quang Hung Nguyen ◽  
Hai-Bang Ly ◽  
Thuy-Anh Nguyen ◽  
Viet-Hung Phan ◽  
Long Khanh Nguyen ◽  
...  
Keyword(s):  
Shear Strength ◽  
Modulus Of Elasticity ◽  
Concrete Beams ◽  
Beam Width ◽  
Reinforcement Ratio ◽  
Shear Reinforcement ◽  
Ann Model ◽  
Experimental Database ◽  
Frp Reinforcement ◽  
Effective Depth

In this paper, an extensive simulation program is conducted to find out the optimal ANN model to predict the shear strength of fiber-reinforced polymer (FRP) concrete beams containing both flexural and shear reinforcements. For acquiring this purpose, an experimental database containing 125 samples is collected from the literature and used to find the best architecture of ANN. In this database, the input variables consist of 9 inputs, such as the ratio of the beam width, the effective depth, the shear span to the effective depth, the compressive strength of concrete, the longitudinal FRP reinforcement ratio, the modulus of elasticity of longitudinal FRP reinforcement, the FRP shear reinforcement ratio, the tensile strength of FRP shear reinforcement, the modulus of elasticity of FRP shear reinforcement. Thereafter, the selection of the appropriate architecture of ANN model is performed and evaluated by common statistical measurements. The results show that the optimal ANN model is a highly efficient predictor of the shear strength of FRP concrete beams with a maximum R2 value of 0.9634 on the training part and an R2 of 0.9577 on the testing part, using the best architecture. In addition, a sensitivity analysis using the optimal ANN model over 500 Monte Carlo simulations is performed to interpret the influence of reinforcement type on the stability and accuracy of ANN model in predicting shear strength. The results of this investigation could facilitate and enhance the use of ANN model in different real-world problems in the field of civil engineering.

scholarly journals A Model of the Moment Curvature Relation for RC Beams Strengthened with Prestressed CFRP Laminates

2019 ◽  
Vol 65 (4) ◽  
pp. 217-228
Author(s):  
J. Korentz
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Cfrp Laminates ◽  
Before And After ◽  
The Moment

AbstractThe paper presents an analysis of the behaviour of bent reinforced concrete beams strengthened with CFRP laminates fixed with adhesive before and after unloading, and more importantly, an analysis of the work of reinforced concrete beams strengthened with pre-stressed CFRP laminates fixed with adhesive. The analyses were based on a moment-curvature model prepared by the author for reinforced concrete beams strengthened under load with pre-stressed CFRP laminates. The model was used to determine the effect of compression with CFRP laminates and their mechanical properties on the effectiveness of strengthening the reinforced concrete beams analysed in this study.

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