Crack Analysis on Reinforced Concrete Beams Strengthened by Externally Prestressing Vertical Tensioning Method

2012 ◽  
Vol 204-208 ◽  
pp. 3104-3113
Author(s):  
Bo Wen Shi ◽  
Tian Wen Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Tension Zone ◽  
Stress Mode ◽  
Reinforced Beams ◽  
Internal Forces ◽  
Externally Prestressing ◽  
Resistance Equation

In this paper, seven reinforced concrete beams (two contrast beams and five externally reinforced beams) were tested. The crack regularity under different tension stresses was analyzed through experimental data. Taking the stress mode under pressure for the triangle area, in the tension zone in the shape of a trapezoid , the crack resistance equation of externally prestressing reinforced rectangle beam is derived from balance method of the internal forces and moment, and the results coincide with the experiment results well.

Strengthening of Reinforced Concrete Beams by Carbon Fiber Composites

2018 ◽  
Vol 931 ◽  
pp. 379-384
Author(s):  
Yuri V. Ivanov ◽  
Yuri F. Rogatnev ◽  
Igor I. Ushakov
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Carbon Fiber Composites ◽  
Limiting State ◽  
Reinforced Plastics ◽  
Reinforced Beams ◽  
The Given

The paper considers the results of the experimental study of the reinforced concrete beams strengthened by carbon fiber reinforced plastics (the CFRP). Eight reinforced concrete beams of the 80x160 mm section and 1500 mm designed span have been manufactured and tested. The influence of the number of the CFRP layers (strengthening power) on bearing capacity and rigidity under the static loading of beams in the thirds of the span has been studied. The results obtained indicate the increase in bearing capacity of the reinforced beams from 24% up to 55% and the increase in rigidity by 45% for the commonly adopted limiting state, i.e. achieving ultimate deformations in concrete of the compressed zone). The paper underlines the need for using anchor devices in the form of U-shaped binders to ensure the efficiency of the given method of strengthening.

scholarly journals Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyu Fu ◽  
Dawei Tong ◽  
Yuyang Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Internal Force ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Gradual Change ◽  
Concrete Cracking ◽  
Good Agreement

Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.

Research on Influences of the Coarse Aggregate Size on the Cracks of the Reinforced Beam

2012 ◽  
Vol 503-504 ◽  
pp. 832-836
Author(s):  
Hong Quan Sun ◽  
Jun Ding
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Fractal Theory ◽  
Aggregate Size ◽  
Reinforced Concrete Beams ◽  
Static Loads ◽  
Reinforced Beams ◽  
Maximum Crack

This paper gives the influences of the coarse aggregate size on the cracks of the beam with different aggregate sizes under static loads. The coarse aggregate sizes are ranked into three classes: small size (4.75mm ~ 19mm), big size (19mm ~ 37.5mm) and mixed size (4.75mm ~ 37.5mm). The developments of cracks of three reinforced concrete beams with the different of coarse aggregate sizes under the static loads are researched. The results show that under the action of the same loads, The reinforced concrete beams with the big aggregate size and mixed aggregate size have almost the same maximum crack width, while the maximum crack width of the beam with small aggregate size is less than formers. Using fractal theory, the fractal dimension of the cracks is studied. The result shows that the aggregate sizes have significant effect to the cracks on the reinforced beams.

scholarly journals Limiting Reinforcement Ratios for Hybrid GFRP/Steel Reinforced Concrete Beams

2021 ◽  
Vol 11 (1) ◽  
pp. 01-11
Author(s):  
Duy Phan Nguyen ◽  
Viet Quoc Dang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Equilibrium Equations ◽  
Steel Reinforced Concrete ◽  
Glass Fiber Reinforced ◽  
Load Carrying

In this work, a theoretical approach is proposed for estimating the minimum and maximum reinforcement ratios for hybrid glass fiber reinforced polymer (GFRP)/steel-reinforced concrete beams to prevent sudden and brittle failure as well as the compression failure of concrete before the tension failure of reinforcements. Equilibrium equations were used to develop a method for determining the minimum hybrid GFRP/steel reinforcement ratio. A method for determining the maximum hybrid GFRP/steel reinforcement ratio was also developed based on the equilibrium of forces of the balanced failure mode. For estimating the load-carrying capacity of concrete beams reinforced with hybrid GFRP/steel, less than the minimum and more than the maximum reinforcement ratio is recommended. Comparisons between the proposed expressions, experimental data, and available test results in the literature shows good agreement between the theoretical and experimental data, with a maximum discrepancy of 7%.

Deflection Calculation on Reinforced Concrete Beams Strengthened by Externally Prestressing Transverse Tensioning Method

2013 ◽  
Vol 671-674 ◽  
pp. 430-436
Author(s):  
Jin Jun Liu ◽  
Tian Wen Wang
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Large Error ◽  
Reinforced Concrete Beams ◽  
Secondary Effect ◽  
Test Results ◽  
Short Term ◽  
Secondary Load ◽  
Externally Prestressing ◽  
Good Agreement

Eight reinforced concrete beams (six externally reinforced and two contrast beams) were tested under primary or secondary load experiment. According to the test results, the existing specifications were applied to make calculations on short-term deflection which leaded to a large error. The secondary effect should be considered on calculating the deflection. Therefore, comparisons were made between the improved calculated value and test value on deflections of reinforced concrete beams strengthened by externally prestressed transverse tensioning method and they are in good agreement.

Flexural behaviour of ECC and ECC–concrete composite beams reinforced with hybrid FRP and steel bars

2021 ◽  
pp. 136943322110203
Author(s):  
Fang Yuan ◽  
Ren Hu
Keyword(s):  
Corrosion Resistance ◽  
Reinforced Concrete ◽  
Failure Modes ◽  
Concrete Beams ◽  
Steel Corrosion ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Flexural Behaviour ◽  
Reinforced Beams ◽  
Load Carrying

Owing to the good ductility of steel and high strength and excellent corrosion resistance of fibre-reinforced polymer (FRP), concrete beams reinforced with hybrid steel and FRP bars exhibit better ductility than FRP-reinforced concrete beams as well as higher load-carrying capacities and better corrosion resistance than steel-reinforced concrete beams. However, the inherent brittleness of concrete in tension results in steel corrosion because of wide cracks and accelerated fracture of FRP reinforcement because of crack-induced stress concentration. This study investigated the effects of ultra-high ductile engineered cementitious composites (ECCs) on the flexural behaviour of hybrid steel and FRP-reinforced beams. Six hybrid-reinforced beams with various reinforcement ratios, matrix types and ECC pouring positions were tested in four-point bending. The flexural behaviours of the beams in terms of failure modes, crack patterns and developments, load versus deformation relationships and ductility are discussed herein in detail. We observed that substituting ECC with concrete results in a higher load-carrying capacity and better ductility of the hybrid reinforced beams owing to the excellent characteristics of ECC materials. When a layer of ECC is poured in the tension zone, the average crack width and crack spacing along the beam decrease; therefore, the longitudinal reinforcements can be adequately protected.

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