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.

Experimental Study on Reinforcement of Failure Reinforced Concrete Beams

2013 ◽  
Vol 275-277 ◽  
pp. 1264-1267
Author(s):  
Qian Chen ◽  
Ling Yong Liu ◽  
Yang Jun Meng
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Epoxy Resin ◽  
Cross Section ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Carbon Cloth ◽  
Structural Failure

Through repair and reinforcement of breaking reinforced concrete beams by epoxy resin and carbon cloth, and its experiment, the crack and deformation and bearing capacity as well as ductility of such beams are obtained. Experimental results show that the ultimate bearing capacity of beams after reinforcement increased by 210%, the structure ductility fell by 170%, structural failure form is similar to failure in normal cross section.

Experimental Study on Reinforcement of Failure Reinforced Concrete Beams

2014 ◽  
Vol 578-579 ◽  
pp. 1266-1270
Author(s):  
Qiang Chen ◽  
Ling Yong Liu ◽  
Yang Jun Meng
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Epoxy Resin ◽  
Cross Section ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Carbon Cloth ◽  
Structural Failure

Through repair and reinforcement of breaking reinforced concrete beams by epoxy resin and carbon cloth, and its experiment, the crack and deformation and bearing capacity as well as ductility of such beams are obtained. Experimental results show that the ultimate bearing capacity of beams after reinforcement increased by 210%, the structure ductility fell by 170%, structural failure form is similar to failure in normal cross section.

Numerical Tracking of the Behavior of Repaired Reinforced Concrete Beams by CFRP Sheets against Shear

2020 ◽  
Vol 1002 ◽  
pp. 604-614
Author(s):  
Hayder Hussein H. Kammona ◽  
Muhammad Abed Attiya ◽  
Qasim M. Shakir
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Cfrp Sheets ◽  
Shear Span ◽  
Concrete Members ◽  
Suggested Technique ◽  
Cfrp Sheet ◽  
Failure Loads

This study simulates a procedure of rehabilitation of reinforced concrete beams with the aid of ANSYS 17 software. In this work, the BIRTH and DEATH procedure (in ANSYS) was adopted to model the post-repairing stage. This aspect has rarely been considered by previous studies that utilized a carbon fiber reinforced polymer (CFRP) sheet when retrofitting. To verify the suggested technique, six specimens were analyzed with two values of shear span-to-depth ratios (3 and 4) and three spaces of CFRP sheets (100mm, 150mm and 200mm). The effect of the repairing process on the structural performance of the retrofitted beam is also investigated.It is found that the suggested technique yielded a good agreement with the experimental results and the maximum differences in the failure loads between the numerical and experimental results were 10% and 4% for shear span-to-depth ratios of 3 and 4, respectively. It was also ascertained that upgrading reinforced concrete members within the early stages of loading showed a better enhancement in the loading capacity compared to upgrading reinforced concrete members close to the juncture of failure.

scholarly journals Guided Wave Propagation in Detection of Partial Circumferential Debonding in Concrete Structures

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2199 ◽  
Author(s):  
Beata Zima
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Wave Velocity ◽  
Guided Waves ◽  
Concrete Structures ◽  
Circular Cross Section ◽  
Guided Wave ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Average Wave

The following article presents results of investigating the damage detection in reinforced concrete beams with artificially introduced debonding between the rod and cover, using a non-destructive method based on elastic waves propagation. The primary aim of the research was to analyze the possible use of guided waves in partial circumferential debonding detection. Guided waves were excited and registered in reinforced concrete specimens with varying extents of debonding damage by piezoelectric sensors attached at both ends of the beams. Experimental results in the form of time–domain signals registered for variable extent of debonding were compared, and the relationships relating to the damage size and time of flight and average wave velocity were proposed. The experimental results were compared with theoretical predictions based on dispersion curves traced for the free rod of circular cross-section and rectangular reinforced concrete cross-section. The high agreement of theoretical and experimental data proved that the proposed method, taking advantage of average wave velocity, can be efficiently used for assessing debonding size in reinforced concrete structures. It was shown that the development of damage size in circumferential direction has a completely different impact on wave velocity than development of debonding length. The article contains a continuation of work previously conducted on the detection of delamination in concrete structures. The proposed relationship is the next essential step for developing a diagnostics method for detecting debondings of any size and orientation.

scholarly journals Design of reinforced concrete beams with steel fibers in the ultimate limit state

2018 ◽  
Vol 11 (5) ◽  
pp. 997-1024
Author(s):  
T. E. T. BUTTIGNOL ◽  
J. F. FERNANDES ◽  
T. N. BITTENCOURT ◽  
J. L. A. O. SOUSA
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Limit State ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Ultimate Limit State ◽  
Bending Tests

Abstract This paper carries out a design analysis of reinforced concrete beams with steel fibers following the fib Model Code 2010 (MC 2010) procedures. The values obtained from the design calculations are compared with the experimental results of reinforced concrete beams with 20kg/m3 and 60 kg/m3 of steel fibers submitted to four-point bending tests. In the first part, the procedures for the classification and characterization of the material are explained. The experimental results of three-point bending tests performed on notched steel fiber reinforced concrete (FRC) beams following EN 14651 procedures are described. Moreover, the characterization of the FRC beams according to MC 2010, are carried out. In the second part, the flexural design of reinforced concrete beams with steel fibers, according to MC 2010, is carried out. A sectional analysis is performed in order to obtain the moment-curvature and the force-vertical displacement curves. The theoretical values are compared with the experimental results. Besides, a linear statistic analysis by means of the Rule of Mixture is carried out in order to analyze the variation of the flexural capacity of the reinforced beams with different amounts of steel fibers. The results demonstrated that the design rules described in the MC 2010 are on the safe side. The flexural resistance of concretes with different amounts of fiber incorporation can be determined by the Rule of Mixture, which has shown a high correlation factor (R2) with the experimental values.

Flexural capacity and design of hybrid FRP-steel-reinforced concrete beams

2019 ◽  
Vol 23 (7) ◽  
pp. 1290-1304
Author(s):  
Yang Yang ◽  
Ze-Yang Sun ◽  
Gang Wu ◽  
Da-Fu Cao ◽  
Zhi-Qin Zhang
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Steel Reinforced Concrete ◽  
Reinforced Polymer ◽  
The Cross

This study presents a design method for hybrid fiber-reinforced-polymer-steel-reinforced concrete beams by an optimized analysis of the cross section. First, the relationships among the energy consumption, the bearing capacity, and the reinforcement ratio are analyzed; then, the parameters of the cross section are determined. Comparisons between the available theoretical and experimental results show that the designed hybrid fiber-reinforced-polymer-steel-reinforced concrete beams with a low area ratio between the fiber-reinforced polymer and the steel reinforcement could meet the required carrying capacity and exhibited high ductility.

Calculation of Flexural Capacity of High-Strength Reinforced Concrete Beams Strengthened with FRP

2011 ◽  
Vol 71-78 ◽  
pp. 815-817 ◽  
Author(s):  
Jiong Feng Liang ◽  
Ze Ping Yang ◽  
Zhi Ming Qiu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Engineering Application ◽  
High Strength ◽  
Correlation Equation ◽  
Reinforced Concrete Beams ◽  
Flexural Capacity ◽  
Different Types ◽  
Fiber Reinforce ◽  
Good Agreement

The mechanical properties of high-strength reinforced concrete beams strengthened with FRP ( fiber reinforce polymer) are further investigated theoretically including it s failure mechanism and loadability,based on earlier theoretical works on RC beams. And the correlation equation of flexural capacity on the cross section of high-strength reinforced concrete beams strengthened with FRP is deduced according to different types of failure.The correlation equation is shown to be in good agreement with the experimental results, which can be referred to engineering application.

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.

Effect of concrete carbonation on natural frequency of reinforced concrete beams

2016 ◽  
Vol 20 (3) ◽  
pp. 316-330 ◽  
Author(s):  
Liye Zhang ◽  
Limin Sun
Keyword(s):  
Reinforced Concrete ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Concrete Beams ◽  
Physicochemical Process ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Accelerated Carbonation ◽  
Concrete Carbonation ◽  
Damage In Concrete

We carried out an experimental investigation to study the influence of concrete carbonation on the natural frequency of simply supported reinforced concrete beams. A total of 10 reinforced concrete test beams and 12 concrete-carbonation test specimens were subjected to different accelerated carbonation stages for 0, 7, 14, 21, and 28 days. Modal tests were performed on reinforced concrete test beams after the accelerated carbonation stages. In order to reduce the effect of other factors on the modal tests, constant temperature, relative humidity, and boundary conditions of the test beams were maintained in the experimental process. The experimental results show a trend of the natural frequencies of reinforced concrete test beams to decrease with the increase in concrete-carbonation depths. With statistical analyses of experimental data, this study established the relationship between concrete-carbonation depths and natural frequencies. Fitting lines for the drop in natural frequencies and carbonation depths are obtained for the first four modal frequencies. Based on the analysis of the physicochemical processes of concrete carbonation, the main reason behind the drop in natural frequencies is the increase in mass after concrete carbonation. The percentage composition of increase in mass after complete carbonation is obtained based on the analysis of the physicochemical process. This analysis demonstrates part of the reason for the drop in natural frequencies and proves that the experimental results are reliable and credible. This study provides further insight into the use of modal parameters to assess damage in concrete structures in structural health monitoring.

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