EFFECT OF CORROSION LONGITUDINAL STEEL BARS ON THE FLEXURAL STRENGTH OF RC BEAMS

2021 ◽  
Vol 28 (2) ◽  
pp. 44-53
Author(s):  
Noor Mahmood ◽  
Assim Lateef
Keyword(s):  
Concrete Beams ◽  
Concrete Strength ◽  
Corrosion Process ◽  
Rc Beams ◽  
Cross Sectional ◽  
Flexural Failure ◽  
Steel Bars ◽  
Major Parameter ◽  
Mode Of Failure ◽  
Concentrated Loading

The main objective of this research is to investigate the effect of corroded steel bars on the ultimate flexural capacity of reinforcement concrete beams. The experimental work consists of four RC beams with dimensions (150×200×1200) mm tested under two-point concentrated loading. The major parameter of the current research is corrosion period (5,10,20) days. The amount of longitudinal and transverse reinforcement, concrete strength and, the other parameters were kept constant for all samples. The comparisons between specimens are based on the visual cracking loads, ultimate loads, deflection, cracks pattern and mode of failure. Results showed that visual first cracking load, and ultimate loads of corroded RC beams were decreased with increase corrosion durations relative to the control beam as a result of the corrosion process. The mode of failure was flexural failure for all specimens. Corrosion caused decreasing percentage in weight of steel bars and cross-sectional area of longitudinal steel bars. This percent increased as exposure time to corrosion process increased by 8.5% and 28.39% for 20 days respectively.

Laboratory Fast Corrosion Test of Plain Steel Bars in Concrete Beams

2012 ◽  
Vol 535-537 ◽  
pp. 1803-1806
Author(s):  
Shun Bo Zhao ◽  
Peng Bing Hou ◽  
Fu Lai Qu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Numerical Models ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Uniform Corrosion ◽  
Pure Bending ◽  
Accelerated Corrosion ◽  
Steel Bars ◽  
Bending Length

An experimental study was carried out to examine the non-uniform corrosion of plain steel bars in reinforced concrete beams partially placed in 5% sodium chloride solution under conditions of accelerated corrosion. 4 reinforced concrete beams with different concrete strength were made. The crack distributions of the beams due to pre-loads and expansion of corrosion product, and the sectional corrosion characteristics of plain steel bars are described in detail. The sectional area loss relating to mass loss and change along pure bending length of the beams are discussed. These can be used as the basis of test for further studies to build the numerical models of serviceability of corroded reinforced concrete beams.

scholarly journals Experimental Study and Reliability Analysis of Flexural Capacity of RC Beams Reinforced with 600 MPa Grade Steel

2020 ◽  
Vol 2020 ◽  
pp. 1-26
Author(s):  
Xianhua Yao ◽  
Yulong Zhang ◽  
Junfeng Guan ◽  
Lielie Li ◽  
Haichao Liu ◽  
...  
Keyword(s):  
Yield Strength ◽  
Reliability Analysis ◽  
High Strength Steel ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Flexural Capacity ◽  
Steel Bars ◽  
Design Values ◽  
Grade Steel

Flexural capacity of beams reinforced with 400 or 500 MPa grade steel can be accurately estimated by using equations provided in design codes. Recently, 600 MPa grade steel has evolved in the construction industry, and the applicability of existing equations for this grade of steel should be verified by performing experimental investigation. By conducting tests on concrete beams reinforced with 600 MPa grade high-strength steel, this study investigates the flexural performance for different concrete strength grades and different reinforcement ratios. Flexural capacities of concrete beams reinforced with 400 MPa, 500 MPa, and 600 MPa grade steel are analyzed based on equations in various codes and based on experimental studies in the literature. Furthermore, this study performs reliability analysis and verifies the three design values of 600 MPa grade steel yield strength in relation to the experimental performance and recommends the appropriate design values of 600 MPa grade steel yield strength. Research results show that when the measured values of yield strength of the steel bars and concrete strength are used, the ratio of the measured failure moment value to the calculated value for various beams based on different codes is nearly 1.0, demonstrating the high degree of fitting. Finally, the reliability analysis shows that the design yield strength of the 600 MPa grade high-strength steel bars should be taken as 520 MPa.

scholarly journals Performance of Concrete Beams Reinforced with Various Ratios of Hybrid GFRP/Steel Bars

2020 ◽  
Vol 6 (9) ◽  
pp. 1652-1669
Author(s):  
Phan Duy Nguyen ◽  
Vu Hiep Dang ◽  
Ngoc Anh Vu
Keyword(s):  
Failure Modes ◽  
Concrete Beams ◽  
Peak Load ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Deformation Model ◽  
Rc Beams ◽  
Linear Deformation ◽  
Crack Patterns ◽  
Steel Bars

This paper aims to study the flexural behavior of concrete beams reinforced with hybrid combinations of GFRP/steel bars. To this purpose an experimental program was carried out on four concrete beams reinforced with Glass Fiber Reinforced Polymer (GFRP) and twelve hybrid GFRP/steel Reinforced Concrete (RC) beams. Flexural behavior of the tested beams such as stages of response, failure modes, crack patterns, stiffness, toughness and ductility were analyzed. The experimental results showed that depending on GFRP/steel reinforcement configurations, the behavior of hybrid GFRP/steel RC beams undergoes three or four stages, namely: pre-cracking stage; after concrete cracking and before steel yielding; post-yield stage of the steel bar until peak load and failure stage. Totally six failure modes of hybrid RC beams are reported depending on reinforcement rations and configuration. The effect of reinforcement configuration and ratio of GFRP to steel (ρg) on the crack patterns, stiffness, ductility and toughness of hybrid RC beams are significant. Based on the non-linear deformation model, an analytical model has been developed and validated to determine the steel yielding moment and ultimate moment of hybrid GFRP/steel RC beams. It could be seen that the experimental values were in good agreement with the predicted values.

scholarly journals The Attitude of Load-Deflection for Concrete Beams with Polymer Reinforcement

2019 ◽  
Vol 26 (4) ◽  
pp. 32-37
Author(s):  
Ahmed Saadon ◽  
Abdulnasser Abbas ◽  
Ali Khalaf
Keyword(s):  
Compressive Strength ◽  
Experimental Test ◽  
Ultimate Load ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Control Beam ◽  
Steel Bars ◽  
Conservative Values ◽  
Frp Bars

In this research, the load-deflection behavior is explored for concrete beams reinforced with FRP bars (polymer reinforcement). An experimental test is done for a total of five beams subjected to 4-point loading. The tested specimens are of dimensions; 2100 mm (length), 200 mm (width) and 300 mm (depth), while the used compressive strength for concrete is f’c = 60 MPa. Four beams were longitudinally reinforced by various CFRP rebar numbers, and the last beam was reinforced only by steel bars as control beam. Relationships for load-deflection were drawn and the influence of several factors was debated on this relationship. It was exhibited that the failure of FRP reinforced samples was generally ruled by the concrete strength. When the ratio of reinforcement rising by 50%, 100% and 150%, the ultimate load increased by 15%, 29% and 38%, respectively, while the recorded deflection at ultimate load decreased by 7%, 16% and 24%, respectively. For the ultimate load of the studied beams, outcomes exhibited that the equations of the American code ACI 440.1R give very close values with the test values, while they give very conservative values to the deflection at ultimate load which are smaller than the test values by about (37%-45%)

Flexural ductility of reinforced concrete beams with lap-spliced bars

2014 ◽  
Vol 41 (7) ◽  
pp. 594-604 ◽  
Author(s):  
Mehrollah Rakhshanimehr ◽  
M. Reza Esfahani ◽  
M. Reza Kianoush ◽  
B. Ali Mohammadzadeh ◽  
S. Roohollah Mousavi
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Transverse Reinforcement ◽  
Rc Beams ◽  
Flexural Ductility ◽  
Ductility Ratio ◽  
Strength And Ductility

In this paper, the flexural ductility of lap-spliced reinforced concrete (RC) beams is experimentally investigated. Twenty-four specimens were designed and manufactured for laboratory experiments. Concrete compressive strength, amount of transverse reinforcement over the splice length, and the diameter of longitudinal bars were selected as the main variables. The ductility of tested specimens is evaluated based on a previously defined ductility ratio. Results show that concrete strength and amount of transverse reinforcement over the splice have major effects on ductility. With an appropriate amount of transverse reinforcement, a satisfactory ductility response for different concrete strengths can be obtained. The CSA-A23.3-04 Standard provisions on bond strength and ductility of lap-spliced RC beams are evaluated and discussed. This study shows that the provisions in predicting the bond strength of lap-spliced concrete beams are adequate but may not achieve a satisfactory performance for ductility. An equation is proposed to achieve the appropriate ductility.

scholarly journals EXPERIMENTAL LOAD-DRIFT RELATIONS OF CONCRETE BEAM REINFORCED AND CONFINED WITH HIGH-STRENGTH STEEL BARS UNDER REVERSED CYCLIC LOADING

2021 ◽  
Vol 11 (4) ◽  
pp. 56-69
Author(s):  
Retno Anggraini ◽  
Tavio Tavio ◽  
Gusti Putu Raka ◽  
Agustiar Agustiar
Keyword(s):  
Reinforced Concrete ◽  
High Strength Steel ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Steel Bars ◽  
Normal Strength

High-strength steel bars have different characteristics from normal-strength steel bars. Thus, the use of high-strength steel bars still needs to be investigated further before it can be used confidently in concrete structures. In the design, a reinforced concrete beam should also have enough ductility besides its loading capacity. One of the indicators identifies that a structure has sufficient ductility is its ability to maintain the load steadily due to progressive deformation. This paper presents the test results of three reinforced concrete beams designed with concrete strength (fc) of 30 MPa. Two different yield strengths (fy) of longitudinal and transverse reinforcements were used, namely, 420 and 550 MPa. The cross-sectional dimensions of the beams were 200  300 mm with a total span of 2000 mm and a rigid stub at the midspan. The beams were simply supported by double rollers at their tops and bottoms. These special supports were located at both ends of the beams. The load applied at the midspan of the beam through the rigid stub with the displacement control. The loading pattern protocol by the drift was set from 0 to 5.5 percent. Based on the test results, it can be seen that the beams with high-strength steel bars could achieve a higher load capacity than the beams with normal-strength steel bars. On the other hand, the beams with high-strength steel bars produced lower deflection than the beams with normal-strength steel bars. Furthermore, it can be concluded that all the beams could withstand the minimum required of 3.5 percent. None of the beams indicated brittle failures. All of the beams could survived until the end of the cycles at a drift of 5.5 percent. This condition indicates that the reinforced concrete beams with higher-strength reinforcement (fy of 550 MPa) could also maintain their load capacities under large deformation beyond the first yielding of the longitudinal steel bars.

An analytical approach towards determining the strength of FRP-reinforced/prestressed concrete beams

2002 ◽  
Vol 29 (2) ◽  
pp. 301-315 ◽  
Author(s):  
Sameh R Salib ◽  
George Abdel-Sayed ◽  
Nabil Grace
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Research Work ◽  
Longitudinal Direction ◽  
Design Guidelines ◽  
Fiber Reinforced Polymers ◽  
Experimental Program ◽  
Premature Failure ◽  
Mode Of Failure

Non-corrosive fiber-reinforced polymers (FRP) are becoming a desirable replacement to steel bars in reinforcing/prestressing concrete structures. However, the difference between the two materials is not only related to the properties in the longitudinal direction of the bars as most of the current research work and design guidelines are concerned with. The properties in the transverse direction of the bars have basic differences, which may influence the beam strength and its mode of failure. This paper presents a comprehensive analytical modeling for evaluating the strength of concrete beams reinforced and (or) prestressed with FRP bars and the corresponding mode of failure. It takes into account significant parameters such as the crack path geometry, the crack width, and the properties of the bars in both longitudinal and transverse directions. The proposed analysis identifies any premature failure of beam due to the dowel failure of FRP reinforcement and determines the contribution of stirrups, if any, based on the number and actual tensile strain of the stirrups crossing the failure crack. A good agreement has been observed between the results of the developed model and the results of an experimental program conducted at the University of Windsor, as well as other published experimental programs.Key words: ACM, FRP, cracks, dowel action, reinforced concrete, strength.

scholarly journals Influence of Crack Width on Chloride Penetration in Concrete Subjected to Alternating Wetting–Drying Cycles

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3801
Author(s):  
Jun Lai ◽  
Jian Cai ◽  
Qing-Jun Chen ◽  
An He ◽  
Mu-Yang Wei
Keyword(s):  
Crack Width ◽  
Chloride Concentration ◽  
Rc Beam ◽  
Rc Beams ◽  
Cross Sectional ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Steel Bar ◽  
Steel Bars ◽  
Average Loss

To investigate the durability of reinforced concrete (RC) beams under the combined actions of transverse cracks and corrosion, corrosion tests were conducted on a total of eight RC beams with different water–cement ratios and cracking states. The effects of the transverse crack width, water–cement ratio, and the length of the wetting–drying cycle on the distribution of the free chloride concentration, the cross-sectional loss of the tensile steel bars, and the chloride diffusion coefficient are analyzed. The results show that the widths of the transverse crack and the water–cement ratio of concrete greatly affected the chloride profile and content of the RC beam specimens. Specifically, the chloride contents in all the cracked RC beams at the depth of the steel bar exceeded the threshold value of 0.15%. As the width of the cracks increased, the chloride concentration and penetration of the cracked concrete beam increased. However, the chloride concentration at the reinforcement position did not seem to be obviously affected by increasing the wetting–drying cycles from 182 days to 364 days. Moreover, the decrease of the water–cement ratio effectively inhibited the penetration of chloride ions in the RC beam specimens. In terms of the cross-sectional loss of the steel bars, the average loss of the steel bar increases with increasing crack width for the beams with 182-day cycles, while the effect of crack width on the average loss is not as noticeable for the beams with 364-day cycles. Finally, a model is proposed to predict the relationship between the crack width influence coefficient, μ, and the crack width, w, and this model shows good agreement with the experimental results.

Research on Fracture of FRP Reinforced Concrete Beams

2011 ◽  
Vol 201-203 ◽  
pp. 2931-2934
Author(s):  
Yan Feng Feng ◽  
Tian Hong Yang ◽  
Hua Wei ◽  
You Fa Gu ◽  
Hai Jun Wang
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Flexural Failure ◽  
Crushed Concrete ◽  
Frp Reinforcement ◽  
Fracture Performance ◽  
Test Result

With technology of FRP reinforcement concrete beams is applied in domain of the civil engineering, it attracts more and more scholars to study it. The paper studied of the flexural fracture performance of FRP reinforced RC beams, bringing forward how to calculate the flexural failure of FRP reinforced concrete beam, namely: bearing capacity formula about broken FRP and crushed concrete on compression zone, through comparison between calculated values and tests values, it is discovered that the numerical analysis and test result is fitting approximately, it is validated that the formula can well analyze flexural of FRP reinforced RC beams.

Experimental Research on Shear Behavior of Reinforced Concrete Beams with High-Strength Stirrup under Uniform Load

2012 ◽  
Vol 256-259 ◽  
pp. 719-723
Author(s):  
Yan Yan Li ◽  
Yan Ping Zhang ◽  
Yan Feng Chen
Keyword(s):  
Experimental Research ◽  
Crack Width ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Shear Behavior ◽  
Reinforced Concrete Beams ◽  
Uniform Load ◽  
Steel Bars ◽  
Diagonal Crack

According to tests of 8 T concrete beams with HRB500 steel bars as stirrup, the shear behavior of beams was researched under uniform load, and the influencing factors of diagonal crack width were analyzed, such as the different concrete strength, stirrup spacing and the welded wire fabric. Experimental results show that concrete beams with HRB500 steel bars as stirrup show similar behavior to the beams with conventional stirrup, and the stirrups yield can be achieved which meets the requirement of shear behavior in structure. In addition, the welded wire fabric can be used as one of the new kinds of reinforcement to control diagonal crack width.

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