Analytical assessment of the bearing capacity of RC beams with corroded steel bars beyond concrete cover cracking

Four concrete beams were cast with normal reinforcement bars. According to different the amount of mounted strengthening, grooves are opened in the concrete cover of tensile region in the concrete beams. Helical Rib Bar（HRB）is inserted in the grooves that is filled with resin. Flexural experimental results indicate that the limit bearing capacity, rigidity and crack resistance of beams strengthened with HRB are all improved obviously. With the increase in the amount of mounted strengthening, the limit bearing capacity of the strengthened beam is improved obviously. In comparison with the contrastive beam, the limit bearing capacity of the beam strengthened with one near-surface mounted HRB is increased by 20.91%, and that of the beam strengthened with two near-surface mounted HRB is increased by 54.55%，and that of the beam strengthened with three near-surface mounted HRB is increased by 90.91%.

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Influence of concrete mix proportions on lifetime flexural load-bearing capacity of RC beams under chloride corrosion of rebars

Structures ◽

10.1016/j.istruc.2021.01.009 ◽

2021 ◽

Vol 29 ◽

pp. 2017-2027

Author(s):

Fatemeh Asen ◽

Mehdi Dehestani

Keyword(s):

Bearing Capacity ◽

Rc Beams ◽

Load Bearing Capacity ◽

Load Bearing ◽

Chloride Corrosion ◽

Concrete Mix

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Modelling of Corrosion-Induced Concrete Cover Cracking Due to Chloride Attacking

Materials ◽

10.3390/ma14061440 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1440

Author(s):

Pei-Yuan Lun ◽

Xiao-Gang Zhang ◽

Ce Jiang ◽

Yi-Fei Ma ◽

Lei Fu

Keyword(s):

Service Life ◽

Corrosion Current ◽

Practical Experience ◽

Concrete Cover ◽

Premature Failure ◽

Rc Structures ◽

Structural Capacity ◽

Cover Cracking ◽

Deterioration Process ◽

Cracking Process

The premature failure of reinforced concrete (RC) structures is significantly affected by chloride-induced corrosion of reinforcing steel. Although researchers have achieved many outstanding results in the structural capacity of RC structures in the past few decades, the topic of service life has gradually attracted researchers’ attention. In this work, based on the stress intensity, two models are developed to predict the threshold expansive pressure, corrosion rate and cover cracking time of the corrosion-induced cracking process for RC structures. Specifically, in the proposed models, both the influence of initial defects and modified corrosion current density are taken into account. The results given by these models are in a good agreement with practical experience and laboratory studies, and the influence of each parameter on cover cracking is analyzed. In addition, considering the uncertainty existing in the deterioration process of RC structures, a methodology based on the third-moment method in regard to the stochastic process is proposed, which is able to evaluate the cracking risk of RC structures quantitatively and predict their service life. This method provides a good means to solve relevant problems and can prolong the service life of concrete infrastructures subjected to corrosion by applying timely inspection and repairs.

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Inclusion of CFRP-Epoxy Composite for End Anchorage in NSM-Epoxy Strengthened Beams

Advances in Materials Science and Engineering ◽

10.1155/2015/812797 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Md. Akter Hosen ◽

Mohd Zamin Jumaat ◽

A. B. M. Saiful Islam

Keyword(s):

Reinforced Concrete ◽

Failure Modes ◽

Concrete Cover ◽

Structural Members ◽

Premature Failure ◽

Near Surface ◽

Steel Bars ◽

Near Surface Mounted ◽

Separation Failure ◽

Concrete Cover Separation

Nowadays, the use of near surface mounted (NSM) technique strengthening reinforced concrete (RC) structural members is going very popular. The failure modes of NSM strengthened reinforced concrete (RC) beams have been shown to be largely due to premature failure such as concrete cover separation. In this study, CFRP U-wrap end anchorage with CFRP fabrics was used to eliminate the concrete cover separation failure. A total of eight RC rectangular beam specimens of 125 mm width, 250 mm depth, and 2300 mm length were tested. One specimen was kept unstrengthened as a reference; three specimens were strengthened with NSM steel bars and the remaining four specimens were strengthened with NSM steel bars together with the U-wrap end anchorage. The experimental results showed that wrapped strengthened beams had higher flexural strength and superior ductility performance. The results also show that these beams had less deflection, strain, crack width, and spacing.

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Comparison of flexural capacity of different hollow slab beams with/without pavement layer reinforced by steel plates

Multidiscipline Modeling in Materials and Structures ◽

10.1108/mmms-07-2021-0134 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Long Liu ◽

Lifeng Wang ◽

Ziwang Xiao

Keyword(s):

Finite Element ◽

Bearing Capacity ◽

Steel Plate ◽

Plate Thickness ◽

Experimental Results ◽

Nonlinear Material ◽

Finite Element Models ◽

Rc Beams ◽

Flexural Capacity ◽

Content Type

PurposeReinforcement of reinforced concrete (RC) beams in-service have always been an important research field, anchoring steel plate in the bottom of the beams is a kind of common reinforcement methods. In actual engineering, the contribution of pavement layer to the bearing capacity of RC beams is often ignored, which underestimates the bearing capacity and stiffness of RC beams to a certain extent. The purpose of this paper is to study the effect of pavement layer on the RC beams before and after reinforcement.Design/methodology/approachFirst, static load experiments are carried out on three in-service RC hollow slab beams, meanwhile, nonlinear finite element models are built to study the bearing capacity of them. The nonlinear material and shear slip effect of studs are considered in the models. Second, the finite element models are verified, and the numerical simulation results are in good agreement with the experimental results. Last, the finite element models are adopted to carry out the research on the influence of different steel plate thicknesses on the flexural bearing capacity and ductility.FindingsThe experimental results showed that pavement layers increase the flexural capacity of hollow slab beams by 16.7%, and contribute to increasing stiffness. Ductility ratio of SPRCB3 and PRCB2 was 30% and 24% lower than that of RCB1, respectively. The results showed that when the steel plate thickness was 1 mm–6 mm, the bearing capacity of the hollow slab beam increased gradually from 2158.0 kN.m to 2656.6 kN.m. As the steel plate thickness continuously increased to 8 mm, the ultimate bearing capacity increased to 2681.0 kN.m. The increased thickness did not cause difference to the bearing capacity, because of concrete crushing at the upper edge.Originality/valueIn this paper, based on the experimental study, the bearing capacity of hollow beam strengthened by steel plate with different thickness is extrapolated by finite element simulation, and its influence on ductility is discussed. This method not only guarantees the accuracy of the bearing capacity evaluation, but also does not require a large number of samples, and has certain economy. The research results provide a basis for the reinforcement design of similar bridges.

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Analysis of Crack Patterns of 500MPa Reinforced Concrete Beams

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.790.120 ◽

2013 ◽

Vol 790 ◽

pp. 120-124

Author(s):

Zhi Hua Li ◽

Xiao Zu Su

Keyword(s):

Static Loading ◽

Crack Width ◽

Concrete Beams ◽

Concrete Cover ◽

Reinforced Concrete Beams ◽

Crack Control ◽

Crack Patterns ◽

Beam Depth ◽

Steel Bars ◽

Constant Moment

Fourting concrete beams reinforced with 500MPa longitudinal steel bars, of which 6 with skin reinforcement and 8 without skin reinforcement, were tested under two-point symmetrical concentrated static loading to investigate their crack patterns. Crack distributions in constant moment region of beams are compared. The propagation of side cracks along the beam depth is obtained. The results of this study indicate that the concrete cover of longitudinal tensile steel bars and the spacing of skin reinforcement has significant effect on crack distributions; substantial crack control in beams can be achieved if the spacing of skin reinforcement is limited to certain critical values. The curve of d-w(d is the distance between observation points of side cracks and tension face of beams, w refers to crack width at observation points) is approximately characterized by a zig-zag shape and concave-left near longitudinal tensile steel bars.

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Fracture toughness of RC beams on the shear, strengthening by FRCM system

MATEC Web of Conferences ◽

10.1051/matecconf/201818302009 ◽

2018 ◽

Vol 183 ◽

pp. 02009 ◽

Cited By ~ 9

Author(s):

Zinoviy Blikharskyy ◽

Pavlo Vegera ◽

Rostyslav Vashkevych ◽

Taras Shnal

Keyword(s):

Fracture Toughness ◽

Bearing Capacity ◽

Shear Failure ◽

Control Sample ◽

Variable Parameter ◽

Rc Beams ◽

Maximum Width ◽

Shear Span ◽

Initial Load ◽

Inclined Cracks

This research paper present the experimental study of reinforce concrete beams strengthened by FRCM system in the shear area. All samples are without transverse reinforcement at the shear distance. First beams tested as control sample, with shear distance a/d=2. Another three beams tested with strengthening by FRCM system. Variable parameter is the level of initial load, before strengthening. The initial load values were 0, 0.3, 0.5 from carrying capacity of control samples. All RC beams were designed to fail in shear, even strengthened samples. In the result of this research we determined that fracture toughness of RC beams increases with a decrease of span to the effective depth ratio. Results are comparable with the increasing of bearing capacity. The first inclined crack opend in mid-height cross section at the load 50 kN at an angle equal to 450 and it does not depend on the shear span. The maximum width of inclined cracks decrease with decreasing of shear span. The maximum width of inclined cracks decrease with decreasing of the shear span. The maximum values of width of inclined cracks are fixed at the value of 0.55 - 0.85 mm. Using the limit crack opening width as criteria of exhaustion of serviceability (SLS) we saw that about 16 - 29% of bearing capacity still remains before the danger of shear failure of the beam.

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