Flexural Fracture and Fatigue Behavior of RC Beams Strengthened with CFRP Laminates under Constant Amplitude Loading

Externally bonded carbon fiber reinforced polymer (CFRP) materials are well suited to the rehabilitation and reinforcement of civil engineering structures due to their high specific strength, specific stiffness and corrosion resistance. To probe the fatigue behavior of CFRP strengthened concrete structures, three point bending experiments of reinforced concrete (RC) beams strengthened with carbon fibre laminate (CFL) under constant amplitude loading were performed. The histories of midspan flexibility and bending stiffness of strengthened beams were recorded automatically. And the linear curve between fatigue strength and the logarithm of fatigue life was obtained. The failure modes go through concrete cracking, CFL debonding from concrete and steel bars yielding and fracture with increasing cycles of fatigue loading. Bonded CFL increases the ductility of strengthened RC beam and results in dense distribution of cracks compared with normal RC beam, and it’s bending stiffness at damage state as well. The fatigue damage evolvement shows three stages of nucleation, steady expansion and failure. Then the failure mechanism was studied and a cumulative damage model was proposed to describe the fatigue damage and fracture process of CFL strengthened RC beams under constant amplitude loading.

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Fatigue Performance of Partially Prestressed RC Beams with HRBF500 Bars

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.174-177.1463 ◽

2012 ◽

Vol 174-177 ◽

pp. 1463-1470

Author(s):

Ke Li ◽

Xin Ling Wang ◽

Shuang Yin Cao

Keyword(s):

Prestressed Concrete ◽

Concrete Beams ◽

Fatigue Behavior ◽

Fatigue Loading ◽

Fatigue Tests ◽

Fatigue Properties ◽

Repeated Loading ◽

Rc Beams ◽

Constant Amplitude ◽

Hot Rolled

500 MPa level hot-rolled ribbed bars of fine grains (HRBF500) is a successfully developed new-type steel in Chain. The fatigue behavior of partially prestressed reinforced concrete (RC) beams with HRBF500 bars was investigated in fatigue tests of pre-tensioned T-beams. The beams are simply supported with the same overall dimensions, and the main parameter in the study is prestress degree and longitudinal steel ratio. Four beams were constructed and tested under constant-amplitude fatigue loading. All beams are initially cracked before the application of repeated loading. The stress evolution of HRBF500 bars and prestressed strands, the information about crack growth and the deflection developments of test beams were presented. The main factors that affect the fatigue properties of prestressed concrete test beams were fully discussed. Test results indicate that, the prestressed concrete beams reinforced with appropriate amount of HRBF500 bars and reasonable prestressing conﬁgurations can survive 2.5 millions cycles of constant-amplitude fatigue loading using an upper-bound fatigue load producing tensile stress of less than 150 MPa in HRBF500 bars. The results provide important guidance for the fatigue design of prestressed concrete beams with HRBF500 bars.

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Flexural Performance of RC Beams Strengthened with Externally-Side Bonded Reinforcement (E-SBR) Technique Using CFRP Composites

Materials ◽

10.3390/ma14112809 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2809

Author(s):

Md. Akter Hosen ◽

Fadi Althoey ◽

Mohd Zamin Jumaat ◽

U. Johnson Alengaram ◽

N. H. Ramli Sulong

Keyword(s):

Absorption Capacity ◽

Experimental Program ◽

Rc Beams ◽

Rc Structures ◽

Functional Changes ◽

Flexural Strengthening ◽

Cfrp Laminates ◽

Flexural Performance ◽

Design Loads ◽

Predicted Values

Reinforced concrete (RC) structures necessitate strengthening for various reasons. These include ageing, deterioration of materials due to environmental effects, trivial initial design and construction, deficiency of maintenance, the advancement of design loads, and functional changes. RC structures strengthening with the carbon fiber reinforced polymer (CFRP) has been used extensively during the last few decades due to their advantages over steel reinforcement. This paper introduces an experimental approach for flexural strengthening of RC beams with Externally-Side Bonded Reinforcement (E-SBR) using CFRP fabrics. The experimental program comprises eight full-scale RC beams tested under a four-point flexural test up to failure. The parameters investigated include the main tensile steel reinforcing ratio and the width of CFRP fabrics. The experimental outcomes show that an increase in the tensile reinforcement ratio and width of the CFRP laminates enhanced the first cracking and ultimate load-bearing capacities of the strengthened beams up to 141 and 174%, respectively, compared to the control beam. The strengthened RC beams exhibited superior energy absorption capacity, stiffness, and ductile response. The comparison of the experimental and predicted values shows that these two are in good agreement.

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Fatigue behavior and prediction model of self-compacting concrete under constant amplitude load and incremental amplitude load

International Journal of Fatigue ◽

10.1016/j.ijfatigue.2020.106107 ◽

2021 ◽

Vol 145 ◽

pp. 106107

Author(s):

Lu Feng ◽

Xudong Chen ◽

Jinhua Zhang ◽

Jiayi Yuan ◽

Wen Dong

Keyword(s):

Prediction Model ◽

Fatigue Behavior ◽

Constant Amplitude ◽

Self Compacting Concrete

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Compressive fatigue behavior of low velocity impacted and quasi-static indented CFRP laminates

Composite Structures ◽

10.1016/j.compstruct.2015.08.046 ◽

2015 ◽

Vol 133 ◽

pp. 1009-1015 ◽

Cited By ~ 8

Author(s):

Jianyu Zhang ◽

Libin Zhao ◽

Ming Li ◽

Yuli Chen

Keyword(s):

Fatigue Behavior ◽

Low Velocity ◽

Cfrp Laminates

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Constant-amplitude fatigue behavior of M24 high-strength bolt of end-plate flange connection

Structures ◽

10.1016/j.istruc.2021.08.108 ◽

2021 ◽

Vol 34 ◽

pp. 2041-2053

Author(s):

Jinfeng Jiao ◽

Zhanxiang Liu ◽

Qi Guo ◽

Yong Liu ◽

Honggang Lei

Keyword(s):

Fatigue Behavior ◽

High Strength ◽

Constant Amplitude ◽

Flange Connection ◽

End Plate ◽

High Strength Bolt

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Experimental Study of Aged and Seriously Damaged RC Beams Strengthened Using CFRP Composites

Advances in Materials Science and Engineering ◽

10.1155/2018/6260724 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 5

Author(s):

Ning Zhuang ◽

Honghan Dong ◽

Da Chen ◽

Yeming Ma

Keyword(s):

Mechanical Properties ◽

Fiber Reinforced Polymer ◽

Carbon Fiber Reinforced Polymer ◽

Rc Beams ◽

Yield Load ◽

Cfrp Laminates ◽

Load Growth ◽

Reinforced Polymer ◽

Bonding Length ◽

Damaged Beams

This paper presents results from experiments on aged and seriously damaged reinforced concrete (RC) beams strengthened with different arrangements of external carbon fiber-reinforced polymer (CFRP) laminates and end anchorages. Seven RC beams from an old bridge, measuring 250 × 200 × 2300 mm, were tested. All specimens were loaded to yield load to evaluate initial mechanical properties. Then, these seriously damaged specimens were repaired using different CFRP-reinforcing schemes and reloaded to failure. The yield load growth due to CFRP reinforcement ranged from 5% to 36%. Different parameters including CFRP dimension and position, bonding length, and end anchorage were investigated and facilitated conclusions on beam ductility, load-midspan deflection response, and failure mode. This research contributes to knowledge about the CFRP repair of aged and seriously damaged beams to ensure better performance in overloaded conditions.

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