Propagation Behavior of Main Crack in Reinforced Concrete Beams Strengthened with CFRP under Cyclic Bending Load

2013 ◽  
Vol 535-536 ◽  
pp. 205-208
Author(s):  
Zheng Wei Li ◽  
Pei Yan Huang ◽  
Hao Zhou
Keyword(s):  
Reinforced Concrete ◽  
Crack Propagation ◽  
Main Crack ◽  
Fatigue Behavior ◽  
Propagation Rate ◽  
Reinforced Concrete Beams ◽  
Rc Beam ◽  
Cyclic Bending ◽  
Propagation Behavior ◽  
Bending Load

Fatigue behavior of reinforced concrete (RC) beam can be improved by externally bonded fiber reinforced polymer (FRP). However, propagation behavior of a crack on the RC beam will have serious effect on the fatigue life of the beam strengthened with FRP. In this paper, a finite element (FE) procedure was developed to analysis the stress intensity factor (SIF) of the main crack and an experimental study was conducted to investigate the propagation rate of the main crack of the RC beam strengthened with carbon fiber laminate (CFL) under cyclic bending load. The FE analysis results show that the SIF near the main crack tip increases at the beginning and then decreases with the fatigue crack propagation. When relative crack length α is equal to 0.3, the SIF is maximum. When α approaches 0.75, the SIF approaches zero. A total of 3 RC beams strengthened with CFL were tested. The experimental results show that it is possible to divide the process of the crack propagation into three distinct phases, including crack initiation and then quickly propagation, stable propagation and then rest and unstable propagation. A semi-empirical equation based on the Paris Law was developed to predict the crack propagation rate.

Effect of Calcification on The Fatigue Behavior of Fluorinated Polyurethanes

1999 ◽  
Vol 599 ◽  
Author(s):  
R. S. Benson ◽  
H. J. Kim
Keyword(s):  
Crack Propagation ◽  
Calcium Chloride ◽  
Calcium Salt ◽  
Fatigue Behavior ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Fluorinated Polyurethane ◽  
Propagation Behavior ◽  
Tearing Energy ◽  
The Difference

AbstractThe present study compares the fatigue propagation behavior of a fluorinated and nonfluorinated polyurethane-calcium salt blends. The calcium salts used in this study are calcium chloride and hydroxyapatite (HAP). The fatigue crack propagation (FCP) behavior of the polyurethanes exhibited a dependence on the chemical composition of the polymer and calcium salt. The pure non-fluorinated PTMG2000 did no undergo crack propagation. While the fluorinated PTMG2003F exhibit a crack propagation rate of 7.8 × 10-6m/cycle at constant strain amplitude and tearing energy range. The incorporation of calcium chloride into PTMG2000 did not promote any changes in the FCP behavior; while the addition of HAP produced cracks with a growth rate of 3.33 × 10-6m/cycle. In the case of PTMG2003F, the addition of calcium chloride did not lead to formation of cracks; while HAP produced a material in which cracks propagated at a rate of 10.0 × 10-6m/cycle. The difference in the response the non-fluorinated and fluorinated polyurethane-calcium salt blends to cyclic loading can be attributed to molecular level variations such as domains disruption and changes in chain orientation at the crack tip.

scholarly journals Crack Propagation Behavior of a Ni-Based Single-Crystal Superalloy during In Situ SEM Tensile Test at 1000 °C

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1047
Author(s):  
Wenxiang Jiang ◽  
Xiaoyi Ren ◽  
Jinghao Zhao ◽  
Jianli Zhou ◽  
Jinyao Ma ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Tensile Test ◽  
Single Crystal ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Single Crystal Superalloy ◽  
Propagation Path ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

An in situ scanning electron microscope (SEM) tensile test for Ni-based single-crystal superalloy was carried out at 1000 °C. The stress displacement was obtained, and the yield strength and tensile strength of the superalloy were 699 MPa and 826 MPa, respectively. The crack propagation process, consisting of Model I crack and crystallographic shearing crack, was determined. More interestingly, the crack propagation path and rate affected by eutectics was directly observed and counted. Results show that the coalescence of the primary crack and second microcrack at the interface of a γ/γ′ matrix and eutectics would make the crack propagation rate increase from 0.3 μm/s to 0.4 μm/s. On the other hand, crack deflection decreased the rate to 0.05 μm/s. Moreover, movement of dislocations in front of the crack was also analyzed to explain the different crack propagation behavior in the superalloy.

The Bridged Crack Model for the Analysis of Brittle Matrix Fibrous Composites Under Repeated Bending Loading

2007 ◽  
Vol 74 (6) ◽  
pp. 1239-1246 ◽  
Author(s):  
Alberto Carpinteri ◽  
Simone Puzzi
Keyword(s):  
Reinforced Concrete ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Composite Beam ◽  
Crack Model ◽  
Brittle Matrix ◽  
Cyclic Bending ◽  
Mechanics Model ◽  
Bending Loading ◽  
Bridged Crack

In this paper, we present a fracture-mechanics based model, the so-called bridged crack model (Carpinteri, A., 1981, “A Fracture Mechanics Model for Reinforced Concrete Collapse,” Proc. of IABSE Colloquium on Advanced Mechanics of Reinforced Concrete, Delft, I.A.B.S.E., Zürich, pp. 17–30; Carpinteri, A., 1984, “Stability of Fracturing Process in R.C. Beams,” J. Struct. Engng. (A.S.C.E.), 110, pp. 544–558) for the analysis of brittle matrix composites with discontinuous ductile reinforcements under the condition of repeated bending loading. In particular, we address the case of composites with very high number of reinforcements (i.e., fiber-reinforced composites, rather than conventionally reinforced concrete). With this aim, we propose a new iterative procedure and compare it to the algorithm recently proposed by Carpinteri, Spagnoli, and Vantadori (2004, “A Fracture Mechanics Model for a Composite Beam with Multiple Reinforcements Under Cyclic Bending,” Int. J. Solids Struct., 41, pp. 5499–5515), showing the advantages in terms of computational efficiency. Furthermore, we analyze the combined effects of crack length, brittleness number, and fiber number on the cyclic behavior of the composite beam, showing the conditions enhancing the energy dissipation in the composite system. Eventually, we analyze crack propagation and propose, consistently with the model premises, a fracture-mechanics-based crack propagation criterion that allows one to simulate cyclic bending tests under the fixed grip condition.

Effective Method of Repairing RC Beam Using Externally Bonded Steel Plate

2014 ◽  
Vol 567 ◽  
pp. 399-404 ◽  
Author(s):  
Md Ashraful Alam ◽  
Ali Sami Abdul Jabbar ◽  
Mohd Zamin Jumaat ◽  
Kamal Nasharuddin Mustapha
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Steel Plate ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Rc Beam ◽  
External Reinforcement ◽  
Externally Bonded ◽  
Damaged Beams

Repair of reinforced concrete beam with externally bonded steel plate or fibre reinforced polymer (FRP) laminate is becoming both environmentally and economically preferable rather than replacement of deficient beam. The well known advantages of external reinforcement over other methods include; low cost, ease of maintenance and the ability to strengthen part of the structure while it is still in use. The disadvantage of this method, however, is the premature debonding of the externally bonded strips which is brittle and undesired mode of failure. It is also known that debonding of the externally bonded steel plates prevents the reinforced concrete (RC) beam from reaching its full strengthening capacity. The aim of this study was to increase the scientific understanding on the behaviour of damaged reinforced concrete beams strengthened and/or retrofitted for shear using vertical steel plate fixed with adhesive and steel connectors to eliminate or delay debonding failure. Four reinforced concrete beam specimens were prepared to investigate the effects of connectors in preventing or delaying premature debonding of shear strips to restore the capacities of fully damaged beams. Three damaged beams have been repaired and strengthened with steel plates and loaded monotonically up to the maximum load capacities in order to define load–deflection relationship. It is concluded that the repairing of severely shear-damaged RC beams with steel plates by using steel and adhesive connectors can fully restore the original shear capacities of the beams.

Fatigue Behavior of Corroded Reinforced Concrete Beams-a Review

2011 ◽  
Vol 94-96 ◽  
pp. 1523-1526
Author(s):  
Shi Bin Li ◽  
Hong Wei Tang ◽  
Xin Wang
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Fatigue Behavior ◽  
Concrete Bridges ◽  
Reinforced Concrete Beams ◽  
Rc Structures ◽  
Concrete Members ◽  
Bridge Structures ◽  
Traffic Volumes ◽  
Chloride Attack

Reinforced concrete (RC) structures are widely used in civil engineering for their merits. A good-quality concrete provides a highly alkaline environment that forms a passive film on reinforcement surface, preventing steel bars from corroding. Due to chloride attack or concrete carbonization, corrosion of embedded reinforcement in concrete members is common for RC structures. Much importance should be attached to the fatigue of corroded concrete bridges because they bear not only static loads but also alternate loads. Followed along with the aging of bridge structures, the increase of traffic volumes, the augment of vehicle loads as well as the deterioration of service environment, many corroded concrete bridges are urgently needed security appraisal and residual fatigue life forecast. Fatigue of corroded RC beams is a key problem for the existing corrosion-damaged concrete bridges. But the interrelated research was little. Based on the most new study information, the production on fatigue of corroded concrete beams was listed and analyzed, and the problems on fatigue of corroded concrete beams were indicated.

Sign in / Sign up

Export Citation Format

Share Document