scholarly journals Fatigue Stress-Life Model of RC Beams Based on an Accelerated Fatigue Method

2019 ◽  
Vol 4 (2) ◽  
pp. 16
Author(s):  
Eljufout ◽  
Toutanji ◽  
Al-Qaralleh
Keyword(s):  
Cyclic Loading ◽  
Fatigue Testing ◽  
Three Dimensional ◽  
Rc Beam ◽  
Rc Beams ◽  
Testing Methods ◽  
Load Range ◽  
Fatigue Stress ◽  
Life Model ◽  
Prediction Band

Several standard fatigue testing methods are used to determine the fatigue stress-life prediction model (S-N curve) and the endurance limit of Reinforced Concrete (RC) beams, including the application of constant cyclic tension-tension loads at different stress or strain ranges. The standard fatigue testing methods are time-consuming and expensive to perform, as a large number of specimens is needed to obtain valid results. The purpose of this paper is to examine a fatigue stress-life predication model of RC beams that are developed with an accelerated fatigue approach. This approach is based on the hypothesis of linear accumulative damage of the Palmgren–Miner rule, whereby the applied cyclic load range is linearly increased with respect to the number of cycles until the specimen fails. A three-dimensional RC beam was modeled and validated using ANSYS software. Numerical simulations were performed for the RC beam under linearly increased cyclic loading with different initial loading conditions. A fatigue stress-life model was developed that was based on the analyzed data of three specimens. The accelerated fatigue approach has a higher rate of damage accumulations than the standard testing approach. All of the analyzed specimens failed due to an unstable cracking of concrete. The developed fatigue stress-life model fits the upper 95% prediction band of RC beams that were tested under constant amplitude cyclic loading.

Fatigue performance of modular expansion joints for bridges

2006 ◽  
Vol 33 (8) ◽  
pp. 921-932 ◽  
Author(s):  
Omar Chaallal ◽  
Guillaume Sieprawski ◽  
Lotfi Guizani
Keyword(s):  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Fatigue Performance ◽  
Horizontal Load ◽  
Stress Range ◽  
Expansion Joint ◽  
Load Range ◽  
Fatigue Stress ◽  
Number Of Cycles ◽  
Welded Connection

This paper presents results of an experimental investigation on the fatigue performance of the welded multiple support bar modular bridge expansion joint (MBEJ) used for the recent Jacques Cartier Bridge rehabilitation in Montreal. Three identical subassemblies of the modular joint system were tested in fatigue. Both vertical and horizontal load ranges were applied to the test specimen simultaneously in the following proportions: (i) vertical load range = ΔPv and (ii) horizontal load range = 0.2ΔPv. Different loading ranges were applied to each specimen giving a sufficient number of points to define the experimental fatigue stress range versus the number of cycles (S–N) curve. The number of cycles varied between 567 900 and 3 600 000, while the calculated stress range within the welded connection details varied between 81.4 and 166.7 MPa. Static calibration tests were performed prior to the fatigue testing of each specimen. These calibration tests confirmed the validity of the structural three-dimensional analytical models and also established the repeatability of the experimental data, in conformity with the requirements of the NCHRP-402 report. Fatigue cracks of the same type as those reported by the NCHRP-402 report were observed within the welded connection detail. No fatigue cracks were observed elsewhere. The experimental fatigue curve of the welded connection showed that the fatigue resistance of the welded MBEJ is compatible with category C and C' details, as defined by the AASHTO LRFD 1998 bridge design code. This paper is very useful, as it demonstrates the applicability of the complex requirements of the NCHRP-402 report. These requirements are increasingly gaining wide acceptance among bridge engineers and bridge owners.Key words: modular expansion joint, bridge, deck, test, fatigue, stress range, cycles.

Behaviour of RC beam repaired using alkali activated slag-based agent under static and cyclic loading

Structures ◽  
2021 ◽  
Vol 31 ◽  
pp. 761-768
Author(s):  
Sulaem Musaddiq Laskar ◽  
Ruhul Amin Mozumder ◽  
Aminul Islam Laskar
Keyword(s):  
Cyclic Loading ◽  
Rc Beam ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Static And Cyclic Loading ◽  
Alkali Activated

Electrical Resistance and Acoustic Emission During Fatigue Testing of Pristine and High Velocity Impact SiC/SiC Composites at Room and Elevated Temperature

2016 ◽  
Author(s):  
Zipeng Han ◽  
Gregory N. Morscher ◽  
Emmanuel Maillet ◽  
Manigandan Kannan ◽  
Sung R. Choi ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Acoustic Emission ◽  
Cyclic Loading ◽  
Electrical Resistance ◽  
Fatigue Testing ◽  
Early Stage ◽  
Loading Conditions ◽  
Initial Attempt ◽  
Matrix Cracks ◽  
Sic Composites

Electrical resistance (ER) is a relatively new approach for real-time monitoring and evaluating damage in SiC/SiC composites for a variety of loading conditions. In this study, ER of woven silicon carbide fiber-reinforced silicon carbide composite systems in their pristine and impacted state were measured under cyclic loading conditions at room and high temperature (1200C). In addition, modal acoustic emission (AE) was also monitored, which can reveal the occasion of matrix cracks and fiber. ER measurement and AE technique are shown in this study to be useful methods to monitor damage and indicate the failure under cyclic loading. Based on the slope of the ER evolution, an initial attempt has been made to develop a method allowing a critical damage phase to be identified. While the physical meaning of the critical point is not yet clear, it has the potential to allow the failure to be indicated at its early stage.

Biomechanical characteristics of C1–2 cable fixations

1996 ◽  
Vol 85 (2) ◽  
pp. 316-322 ◽  
Author(s):  
Curtis A. Dickman ◽  
Neil R. Crawford ◽  
Christopher G. Paramore
Keyword(s):  
Cyclic Loading ◽  
Translational Motion ◽  
Biomechanical Testing ◽  
Three Dimensional ◽  
Constrained Motion ◽  
Content Type ◽  
Physiological Range ◽  
Fixation Techniques ◽  
Cable Fixation ◽  
Fine Print

✓ The biomechanical characteristics of four different methods of C1–2 cable fixation were studied to assess the effectiveness of each technique in restoring atlantoaxial stability. Biomechanical testing was performed on the upper cervical spines of four human cadaveric specimens. Physiological range loading was applied to the atlantoaxial specimens and three-dimensional motion was analyzed with stereophotogrammetry. The load–deformation relationships and kinematics were measured, including the stiffness, the angular ranges of motion, the linear ranges of motion, and the axes of rotation. Specimens were nondestructively tested in the intact state, after surgical destabilization, and after each of four different methods of cable fixation. Cable fixation techniques included the interspinous technique, the Brooks technique, and two variants of the Gallie technique. All specimens were tested immediately after fixation and again after the specimen was fatigued with 6000 cycles of physiological range torsional loading. All four cable fixation methods were moderately flexible immediately; the different cable fixations allowed between 5° and 40° of rotational motion and between 0.6 and 7 mm of translational motion to occur at C1–2. The Brooks and interspinous methods controlled C1–2 motion significantly better than both of the Gallie techniques. The motion allowed by one of the Gallie techniques did not differ significantly from the motion of the unfixed destabilized specimens. All cable fixation techniques loosened after cyclic loading and demonstrated significant increases in C1–2 rotational and translational motions. The bone grafts shifted during cyclic loading, which reduced the effectiveness of the fixation. The locations of the axes of rotation, which were unconstrained and mobile in the destabilized specimens, became altered with cable fixation. The C1–2 cables constrained motion by shifting the axes of rotation so that C-1 rotated around the fixed cable and graft site. After the specimen was fatigued, the axes of rotation became more widely dispersed but were usually still localized near the cable and graft site. Adequate healing requires satisfactory control of C1–2 motion. Therefore, some adjunctive fixation is advocated to supplement the control of motion after C1–2 cable fixation (that is, a cervical collar, a halo brace, or rigid internal fixation with transarticular screws).

Flexural Fatigue Performance of RC Beams Strengthened with Hybrid Fiber Sheets

2012 ◽  
Vol 166-169 ◽  
pp. 1657-1662
Author(s):  
Xu Jun Chen ◽  
Xiao E Zhu ◽  
Zhong Yang ◽  
Mu Xiang Dai
Keyword(s):  
Fatigue Life ◽  
Basalt Fiber ◽  
Reinforced Concrete Beams ◽  
Fatigue Performance ◽  
Rc Beam ◽  
Rc Beams ◽  
Hybrid Fiber ◽  
Cycle Number ◽  
Flexural Fatigue ◽  
Variation Characteristics

Based on the fatigue test for flexural performance of five reinforced concrete beams, the variation characteristics of the crack development, concrete strain, steel strain, fiber strain with the cycle number of the fatigue load were analyzed, and the effect of hybrid fiber sheets and basalt fiber reinforced polymer(BFRP)sheets on flexural fatigue performance of the strengthened beam was studied. The results show that the accumulated damage of RC beams strengthened with hybrid fiber sheets was slowed down significantly, the anti-crack property was much improved, and the fatigue life was greatly prolonged. Compared with the ordinary RC beam and the RC beam strengthened with double BFRP sheets, the fatigue life of RC beams strengthened with hybrid CFRP/BFRP(C/BFRP) sheets and hybrid CFRP/GFRP(C/GFRP) sheets was increased by 291.26%, 298.63% and 10.73%, 13.53%.

Nonlinear Analysis of RC Beam Subject to Cyclic Loading

2001 ◽  
Vol 127 (12) ◽  
pp. 1436-1444 ◽  
Author(s):  
Hyo-Gyoung Kwak ◽  
Sun-Pil Kim
Keyword(s):  
Cyclic Loading ◽  
Nonlinear Analysis ◽  
Rc Beam

Sensitivity Study of Probit and Two-Point Fatigue Testing Methods

2006 ◽  
Author(s):  
Jiangtao Song ◽  
Paul N. Crepeau ◽  
Randy J. Gu ◽  
Zissimos P. Mourelatos
Keyword(s):  
Fatigue Testing ◽  
Sensitivity Study ◽  
Testing Methods

Fatigue Testing of Large-Scale Models of Submarine Structural Details

1965 ◽  
Vol 2 (03) ◽  
pp. 299-307
Author(s):  
Frank W. Dunham
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Pressure Variation ◽  
Test Tank ◽  
Initiation And Propagation ◽  
Scale Models ◽  
Structural Details

The conversion of a 30-ft-dia test tank to a facility for subjecting large-scale models of submarine structural details to cyclic loading is described. By means of automatically controlled valves, models were subjected to a pressure variation simulating a submarine diving to its test depth and returning to the surface. The cyclic rate was slightly less than one per minute. The system was so designed that the test tank itself was not subjected to the pressure variations. Details of a series of models designed to simulate particular structural details of interest in recent submarine construction are described. Results of the tests to date are summarized, and several observations relative to the initiation and propagation of fatigue cracks in submarine structural details are presented.

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