scholarly journals Improvement of Stop-Hole Method on Fatigue-Cracked Steel Plates by Using High-Strength Bolts and CFRP Strips

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xu Jiang ◽  
Zhilin Lv ◽  
Xuhong Qiang ◽  
Jiandong Zhang
Keyword(s):  
Fatigue Strength ◽  
Crack Initiation ◽  
Steel Structures ◽  
High Strength ◽  
Fatigue Performance ◽  
Steel Plates ◽  
Repair Efficiency ◽  
Crack Repair ◽  
Crack Initiation Life ◽  
Effective Reinforcement

Steel bridges are extremely damaged by fatigue subjected to cycling load. Therefore, it is often necessary to put forward effective reinforcement to strengthen steel structures during the daily maintenance. In this study, two repairing methods of high-strength bolts and high-modulus CFRP strips on the basis of stop-hole repair method were introduced, respectively, to investigate fatigue improvement of cracked steel plates. First of all, numerical analysis was conducted to predict the repair efficiency and investigate the optimal parameters of each method. Variables studied were stop-hole diameter, pretightening force of bolt, and size of CFRP patch. Subsequently, a total of 12 specimens were tested to study the repairing efficiency of cracked steel plates with various strengthening methods through cyclic loading. At the same time, the failure mode and fatigue life were analyzed to present the improvement of fatigue performance. In addition, the experimental results were compared against the S-N curves of this strengthened fatigue detail. The outcomes of this study revealed that an improvement in the influence of fatigue-crack repair with the adoption of these two strengthening methods was evident. Numerical results showed that the addition of these materials could significantly diminish stress concentration factor around hole edge and improve their fatigue performance in comparison with only stop-hole method. Fatigue test results indicated that the crack initiation life of specimens repaired by stop-hole method was more than 20 times that of the unrepaired specimens. The high-strength bolt reinforced stop hole and CFRP patched stop hole can extend the crack initiation life by 9 and 8 times, respectively, in contrast to control specimens with sole stop-hole method. Finally, it was demonstrated that repairing damaged steel plates with stop-hole method alone was not enough to satisfy the fatigue strength requirements of various countries. But the fatigue strength category of damaged steel plates after further repairing with high-strength bolts and high-elastic-modulus CFRP, respectively, was higher than category A of AASHTO.

342 Effect of Contact Pressure on Crack Initiation Life in Fretting Fatigue of High Strength Steel

2000 ◽  
Vol 2000.8 (0) ◽  
pp. 293-294
Author(s):  
Kozo NAKAZAWA ◽  
Norio MARUYAMA ◽  
Takao HANAWA
Keyword(s):  
Crack Initiation ◽  
Contact Pressure ◽  
High Strength Steel ◽  
High Strength ◽  
Fretting Fatigue ◽  
Crack Initiation Life

Fatigue Analysis of Locking Parts in the Gauge-Adjustable Wheelsets System Considering the Variation of the Fatigue Strength

2008 ◽  
Vol 33-37 ◽  
pp. 217-222 ◽  
Author(s):  
Chul Su Kim ◽  
Cheon Soo Jang ◽  
Seung Ho Jang ◽  
Jung Kyu Kim
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Strength ◽  
Crack Initiation ◽  
Fatigue Analysis ◽  
Railroad Network ◽  
Fatigue Data ◽  
Curved Track ◽  
Crack Initiation Life ◽  
The Cost

To reduce the cost and time of transport due to the different track gauges(narrow, standard, broad) in the Eurasian railroad network such as TKR(Trans-Korea Railway), TCR(Trans-China Railway) and TSR(Trans-Siberia Railway), it is very necessary to develop and adapt the gauge-adjustable wheelsets system. The freight trains’ with gauge-adjustable system could operate on the different track gauges in the transcontinental railway. Therefore, to assure the safety of the newly developed gauge-adjustment wheelsets system, it is essential to evaluate integrity of locking parts in the system by using fatigue analysis. In this study, it was performed that contact stress analysis of locking parts by using FEM(Finite Element Method) in the case both the gauge changeover operation and freight trains' service in the curved track, respectively. Besides, to consider the variation of fatigue data, the crack initiation life was statistically evaluated.

Numerical Analysis of the Influence on High Humidity in a T-Joint Fillet Weld for High Strength Low Alloy Steel

2014 ◽  
Vol 651-653 ◽  
pp. 56-59
Author(s):  
Song Ping Chen ◽  
Yong Xian Li ◽  
Yan Ji Xie
Keyword(s):  
Residual Stress ◽  
Alloy Steel ◽  
Steel Structures ◽  
High Strength ◽  
Computational Procedure ◽  
Steel Plates ◽  
Transient Temperature ◽  
High Humidity ◽  
Low Alloy Steel ◽  
Port City

Welding at high humidity is frequently needed for the harbor hoisting machinery of steel structures in the coastal port city. A computational procedure is proposed for analyzing residual stress and temperature distributions induced by the T-joint welding in two types of St52-3 high strength low alloy steel plates both 6 mm in thickness. The relative humidity conditions varied from 75 to 90% at constant pressure. The finite element models are employed to evaluate the transient temperature and the residual stress during welding. According to the analysis results, the higher residual stress and the highest concentration of hydrogen are distributed in and surround the heat affected zone (HAZ), and vary with different humidity.

Fatigue Strength Evaluation of Perforated Plate at Elevated Temperature Using Stress Redistribution Locus Method

2007 ◽  
Author(s):  
Osamu Watanabe ◽  
Bopit Bubphachot ◽  
Nobuchika Kawasaki ◽  
Naoto Kasahara
Keyword(s):  
Elevated Temperature ◽  
Fatigue Strength ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Perforated Plate ◽  
Local Strain ◽  
Stress Redistribution ◽  
Experimental Results ◽  
Locus Method ◽  
Crack Initiation Life

This study reports the experimental results carried out at the elevated temperature of 550°C on fatigue strength of the perforated plate. Stress Redistribution Locus (abbreviated as SRL hereafter) Method is applied to predict fatigue life for the specimens having stress concentration. The specimens made of SUS304 stainless steel have through holes with different number and different diameter, accordingly leading to the different stress concentration condition. The inelastic local strain is estimated by the SRL method or the other previous Neuber’s rule, and compared to the experimental results on the crack initiation life at the edge of the hole using the concentrated local strain obtained by these methods. The obtained result is that the SRL method is best used with the onset of failure or crack initiation.

Retrofitting for Fatigue Cracks at Connection between the Main Girder Web and Lateral Girder Flange Using the Bolting-Stop-Hole Method with Attached Plates

2014 ◽  
Vol 891-892 ◽  
pp. 130-135
Author(s):  
Takeshi Mori ◽  
Kazuya Sasaki ◽  
Mitsuru Nakanuma
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Cracks ◽  
High Strength ◽  
Fatigue Tests ◽  
Steel Plates ◽  
Small Scale ◽  
Bolted Connections ◽  
Repair Method ◽  
Main Girder

For the purpose of clarifying the fatigue strength of a main girder web connected to a lateral girder flange which is repaired by bolting-stop-hole method with attached steel plates, fatigue tests have been performed on girder specimens. In addition, fatigue tests have been also carried out on small scale plate specimens modeling the repaired parts in order to investigate the fatigue crack origin and fatigue strength of the repaired parts. Furthermore, the effect of the repair method has been compared with those of stop-hole method and/or bolting-stop-hole method through the fatigue tests. It has been confirmed that the fatigue strength of the repaired parts is considerably high and almost equal to that of friction type of high strength bolted connections.

Tests on Cracked Steel Plates with Different Damage Levels Strengthened by CFRP Laminates

2014 ◽  
Vol 14 (06) ◽  
pp. 1450018 ◽  
Author(s):  
Qian-Qian Yu ◽  
Xiao-Ling Zhao ◽  
Riadh Al-Mahaidi ◽  
Zhi-Gang Xiao ◽  
Tao Chen ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Slow Crack Growth ◽  
Steel Structures ◽  
Steel Plates ◽  
Damage Level ◽  
Cfrp Laminates ◽  
Initial Damage ◽  
Crack Repair ◽  
Marking Technique

Strengthening steel structures using carbon fiber reinforced polymer (CFRP) materials has attracted much attention in recent years owing to their potential for fatigue crack repair and their convenience in construction. However, little is known about the efficiency of this strengthening method when applied to steel plates at different crack propagation stages. An experimental study was carried out on notched steel plates strengthened using CFRP laminates. 20 specimens were tested to evaluate the fatigue performance of the strengthened steel plates with emphasis on various degrees of initial damage, simulated by different lengths of slots, including 2%, 10%, 20%, 30% and 40% of the plate width. The effects of the retrofitted configuration and CFRP stiffness were also investigated. The "beach marking" technique and crack propagation gauges were adopted to monitor the fatigue crack propagation. The experimental results were very encouraging, demonstrating that the CFRP patches could effectively slow crack growth and extend fatigue life, regardless of the initial damage levels. More effective strengthening was found by using ultra-high modulus CFRP laminates, covering the initial cracks with CFRP and repairing at an earlier stage (i.e. smaller damage level).

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