Design of Crack Removal Profiles Based on Shape Development of Surface Defects

2003 ◽  
Author(s):  
J. Efrai´n Rodri´guez-Sa´nchez ◽  
William D. Dover ◽  
Feargal P. Brennan
Keyword(s):  
Surface Defects ◽  
Fatigue Cracks ◽  
Plate Thickness ◽  
Steel Structures ◽  
Tubular Joints ◽  
Notch Geometry ◽  
Repair Procedure ◽  
Profile Design ◽  
Bending Loading ◽  
Surface Plate

A crack removal has the purpose to stop crack propagation and prevent future crack reinitiation, thus fatigue life of the component is extended. A profile design for the removal of fatigue cracks that grow under bending loading is presented. The design is based on the preferred shape development of surface defects under bending loading. Preferred shape development of surface defects was experimentally identified and validated with observations previously reported by other authors. The design of a crack removal profile consists on determining a notch geometry and its dimensions to cut out a crack. The crack removal profile presented here induces crack reinitiation, if it would occur, on the surface plate at the notch ends rather than in the bottom of the notch, so original plate thickness is reinstalled for propagation and inspection is easier. This repair procedure is recommended for the removal of fatigue cracks in tubular joints of offshore jackets steel structures.

scholarly journals Infiuence of Notch Geometry and Plate Thickness on Fracture Stress and Critical C.O.D.

1971 ◽  
Vol 40 (7) ◽  
pp. 658-665
Author(s):  
Kenichi Minami ◽  
Kenzo Miya ◽  
Mitsuo Sato
Keyword(s):  
Fracture Stress ◽  
Plate Thickness ◽  
Notch Geometry

scholarly journals DESIGN OF PERKUWEN BRIDGE PART WAY LONG IKIS-LAMBAKAN PASER TANA PASER REGENCY PROVINCE EAST KALIMANTAN

CERUCUK ◽  
2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Humaira Afrila ◽  
Markawie Markawie
Keyword(s):  
Design Method ◽  
Plate Thickness ◽  
Steel Structures ◽  
Structure Design ◽  
Steel Pipe ◽  
Pipe Pile ◽  
East Kalimantan ◽  
Composite Bridges ◽  
Composite Bridge ◽  
Steel Pipe Pile

Long Kali is a sub-district of Paser Tana Paser Regency Prov. East Kalimantan. In this sub-district have two village separate by a river, that is Perkuwen river, there is bridge has a broke. Whereas the village very needed a bridge because it is used as a transportation infrastructure for peoples and also passed by vehicles transporting oil palm yields . Therefore, the design of composite bridges made with spans 25 m and 7 m wide bridge.In this plan the analysis of Standard methods of loading refers to the bridge imposition For RSNI T-02-2005 about composite bridge structure design method, refers to RSNI T-03-2005 about Steel Structural Design For Bridge, SNI 03-1729-2002 about Steel Structures Planning Procedures and SNI 03-2847-2002 about Concrete Structures Calculation for Building.The result is used the main girder profile SH 950 x 400 x 16 x 32 and diaphragm WF 400 x 200 x 8 x 13. Vehicle floor plate thickness 20 cm using quality concrete  30 MPa and quality reinforcing steel reinforcement  360 MPa with subject dividers reinforcement D22- 100 and D12-100 mm. In using concrete pavement  30 MPa D22-100 mm staple reinforcement and shear reinforcement rebars quality D12-100 mm  360 MPa. Concrete abutment in the form  25 MPa at 2 m height and length of 8,5 m. Steel pipe pile foundations quality  25 MPa are 16 pieces with a length of 10 meters and a diameter of 0.4 m.Keyword: Bridge, composite, steel pipe pile.

Structural, technological and Aesthetical Considerations for the Detailing of Steel Tubular Joints

2018 ◽  
Author(s):  
Vasil Georgiev Georgiev ◽  
Dimitar Dakov ◽  
Yavor Mihov
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Civil Engineering ◽  
Fatigue Cracks ◽  
High Stress ◽  
Traffic Sign ◽  
Tubular Joints ◽  
Joint Repair ◽  
Tubular Joint ◽  
Supporting Structures

<p>For the majority of steel outdoor facilities (towers, masts, billboards and traffic-sign supporting structures) wind loading is the governing factor for determining their resistance and stiffness. In many cases fatigue-related issues appear, with cracking and failure in the welded connections of tubular joints or in the parent metal adjacent to the welds.</p><p>Structural detailing of the joints in steel tubular structures subjected to repeated cyclic loading is of great importance for their fatigue strength. Sharp changes in the shape, sharp turns in the welds and notches give rise to high stress concentration. The combined effect of discontinuities and stress concentration is the main cause for the formation and propagation of fatigue cracks. When detailing the erection joints it is also necessary to observe technological requirements related to efficiency of fabrication. For the civil engineering works exposed to public it is indispensable to include additional requirements for the aesthetic appearance of their visible structural parts. The design experience shows that applying aesthetic considerations to steel tubular joint detailing may contribute to satisfying the increased fatigue strength requirements.</p><p>The paper presents a study on the wind action on a specific kind of civil engineering works (traffic- sign supporting structures) and the approach used for its determination. The leading structural, technological and aesthetic criteria to be implemented in the detailing of tubular erection joints are formulated. An example of tubular joint destroyed due to propagation of fatigue crack is given and possible options for the joint repair are proposed. Numerical modeling and analyses of the original and repaired joints have been carried out in order to make conclusions for the advantages and shortcomings of the joint repair options.</p>

Deformation Measurements on Full-Scale Fracture Tests of Pre-Cracked Tubular Joints

2003 ◽  
Author(s):  
Bijan Talei-Faz ◽  
Feargal P. Brennan ◽  
Stuart Robson
Keyword(s):  
Large Scale ◽  
Fatigue Testing ◽  
Three Dimensional ◽  
Steel Structures ◽  
High Strength ◽  
Static Strength ◽  
Full Scale ◽  
Structural Testing ◽  
Tubular Joints ◽  
Large Steel

A series of six static strength destructive tests were performed on full-scale pre-cracked tubular welded T-joints manufactured from a high strength weldable steel used in the construction of offshore Jack-Up platforms. All specimens had at least one through-thickness fatigue crack at the weld toe, from a previous fatigue-testing programme. The tests were aimed at analysing the residual static strength of the cracked members. As destructive tests are costly to perform, every effort was made to maximise the data collected. This included the use of a novel photogrammetric technique to provide three-dimensional measurement in real time of the deformation in the vicinity of the brace-chord intersection. The technique has been used for large-scale structural testing in a number of civil and aerospace applications, but to the author’s knowledge this is the first time that it has been employed for the full-scale mechanical testing of large steel structures. This paper describes the details of the photogrammetric technique applied to the large steel specimens which were loaded to failure, resulting in the total separation of the intersecting members. It is hoped that the technique can be used to generate information which can be used in conjunction with finite element or other numerical analyses to increase the accuracy and reliability of modelling cracked tubular joints.

Application of Plastic Optical Fiber Fatigue Sensor in Real-Time Monitoring of Fatigue Cracks in Steel Structures

2020 ◽  
Vol 15 (7) ◽  
pp. 864-869
Author(s):  
Ying Liu
Keyword(s):  
Signal Processing ◽  
Optical Fiber ◽  
Real Time ◽  
Fatigue Cracks ◽  
Steel Structures ◽  
Luminous Flux ◽  
Plastic Optical Fiber ◽  
Signal Processing Algorithm ◽  
New Type ◽  
Fatigue Sensor

Plastic optical fiber (POF) is a new type of sensing material. Compared with traditional quartz optical fiber, it has the advantages of good tenacity, low cost, easy processing, and high sensitivity. A new type of POF-Fatigue sensor (nPOF-Fs) is designed by using POF, which is based on the changes the luminous flux. The change in the relative displacement of the two ends of the fiber is obtained through the change in the luminous flux in the POF, which is later converted into an electrical signal by the photoelectric conversion device. By collecting and analyzing the signals, accurate measurement of the dynamic response of the workpiece is achieved. Combined with the signal processing algorithm that can detect and monitor the crack expansion of steel structures under cyclic loading based on the RMS envelope and Hilbert transform filters, the fatigue crack can be monitored in real-time. The results obtained by nPOF-Fs are fundamentally coincide with the results acquired by the COD sensor. In view of the higher cost of monitoring with the COD sensor, the use of a POF sensor combined with a signal processing algorithm in monitoring the occurrence and expansion of fatigue cracks has great potential in the field of structural monitoring.

Efficient detection method of fatigue cracks in steel structures

2018 ◽  
Vol 2018.17 (0) ◽  
pp. 206
Author(s):  
Yushi YAMANE ◽  
Noboru SASAKI ◽  
Hideki ENDO ◽  
Tsuyoshi ASHIDA ◽  
Tsutomu MORIMOTO ◽  
...  
Keyword(s):  
Detection Method ◽  
Fatigue Cracks ◽  
Steel Structures ◽  
Efficient Detection

Applications of Probabilistic Fracture Mechanics to Offshore Structures

1988 ◽  
Vol 41 (2) ◽  
pp. 61-84 ◽  
Author(s):  
Finn Kirkemo
Keyword(s):  
Fracture Mechanics ◽  
Model Updating ◽  
Fatigue Cracks ◽  
Limit State ◽  
Steel Structures ◽  
Local Stress ◽  
Offshore Structures ◽  
And Performance ◽  
Fatigue Limit State ◽  
Life Predictions

For offshore structures the fatigue limit state is governing the structural dimensions of several members and joint connections. Safety against fatigue failure is achieved through a combination of design requirements and performance of in-service inspections with repair of detected fatigue cracks. A review of uncertainties involved in fatigue life predictions by fracture mechanics is presented with particular reference to steel structures. Sources of uncertainties considered are: environmental conditions, hydrodynamic loading, global structural analysis, local stress calculation at fatigue sensitive points, and fatigue crack growth modeling by fracture mechanics. A probabilistic model using the fracture mechanics in probabilistic form is presented. This model accounts for uncertainties in loading, initial and critical defect sizes, material parameters, and in the uncertainty related to computation of the stress intensity factor. Failure probabilities are computed by first-order reliability methods and sensitivity factors are determined. Model updating based on in-service inspection results is formulated. Uncertainties with respect to detecting a crack and to correctly sizing a crack are included. Experience on application of the analysis method is presented.

02.08: The influence of plate thickness on the welding residual stresses from submerged arc welding in offshore steel structures

ce/papers ◽  
2017 ◽  
Vol 1 (2-3) ◽  
pp. 499-504 ◽  
Author(s):  
Michael Joachim Andreassen ◽  
Zhenzhen Yu ◽  
Stephen Liu ◽  
Jens Henrik Nielsen
Keyword(s):  
Residual Stresses ◽  
Arc Welding ◽  
Plate Thickness ◽  
Steel Structures ◽  
Submerged Arc Welding ◽  
Submerged Arc

Influence of Predetermined Surface Defect to the Bendability of Ultra-High-Strength Steel

2012 ◽  
Vol 504-506 ◽  
pp. 901-906 ◽  
Author(s):  
Antti Määttä ◽  
Antti Järvenpää ◽  
Matias Jaskari ◽  
Kari Mäntyjärvi ◽  
Jussi A. Karjalainen
Keyword(s):  
Surface Defects ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Crack Size ◽  
Critical Crack ◽  
Bending Radius ◽  
Ultra High Strength Steels ◽  
Materials Used ◽  
Critical Crack Size

The use of ultra-high-strength steels (UHS) has become more and more popular within last decade. Higher strength levels provide lighter and more robust steel structures, but UHS-steels are also more sensitive to surface defects (e.g. scratches). Practically this means that the critical crack size decreases when the strength increases. The aim of the study was to study if the formula of critical crack size is valid on forming processes of UHS-steels. Surface cracks with different depths were created by scratching the surface of the sheet by machining center. Effect of the scratch depth was determined by bending the specimens to 90 degrees. Bents were then visually compared and classified by the minimum achieved bending radius. Test materials used were direct quenched (DQ) bainitic-martensitic UHS steels (YS/TS 960/1000 and 1100/1250). Results from the bending tests were compared to the calculated values given by the formula of critical crack size.

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