Test Specimen #8. Cracks Initiated In This Specimen at ...
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Low Cycle Fatigue Tests and Fracture Analyses 16 Figure 11: Test Specimen #8. Cracks Initiated In This Specimen at Three Locations: At Very Small Weld Discontinuities Near One of the Runon-Runoff Tabs (White Arrow), At the Toe of the Reinforcing Fillet Weld (Red Arrow), and At the Weld Access Hole (Encircled Region) Figure 12: The Primary Fracture of Sample #8 Initiated by LCF From Very Small Weld Discontinuities (See Arrows) Brittle Fracture Subcritical Crack Growth LCF Initiation
Transcript of Test Specimen #8. Cracks Initiated In This Specimen at ...
Low Cycle Fatigue Tests and Fra
Figure 11: Test Specimen #8. Cracks Initiated In This Specimen at Three Locations: At Very Small Weld Discontinuities Near One of the Runon-Runoff Tabs (White Arrow), At the Toe of the Reinforcing
Fillet Weld (Red Arrow), and At the Weld Access Hole (Encircled Region)
Figure 12: The Primary F
Brittle Fracture
Subcritical Crack
GrowthIn n
LCF itiatiocture Analyses 16
racture of Sample #8 Initiated by LCF From Very Small Weld Discontinuities (See Arrows)
Low Cycle Fatigue Tests and Fracture Analyses 17
Figure 13: Cross-section at a Crack Located at The Beam Side Weld Toe of The Reinforcing Fillet Weld Located at the Bottom of the Lower Flange in Specimen #8. Also Note the Initiation of the
Cracking From a Small Weld Discontinuity Located Beneath the Surface (2% Nital Etch). Each of These Cracks Exhibits the Characteristics of LCF.
Low Cycle Fatigue Tests and Fracture Analyses 18
Figure 14: Cross-Section of the LCF Crack Initiated at The Weld Access Hole in Sample #8 (2% Nital Etch)
Figure 15: Scanning Electron Microscope Image of the Surface of the LCF Crack Shown in Figure 13
Low Cycle Fatigue Tests and Fracture Analyses 19
Figure 16: Top and Side View of The Lower Flange Crack in Sample #7
Low Cycle Fatigue Tests and Fracture Analyses 20
Figure 17: Specimen # 7 Weld Access Hole Fracture Surface. Approximately 42 Fatigue “Beach Marks” Were Visible On This Fracture Surface. The Spacing of These Fatigue Striations Was Used to
Estimate The Local Stress Which Produced The Fracture
Figure 18: Measured Fatigue Striation Spacing and Estimated Maximum Stress Intensity Factor and Peak Stress For The Weld Access Hole Crack In Sample #8 (See Figures 11, 14, and 15)
LCF: ~42 “Beach Marks” (Nf = 60 cycles)
Test 8 - Bottom Flange(Story Drift = 0.9%, Nf = 98 cycles, LCF From Weld Access
Hole)
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Low Cycle Fatigue Tests and Fracture Analyses 21
Figure 19: Measured Fatigue Striation Spacing and Estimated Maximum Stress Intensity Factor and Peak Stress For The Weld Access Hole Crack In Sample #7 (See Figure 17)
Sample 7 - Bottom Flange (Story Drift = 1.2%, Nf = 60,LCF Crack From Weld Access
Hole)
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Striation Spacing, inch
