Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS 2 p p εij εij 3 PEEQ Index = ( 3.17 ) ε where ij are the plastic strain components. y The triaxiality ratio and PEEQ index are also computed at different locations of the connection to provide additional means of comparing the analyzed connection configurations. The locations determined to have the highest fracture potential in the different analyzed configurations are in the weld toe region, near the interface of the weld metal and base metal. Weld matching effects Analyses with different weld matching conditions were carried out to investigate the joint response in terms of toughness demand. In detail, two models have been analysed: the first with overmatching welds characterized by mechanical properties very close to those of the experimental specimens; the second with matching welds in which the mechanical properties of welds are equal to those of the end plate material. Analyses with this different weld-matching conditions were carried out for: • the TM-2 specimens. The Tee stub models are designated ITS2-1 and ITS2-2, respectively, and the corresponding mechanical properties are collected in Table 3.8. A crack length equal to 1.30 mm has been considered in order to maximize the effect of residual stresses when included. • the TM-3 specimens. The Tee stub models are designated ITS3-1 and ITS3-2, respectively, and the corresponding mechanical properties are collected in Table 3.8. A crack length equal to 2.34 mm has been considered in order to maximize the effect of residual stresses when included. • the JB1-3 specimen. The CJ models are designated CJ3-1 and CJ3-2, respectively, and the corresponding mechanical properties are collected in Table 3.8. The same crack length of the TM3 specimen, equal to 2.34 mm, has been considered. For brevity, only the results of one specimen will be illustrated. The reaction force vs. the applied displacement for the TM-3 specimen is reported in Figure 3.39a. However differently from the overall behaviour, the corresponding CTOD demands are similar until a total displacement of 0.35 mm (see Figure 3.39b), from which the CTOD demand increases rapidly for the ITS3-1. 87
3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS For the joint configuration under exam, the matching weld condition, viz. the ITS3-2 case, appears to be the most beneficial in terms of fracture toughness demand. REACTION FORCE (kN) 88 700 600 500 400 300 200 100 0 Specimen Material ITS2-1 ITS2-2 ITS3-1 ITS3-2 CJ3-1 CJ3-2 E (MPa) fy (MPa) fu (MPa) Base metal 210000 265 600 Weld Metal 220000 520 640 Base metal 210000 265 600 Weld Metal 210000 265 600 Base metal 210000 307 517 Weld Metal 220000 520 640 Base metal 210000 307 517 Weld Metal 210000 307 517 Base metal 210000 307 517 Weld Metal 220000 520 640 Base metal 210000 307 517 Weld Metal 210000 307 517 Table 3.8. Parameters of the constitutive laws for TM-2, TM-3 and JB1-3 models (a) ITS3-1 ITS3-2 0 0.5 1 1.5 2 2.5 DISPLACEMENT (mm) CTOD (mm) 1 0.8 0.6 0.4 0.2 0 CTOD c (b) ITS3-1 ITS3-2 0 0.5 1 1.5 2 2.5 DISPLACEMENT (mm) Figure 3.39. Predicted force and CTOD vs. displacement of TM-3 specimens with overmatching (ITS3-1) and matching (ITS3-2) welds This behaviour can be explained through the equivalent plastic strain (PEEQ) distributions highlighted in Figure 3.40. During the loading process, identified by the two displacement levels (L1) and (L2), the yielded material in the weld metal corresponding to the ITS3-2 condition shields the crack tip from a stress increase.
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Dipartimento di Ingegneria Meccanic
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UNIVERSITÀ DEGLI STUDI DI TRENTO D
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Ai miei genitori
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INDEX 1 INTRODUCTION...............
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INDEX iii 4.10.3 Results of the PsD
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1.1 Introduction 1 1 INTRODUCTION I
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1. INTRODUCTION imposes precise con
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1. INTRODUCTION joints whilst 2D mo
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7 2 DUCTILITY AND SEISMIC RESPONSE
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2. DUCTILITY AND SEISMIC RESPONSE O
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5. SEISMIC BEHAVIOUR OF RC COLUMNS
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6. SUMMARY, CONCLUSIONS AND FUTURE
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Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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