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Defect tolerance for cast steel connections in braced frames / Tsutomu Iwashita in Journal of structural engineering, Vol. 138 N° 12 (Décembre 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 12 (Décembre 2012) . - pp. 1455–1464 Titre : Defect tolerance for cast steel connections in braced frames Type de document : texte imprimé Auteurs : Tsutomu Iwashita, Auteur ; Jeffrey A. Packer, Auteur ; Juan-Carlos De Oliveira, Auteur Année de publication : 2013 Article en page(s) : pp. 1455–1464 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Brittle  fracture  Cast  steel  connectors  Circular  hollow  section  braces  Defects  Fracture  toughness  Plastic  constraint  Toughness  scaling  model  Tubes Résumé : During the last decade, various steel casting products for steel building structures have been developed, such as connectors between brace members and gusset plates in braced frames. Some casting products are welded to steel sections such as tubular members and I-section members in building structures, where these members are expected to develop their capacity during a large-scale earthquake. In this situation, brittle fracture can be another concern of the casting products if there are defects in the connections. A study of defect tolerance for cast steel connections is therefore very important to prevent brittle fracture from weld defects or casting defects. This paper describes defect tolerances for cast steel connections in braced frames and explores the possibility of brittle fracture from assumed defects in typical cast steel connectors. A parametric study, which investigates the sensitivity of brittle fracture to defect size, defect location, and material mismatch effects, is described through cast steel connector models. A toughness scaling model is used for evaluating the occurrence of brittle fracture from assumed defects in the models. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000583 [article] Defect tolerance for cast steel connections in braced frames [texte imprimé] / Tsutomu Iwashita, Auteur ; Jeffrey A. Packer, Auteur ; Juan-Carlos De Oliveira, Auteur . - 2013 . - pp. 1455–1464. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 12 (Décembre 2012) . - pp. 1455–1464 Mots-clés : Brittle  fracture  Cast  steel  connectors  Circular  hollow  section  braces  Defects  Fracture  toughness  Plastic  constraint  Toughness  scaling  model  Tubes Résumé : During the last decade, various steel casting products for steel building structures have been developed, such as connectors between brace members and gusset plates in braced frames. Some casting products are welded to steel sections such as tubular members and I-section members in building structures, where these members are expected to develop their capacity during a large-scale earthquake. In this situation, brittle fracture can be another concern of the casting products if there are defects in the connections. A study of defect tolerance for cast steel connections is therefore very important to prevent brittle fracture from weld defects or casting defects. This paper describes defect tolerances for cast steel connections in braced frames and explores the possibility of brittle fracture from assumed defects in typical cast steel connectors. A parametric study, which investigates the sensitivity of brittle fracture to defect size, defect location, and material mismatch effects, is described through cast steel connector models. A toughness scaling model is used for evaluating the occurrence of brittle fracture from assumed defects in the models. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000583

Effect of plastic constraint on brittle fracture in steel / Tsutomu Iwashita in Journal of structural engineering, Vol. 138 N° 6 (Juin 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 6 (Juin 2012) . - pp. 744–752 Titre : Effect of plastic constraint on brittle fracture in steel : Evaluation using a toughness scaling model Type de document : texte imprimé Auteurs : Tsutomu Iwashita, Auteur ; Koji Azuma, Auteur Année de publication : 2012 Article en page(s) : pp. 744–752 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Brittle  fracture  Fracture  toughness  Plastic  constraint  Fracture  mechanics  J-integral  Weibull  stress  Ductile  crack Résumé : Over the past two decades, plastic constraint effects have been an issue of concern in both fracture mechanics and structural integrity research, and several methods have been proposed for considering loss of plastic constraint. This paper shows the ability of a simplified model to predict brittle fracture under low plastic constraint conditions. Fracture toughness tests are performed on single-edge notched bend (SENB) steel specimens with deep and shallow notches, as well as on double-edge notched tension and center-notched tension (CNT) specimens. When compared with SENB specimens with a deep notch, the CNT specimens show high fracture toughness as a result of the loss of plastic constraint at the crack tip. Here, the Weibull stress approach and a toughness scaling model (TSM) are used to consider the effects of the loss of plastic constraint on the fracture toughness of the specimens. The corrected fracture toughness values evaluated by the TSM are found to be close to the toughness values observed in the tests and to the values predicted by the Weibull stress approach. This paper also briefly discusses the effect of ductile crack growth on brittle fracture. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000507 [article] Effect of plastic constraint on brittle fracture in steel : Evaluation using a toughness scaling model [texte imprimé] / Tsutomu Iwashita, Auteur ; Koji Azuma, Auteur . - 2012 . - pp. 744–752. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 6 (Juin 2012) . - pp. 744–752 Mots-clés : Brittle  fracture  Fracture  toughness  Plastic  constraint  Fracture  mechanics  J-integral  Weibull  stress  Ductile  crack Résumé : Over the past two decades, plastic constraint effects have been an issue of concern in both fracture mechanics and structural integrity research, and several methods have been proposed for considering loss of plastic constraint. This paper shows the ability of a simplified model to predict brittle fracture under low plastic constraint conditions. Fracture toughness tests are performed on single-edge notched bend (SENB) steel specimens with deep and shallow notches, as well as on double-edge notched tension and center-notched tension (CNT) specimens. When compared with SENB specimens with a deep notch, the CNT specimens show high fracture toughness as a result of the loss of plastic constraint at the crack tip. Here, the Weibull stress approach and a toughness scaling model (TSM) are used to consider the effects of the loss of plastic constraint on the fracture toughness of the specimens. The corrected fracture toughness values evaluated by the TSM are found to be close to the toughness values observed in the tests and to the values predicted by the Weibull stress approach. This paper also briefly discusses the effect of ductile crack growth on brittle fracture. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000507