Investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections

The presence of concrete slab in steel framing frame structures always makes retrofitting problems difficult. On the other hand, most of damages reported from Northridge earthquake (1994) has focused on the bottom flange of the beam. Therefore, in order to reduce the cost of retrofit, this operation...

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Autores principales:	mohammad bahirai, Mohsen Gerami
Formato:	article
Lenguaje:	FA
Publicado:	Iranian Society of Structrual Engineering (ISSE) 2019
Materias:	moment frame connection seismic retrofit heat treated beam section (hbs) reduced beam section (rbs) finite element method Bridge engineering TG1-470 Building construction TH1-9745
Acceso en línea:	https://doaj.org/article/8d2ea76351634fd5acf6e5d3d293477d
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spelling	oai:doaj.org-article:8d2ea76351634fd5acf6e5d3d293477d2021-11-08T15:51:46ZInvestigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections2476-39772538-261610.22065/jsce.2018.109293.1399https://doaj.org/article/8d2ea76351634fd5acf6e5d3d293477d2019-12-01T00:00:00Zhttps://www.jsce.ir/article_62638_2f772211870b5d832e0fe87cf9fecf89.pdfhttps://doaj.org/toc/2476-3977https://doaj.org/toc/2538-2616The presence of concrete slab in steel framing frame structures always makes retrofitting problems difficult. On the other hand, most of damages reported from Northridge earthquake (1994) has focused on the bottom flange of the beam. Therefore, in order to reduce the cost of retrofit, this operation can be done only at the bottom flange of the beam. In other words, by defining and applying a ductile fuse in the beam, by weakening the bottom flange of the bottom, it is possible to reduce the concentration of tension in the near-weld regions in connection and fracture failure in these areas. In this paper, a steel frame connection was analyzed numerically and after ensuring the modeling accuracy, it was under rehabilitation. Retrofit techniques have been made on the bottom flange of the beam. Two general "cut-off" and "heat" methods were considered to weaken the beam. In this research, incomplete penetration of the weld was placed in the bottom flange connection to the column as a deficiency in the joint. The modeling results showed that the connection with incomplete weld, underwent 4/4%, suffering a deflection in the weld area in the flange. In the specimens which were retrofitted asymmetrically, the possibility of brittle fracture in the weld region was decreased due to relocation of the plastic hinge in the weakened area of the beam. In the method of reducing the bottom flange, lateral buckling led to sudden decrease in flexural strength at 2.5 % inter story drift. In the heat-induction method accompanied with steel annealing, the out of buckling occurred at 5% drift. The retrofitted connection with this method showed a post elastic displacements of 3% and could be expected to be suitable for special moment frames.mohammad bahiraiMohsen GeramiIranian Society of Structrual Engineering (ISSE)articlemoment frame connectionseismic retrofitheat treated beam section (hbs)reduced beam section (rbs)finite element methodBridge engineeringTG1-470Building constructionTH1-9745FAJournal of Structural and Construction Engineering, Vol 6, Iss 4, Pp 71-94 (2019)
institution	DOAJ
collection	DOAJ
language	FA
topic	moment frame connection seismic retrofit heat treated beam section (hbs) reduced beam section (rbs) finite element method Bridge engineering TG1-470 Building construction TH1-9745
spellingShingle	moment frame connection seismic retrofit heat treated beam section (hbs) reduced beam section (rbs) finite element method Bridge engineering TG1-470 Building construction TH1-9745 mohammad bahirai Mohsen Gerami Investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections
description	The presence of concrete slab in steel framing frame structures always makes retrofitting problems difficult. On the other hand, most of damages reported from Northridge earthquake (1994) has focused on the bottom flange of the beam. Therefore, in order to reduce the cost of retrofit, this operation can be done only at the bottom flange of the beam. In other words, by defining and applying a ductile fuse in the beam, by weakening the bottom flange of the bottom, it is possible to reduce the concentration of tension in the near-weld regions in connection and fracture failure in these areas. In this paper, a steel frame connection was analyzed numerically and after ensuring the modeling accuracy, it was under rehabilitation. Retrofit techniques have been made on the bottom flange of the beam. Two general "cut-off" and "heat" methods were considered to weaken the beam. In this research, incomplete penetration of the weld was placed in the bottom flange connection to the column as a deficiency in the joint. The modeling results showed that the connection with incomplete weld, underwent 4/4%, suffering a deflection in the weld area in the flange. In the specimens which were retrofitted asymmetrically, the possibility of brittle fracture in the weld region was decreased due to relocation of the plastic hinge in the weakened area of the beam. In the method of reducing the bottom flange, lateral buckling led to sudden decrease in flexural strength at 2.5 % inter story drift. In the heat-induction method accompanied with steel annealing, the out of buckling occurred at 5% drift. The retrofitted connection with this method showed a post elastic displacements of 3% and could be expected to be suitable for special moment frames.
format	article
author	mohammad bahirai Mohsen Gerami
author_facet	mohammad bahirai Mohsen Gerami
author_sort	mohammad bahirai
title	Investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections
title_short	Investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections
title_full	Investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections
title_fullStr	Investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections
title_full_unstemmed	Investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections
title_sort	investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections
publisher	Iranian Society of Structrual Engineering (ISSE)
publishDate	2019
url	https://doaj.org/article/8d2ea76351634fd5acf6e5d3d293477d
work_keys_str_mv	AT mohammadbahirai investigationandcomparisonofsometechniquesinasymmetricallyretrofittingofsteelframeconnections AT mohsengerami investigationandcomparisonofsometechniquesinasymmetricallyretrofittingofsteelframeconnections
_version_	1718441682920275968

Investigation and comparison of some techniques in asymmetrically retrofitting of steel frame connections

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