Bracing systems for seismic retrofitting of steel frames

L. Di Sarno, Amr S. Elnashai

Research output: Contribution to journalArticle

71 Citations (Scopus)

Abstract

The present study assesses the seismic performance of steel moment resisting frames (MRFs) retrofitted with different bracing systems. Three structural configurations were utilized: special concentrically braces (SCBFs), buckling-restrained braces (BRBFs) and mega-braces (MBFs). A 9-storey steel perimeter MRF was designed with lateral stiffness insufficient to satisfy code drift limitations in zones with high seismic hazard. The frame was then retrofitted with SCBFs, BRBFs and MBFs. Inelastic time-history analyses were carried out to assess the structural performance under earthquake ground motions. Local (member rotations) and global (interstorey and roof drifts) deformations were employed to compare the inelastic response of the retrofitted frames. It is shown that MBFs are the most cost-effective bracing systems. Maximum storey drifts of MBFs are 70% lower than MRFs and about 50% lower than SCBFs. The lateral drift reductions are, however, function of the characteristics of earthquake ground motions, especially frequency content. Configurations with buckling-restrained mega-braces possess seismic performance marginally superior to MBFs despite their greater weight. The amount of steel for structural elements and their connections in configurations with mega-braces is 20% lower than in SCBFs. This reduces the cost of construction and renders MBFs attractive for seismic retrofitting applications.

Original languageEnglish (US)
Pages (from-to)452-465
Number of pages14
JournalJournal of Constructional Steel Research
Volume65
Issue number2
DOIs
StatePublished - Feb 1 2009

Fingerprint

Retrofitting
Steel
Buckling
Earthquakes
Roofs
Costs
Hazards
Stiffness

All Science Journal Classification (ASJC) codes

  • Building and Construction
  • Civil and Structural Engineering
  • Mechanics of Materials
  • Metals and Alloys

Cite this

Di Sarno, L. ; Elnashai, Amr S. / Bracing systems for seismic retrofitting of steel frames. In: Journal of Constructional Steel Research. 2009 ; Vol. 65, No. 2. pp. 452-465.
@article{938c88cf310c464d961f8e677cd7aa7a,
title = "Bracing systems for seismic retrofitting of steel frames",
abstract = "The present study assesses the seismic performance of steel moment resisting frames (MRFs) retrofitted with different bracing systems. Three structural configurations were utilized: special concentrically braces (SCBFs), buckling-restrained braces (BRBFs) and mega-braces (MBFs). A 9-storey steel perimeter MRF was designed with lateral stiffness insufficient to satisfy code drift limitations in zones with high seismic hazard. The frame was then retrofitted with SCBFs, BRBFs and MBFs. Inelastic time-history analyses were carried out to assess the structural performance under earthquake ground motions. Local (member rotations) and global (interstorey and roof drifts) deformations were employed to compare the inelastic response of the retrofitted frames. It is shown that MBFs are the most cost-effective bracing systems. Maximum storey drifts of MBFs are 70{\%} lower than MRFs and about 50{\%} lower than SCBFs. The lateral drift reductions are, however, function of the characteristics of earthquake ground motions, especially frequency content. Configurations with buckling-restrained mega-braces possess seismic performance marginally superior to MBFs despite their greater weight. The amount of steel for structural elements and their connections in configurations with mega-braces is 20{\%} lower than in SCBFs. This reduces the cost of construction and renders MBFs attractive for seismic retrofitting applications.",
author = "{Di Sarno}, L. and Elnashai, {Amr S.}",
year = "2009",
month = "2",
day = "1",
doi = "10.1016/j.jcsr.2008.02.013",
language = "English (US)",
volume = "65",
pages = "452--465",
journal = "Journal of Constructional Steel Research",
issn = "0143-974X",
publisher = "Elsevier BV",
number = "2",

}

Bracing systems for seismic retrofitting of steel frames. / Di Sarno, L.; Elnashai, Amr S.

In: Journal of Constructional Steel Research, Vol. 65, No. 2, 01.02.2009, p. 452-465.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Bracing systems for seismic retrofitting of steel frames

AU - Di Sarno, L.

AU - Elnashai, Amr S.

PY - 2009/2/1

Y1 - 2009/2/1

N2 - The present study assesses the seismic performance of steel moment resisting frames (MRFs) retrofitted with different bracing systems. Three structural configurations were utilized: special concentrically braces (SCBFs), buckling-restrained braces (BRBFs) and mega-braces (MBFs). A 9-storey steel perimeter MRF was designed with lateral stiffness insufficient to satisfy code drift limitations in zones with high seismic hazard. The frame was then retrofitted with SCBFs, BRBFs and MBFs. Inelastic time-history analyses were carried out to assess the structural performance under earthquake ground motions. Local (member rotations) and global (interstorey and roof drifts) deformations were employed to compare the inelastic response of the retrofitted frames. It is shown that MBFs are the most cost-effective bracing systems. Maximum storey drifts of MBFs are 70% lower than MRFs and about 50% lower than SCBFs. The lateral drift reductions are, however, function of the characteristics of earthquake ground motions, especially frequency content. Configurations with buckling-restrained mega-braces possess seismic performance marginally superior to MBFs despite their greater weight. The amount of steel for structural elements and their connections in configurations with mega-braces is 20% lower than in SCBFs. This reduces the cost of construction and renders MBFs attractive for seismic retrofitting applications.

AB - The present study assesses the seismic performance of steel moment resisting frames (MRFs) retrofitted with different bracing systems. Three structural configurations were utilized: special concentrically braces (SCBFs), buckling-restrained braces (BRBFs) and mega-braces (MBFs). A 9-storey steel perimeter MRF was designed with lateral stiffness insufficient to satisfy code drift limitations in zones with high seismic hazard. The frame was then retrofitted with SCBFs, BRBFs and MBFs. Inelastic time-history analyses were carried out to assess the structural performance under earthquake ground motions. Local (member rotations) and global (interstorey and roof drifts) deformations were employed to compare the inelastic response of the retrofitted frames. It is shown that MBFs are the most cost-effective bracing systems. Maximum storey drifts of MBFs are 70% lower than MRFs and about 50% lower than SCBFs. The lateral drift reductions are, however, function of the characteristics of earthquake ground motions, especially frequency content. Configurations with buckling-restrained mega-braces possess seismic performance marginally superior to MBFs despite their greater weight. The amount of steel for structural elements and their connections in configurations with mega-braces is 20% lower than in SCBFs. This reduces the cost of construction and renders MBFs attractive for seismic retrofitting applications.

UR - http://www.scopus.com/inward/record.url?scp=56949097490&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=56949097490&partnerID=8YFLogxK

U2 - 10.1016/j.jcsr.2008.02.013

DO - 10.1016/j.jcsr.2008.02.013

M3 - Article

VL - 65

SP - 452

EP - 465

JO - Journal of Constructional Steel Research

JF - Journal of Constructional Steel Research

SN - 0143-974X

IS - 2

ER -