Performance of steel structures during the 1994 Northridge earthquake

Abstract

Abstract:The performance of concentrically braced steel frames and moment resisting steel frames during the January 17, 1994, Northridge, California, earthquake is examined. Most of the observations made during the reconnaissance visits confirmed the current knowledge on the inelastic response of these structural systems. This permits the anticipation of proper seismic behavior for buildings designed according to the seismic provisions that have been recently introduced in the Canadian building code and standard for steel structures. In some cases, however, the observed damage raised concerns that should be addressed in future investigations or next editions of these codes. Preventing potentially hazardous nonstructural damage, avoiding premature nonductile failures anywhere along the lateral load paths, limiting structural and nonstructural damage due to brace buckling, and accounting for the vertical ground motion are among those issues.Key words: earthquake, seismic, steel, concentrically braced frames, moment resisting frames, weld.R&um& : Dans cet article, on examine et commente le comportement de charpentes mCtalliques avec contreventement en treillis ou cadres rigides lors du stisme qui a eu lieu le 17 janvier 1994 5Northridge, en Californie. La majorit6 des observations faites lors des visites effectuCes sur le site confirment les connaissances dCji acquises sur le comportement non lintaire de ces systbmes structuraux lorsque soumis aux stismes. Ceci permet de croire que les bitiments conGus selon les dispositions sCismiques nouvellement introduites dans le code du bitiment canadien et la norme canadienne pour la calcul des structures d'acier seront adCquats dans 1'CventualitC de tremblements de terre importants. Dans certains cas, cependant, les dommages subis soulbvent des interrogations qui devraient faire l'objet d'Ctudes futures en vue dlamCliorer ces normes. Parmi les points qui devraient Ctre examinks, on retrouve la prCvention des dommages non-structuraux 5 risque, la prevention de ruptures subites et non-ductiles le long du cheminement des efforts induits par les charges latCrales, la rkduction des dommages imposCes aux ClCments structuraux ou non-structuraux lors du flambement des membrures diagonales des contreventements ainsi que la prise en compte des effets des mouvements verticaux du sol.Mots c l b : tremblement de terre, sCisme, charpentes mttalliques, contreventement en treillis, cadre rigide, soudure.

Economical-Structural Performance of Steel Moment Resisting Building Frames Using the Section Variation Technique

“…al. ;1995). One year later, nearly 50 steel buildings collapsed due to the Kobe earthquake (M6.9), confirming the possible weakness of these structures during seismic activity (Wai-Fah and Charles;.…”

Finite Element Analyses on Free From Damage Seismic Resisting Beam-to-Column Joints

“…Although effective and economically advantageous at the construction stage, the capacity design philosophy applied to traditional structural systems requires structural damages after seismic events, thus leading to significant economic losses [9][10][11][12][13].…”

Seismic Collapse Analysis of Concentrically-Braced Frames by the Ida Method

“…Many CBFs were destroyed and even collapsed in past earthquakes due to their poor performance. Regardless of the fact that numerous experimental and theoretical studies have been carried out for CBFs, the CBF system still suffers from various degrees of damage due to its poor ductility [3][4][5][6][7][8]. Thus, the CBFs constructed based on poor design guides in earlier days still attract the attention of researchers [9][10][11][12][13][14][15][16][17][18] CBFs in moderate seismic regions (MSRs) are typically designed using a response modification coefficient R equal to 3, which allows the seismic resistance detailing of a structure to be ignored, e.g., in the United States [19].…”