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Earthquake response of steel braces and braced steel frames

Citation

Gan, Wenshui (1997) Earthquake response of steel braces and braced steel frames. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechThesis:03142014-103017013

Abstract

This thesis consists of three parts. Chapter 2 deals with the dynamic buckling behavior of steel braces under cyclic axial end displacement. Braces under such a loading condition belong to a class of "acceleration magnifying" structural components, in which a small motion at the loading points can cause large internal acceleration and inertia. This member-level inertia is frequently ignored in current studies of braces and braced structures. This chapter shows that, under certain conditions, the inclusion of the member-level inertia can lead to brace behavior fundamentally different from that predicted by the quasi-static method. This result is to have significance in the correct use of the quasi-static, pseudo-dynamic and static condensation methods in the simulation of braces or braced structures under dynamic loading. The strain magnitude and distribution in the braces are also studied in this chapter.

Chapter 3 examines the effect of column uplift on the earthquake response of braced steel frames and explores the feasibility of flexible column-base anchoring. It is found that fully anchored braced-bay columns can induce extremely large internal forces in the braced-bay members and their connections, thus increasing the risk of failures observed in recent earthquakes. Flexible braced-bay column anchoring can significantly reduce the braced bay member force, but at the same time also introduces large story drift and column uplift. The pounding of an uplifting column with its support can result in very high compressive axial force.

Chapter 4 conducts a comparative study on the effectiveness of a proposed non-buckling bracing system and several conventional bracing systems. The non-buckling bracing system eliminates buckling and thus can be composed of small individual braces distributed widely in a structure to reduce bracing force concentration and increase redundancy. The elimination of buckling results in a significantly more effective bracing system compared with the conventional bracing systems. Among the conventional bracing systems, bracing configurations and end conditions for the bracing members affect the effectiveness.

The studies in Chapter 3 and Chapter 4 also indicate that code-designed conventionally braced steel frames can experience unacceptably severe response under the strong ground motions recorded during the recent Northridge and Kobe earthquakes.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:steel braces ; steel frames ; earthquake engineering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Civil Engineering
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Hall, John F.
Thesis Committee:
  • Hall, John F. (chair)
  • Beck, James L.
  • Caughey, Thomas Kirk
  • Heaton, Thomas H.
  • Rosakis, Ares J.
Defense Date:6 December 1996
Other Numbering System:
Other Numbering System NameOther Numbering System ID
EERL96-06
Funders:
Funding AgencyGrant Number
CUREe (California Universities for Research in Earthquake EngineeringUNSPECIFIED
Earthquake Research Affiliates Program at CaltechUNSPECIFIED
Charles Lee Powell FoundationUNSPECIFIED
Harold Hellwig FoundationUNSPECIFIED
Record Number:CaltechThesis:03142014-103017013
Persistent URL:http://resolver.caltech.edu/CaltechThesis:03142014-103017013
Related URLs:
URLURL TypeDescription
http://resolver.caltech.edu/CaltechEERL:1996.EERL-96-06Related DocumentTechnical Report EERL 96-06 in CaltechAUTHORS
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8133
Collection:CaltechTHESIS
Deposited By: Kathy Johnson
Deposited On:18 Mar 2014 23:07
Last Modified:18 Mar 2014 23:07

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