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Three-dimensional nonlinear inelastic analysis of steel moment-frame buildings damaged by earthquake excitations

Citation

Carlson, Anders Elof (1999) Three-dimensional nonlinear inelastic analysis of steel moment-frame buildings damaged by earthquake excitations. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:02192014-110246738

Abstract

The Northridge earthquake of January 17, 1994, highlighted the two previously known problems of premature fracturing of connections and the damaging capabilities of near-source ground motion pulses. Large ground motions had not been experienced in a city with tall steel moment-frame buildings before. Some steel buildings exhibited fracture of welded connections or other types of structural degradation.

A sophisticated three-dimensional nonlinear inelastic program is developed that can accurately model many nonlinear properties commonly ignored or approximated in other programs. The program can assess and predict severely inelastic response of steel buildings due to strong ground motions, including collapse.

Three-dimensional fiber and segment discretization of elements is presented in this work. This element and its two-dimensional counterpart are capable of modeling various geometric and material nonlinearities such as moment amplification, spread of plasticity and connection fracture. In addition to introducing a three-dimensional element discretization, this work presents three-dimensional constraints that limit the number of equations required to solve various three-dimensional problems consisting of intersecting planar frames.

Two buildings damaged in the Northridge earthquake are investigated to verify the ability of the program to match the level of response and the extent and location of damage measured. The program is used to predict response of larger near-source ground motions using the properties determined from the matched response.

A third building is studied to assess three-dimensional effects on a realistic irregular building in the inelastic range of response considering earthquake directivity. Damage levels are observed to be significantly affected by directivity and torsional response.

Several strong recorded ground motions clearly exceed code-based levels. Properly designed buildings can have drifts exceeding code specified levels due to these ground motions. The strongest ground motions caused collapse if fracture was included in the model. Near-source ground displacement pulses can cause columns to yield prior to weaker-designed beams. Damage in tall buildings correlates better with peak-to-peak displacements than with peak-to-peak accelerations.

Dynamic response of tall buildings shows that higher mode response can cause more damage than first mode response. Leaking of energy between modes in conjunction with damage can cause torsional behavior that is not anticipated.

Various response parameters are used for all three buildings to determine what correlations can be made for inelastic building response. Damage levels can be dramatically different based on the inelastic model used. Damage does not correlate well with several common response parameters.

Realistic modeling of material properties and structural behavior is of great value for understanding the performance of tall buildings due to earthquake excitations.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:3D nonlinear inelastic analysis ; steel moment-frame buildings ; earthquake
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:
  • Unknown, Unknown
Defense Date:2 April 1999
Other Numbering System:
Other Numbering System NameOther Numbering System ID
EERL99-02
Additional Information:Also published as: Report (California Institute of Technology, Earthquake Engineering Research Laboratory) ; EERL 99-02
Record Number:CaltechTHESIS:02192014-110246738
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:02192014-110246738
Related URLs:
URLURL TypeDescription
http://resolver.library.caltech.edu/caltechEERL:1999.EERL-99-02Related DocumentEERL 99-02, available in CaltechAUTHORS
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8086
Collection:CaltechTHESIS
Deposited By: Kathy Johnson
Deposited On:05 Mar 2014 21:01
Last Modified:05 Mar 2014 21:01

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