NEHRP Clearinghouse

Title
Evaluation of Two RC Buildings Retrofit with Steel Bracing.
File
PB92219682.pdf
Author(s)
Downs, R. E.; Hjelmstad, K. D.; Foutch, D. A.
Source
National Science Foundation, Washington, DC., November 1991, 355 p.
Identifying Number(s)
['UILU-ENG-91-2011', 'STRUCTURAL RESEARCH SER-563']
Abstract
Experimental and analytical studies were conducted to assess the contributions of two retrofit schemes to the performances of two RC buildings during the 1985 Mexico earthquake. The schemes used to strengthen the two buildings were similar in that diagonal steel braces and RC infill walls were used to stiffen and strengthen the existing RC frames. The schemes were different in that one had steel bracing in the interior of the building while the other had steel bracing on the exterior of the building. The evaluations of the retrofit schemes considered a variety of data including: (1) observations on earthquake damage from the 1979 Mexico earthquake, which occurred before the retrofit schemes were implemented; (2) ambient vibration measurements before and after retrofit; (3) observations on earthquake damage from the 1985 Mexico earthquake; (4) forced vibration tests after the 1985 earthquake; and (5) analytical studies using various models of the buildings based upon the building plans and other observations. The results of the studies indicate that the additional stiffness and strength provided by the retrofit elements were essential to the survival of the two buildings during the 1985 earthquake, that the effects of soil-structure interaction must be considered when designing retrofit systems for soft soil sites, and that connections play an important role in determining the effectiveness of the retrofit elements.
Keywords
; Earthquake damage; Retrofitting; Buildings; Computer programs; Reinforcement (Structures); Earthquake engineering; Reinforcing steels; Earthquake resistant structures; Structural vibration; Reinforcing materials; Dynamic response; Reinforced concrete; Soil-structure interactions; Finite element method; Concrete structures; Structural analysis; Mexico