Pounding of San Francisco–Type Soft-Story Midblock Buildings

2013 ◽  
Vol 29 (3) ◽  
pp. 1069-1089 ◽  
Author(s):  
Bruce Maison ◽  
Brian McDonald ◽  
Marko Schotanus
Keyword(s):  
San Francisco ◽  
Gap Size ◽  
Key Factors ◽  
Soft Story ◽  
Adjacent Buildings ◽  
Wood Frame

Presented is a study into the effects of pounding on the collapse performance of midblock wood-frame soft-story buildings. This study analyzed various pounding situations and found that it can change the collapse risk when compared to the risk of the same building having no adjacent buildings (no-pounding). Key factors include relative building strengths, weights, and separation (gap) distances. When the buildings had similar strengths, it was found that the risk was about the same as that for no-pounding, independent of building relative weights and/or gap size. When the strengths varied, it was found that pounding could change the risk of certain buildings. The risk increased in the stronger and decreased in the weaker buildings, and the risk was biased toward the no-pounding risk of the heavier buildings. The risk generally increased with larger building separation distances, but there were exceptions.

Pounding of San Francisco-Type Soft-Story Corner Buildings

2012 ◽  
Vol 28 (4) ◽  
pp. 1663-1686 ◽  
Author(s):  
Bruce Maison ◽  
David Bonowitz ◽  
Laurence Kornfield ◽  
David McCormick
Keyword(s):  
San Francisco ◽  
Upper Bound ◽  
Large Mass ◽  
Earthquake Response ◽  
Loma Prieta Earthquake ◽  
Design Procedures ◽  
Soft Story ◽  
Current Design ◽  
Wood Frame ◽  
Collapse Rate

We investigated 1920s-era four-story wood-frame corner buildings common to San Francisco, many of which were damaged in the city's Marina District during the 1989 Loma Prieta earthquake. Such buildings can have relatively weak and flexible first stories and are referred to as soft-story buildings. We calibrated two building computer models to simulate actual earthquake response. We then performed computer analysis to assess collapse performance under 22 hypothetical pounding situations of both as-built and retrofitted soft-story buildings. For this building type, we found that a typical pounding situation increased the collapse rate by 14%, and for retrofitted versions, pounding slightly decreased the collapse rate. However, there were factors that appear to significantly increase the rate, especially in combination: negligible building separations and multiple adjacent buildings having low effective damping and large mass. Based on the results, we outline an approximate way to account for pounding within the context of current design procedures. An upper bound on the pounding effect was found to be equivalent to about a 30% increase in demand.

Experimental Seismic Collapse Study of a Full-Scale, 4-Story, Soft-Story, Wood-Frame Building

2015 ◽  
Vol 21 (2) ◽  
Author(s):  
Pouria Bahmani ◽  
John W. van de Lindt ◽  
Gary L. Mochizuki ◽  
Mikhail Gershfeld ◽  
Steven E. Pryor
Keyword(s):  
Full Scale ◽  
Soft Story ◽  
Frame Building ◽  
Seismic Collapse ◽  
Wood Frame

Full-Scale Experimental Verification of Soft-Story-Only Retrofits of Wood-Frame Buildings using Hybrid Testing

2014 ◽  
Vol 19 (3) ◽  
pp. 410-430 ◽  
Author(s):  
Elaina Jennings ◽  
John W. van de Lindt ◽  
Ershad Ziaei ◽  
Pouria Bahmani ◽  
Sangki Park ◽  
...  
Keyword(s):  
Experimental Verification ◽  
Full Scale ◽  
Hybrid Testing ◽  
Soft Story ◽  
Frame Buildings ◽  
Wood Frame

Commentary on FEMA P-807 for Retrofit of Wood-Frame Soft-Story Buildings

2014 ◽  
Vol 30 (4) ◽  
pp. 1359-1380 ◽  
Author(s):  
Bruce Maison ◽  
Brian McDonald ◽  
David McCormick ◽  
Marko Schotanus ◽  
Jonathan Buckalew
Keyword(s):  
Lateral Force ◽  
Seismic Intensity ◽  
Building Performance ◽  
Seismic Evaluation ◽  
Site Class ◽  
Soft Story ◽  
Safety Margins ◽  
Lateral Strength ◽  
Independent Review ◽  
Wood Frame

The FEMA P-807 guideline titled Seismic Evaluation and Retrofit of Multi-Unit Wood-Frame Buildings with Weak First Stories is a new approach for building retrofit. It goes beyond current building codes and standards by quantifying performance in probabilistic terms. The authors performed an independent review of P-807, and the resulting commentary herein covers five topics: (1) building lateral force-drift (backbone) curves, (2) building interstory drift limits, (3) lateral strength requirements, (4) collapse safety margins, and (5) site class effects. It was concluded that P-807 may be an efficient way for relative ranking and selection of retrofit designs—but it has questionable accuracy for predicting actual building performance (i.e., the probability that a particular seismic intensity will result in a meaningful state of damage for a specific building).

Distributed Knee-Braced (DKB) System as a Complete or Supplemental Retrofit of Soft-story Wood-frame Buildings

2014 ◽  
Author(s):  
M. Gershfeld ◽  
C. Chadwell ◽  
J. van de Lindt ◽  
W. Pang ◽  
E. Ziaei ◽  
...  
Keyword(s):  
Soft Story ◽  
Frame Buildings ◽  
Wood Frame
Sign in / Sign up

Export Citation Format

Share Document