Mass Timber Rocking Panel Retrofit of a Four-Story Soft-Story Building with Full-Scale Shake Table Validation

Pouria Bahmani,Asif Iqbal,Douglas Rammer,John Van De Lindt

doi:10.3390/buildings7020048

Abstract

Soft-story wood-frame buildings have been recognized as a disaster preparedness problem for decades. There are tens of thousands of these multi-family three- and four-story structures throughout California and other cities in the United States. The majority were constructed between 1920 and 1970, with many being prevalent in the San Francisco Bay Area in California. The NEES-Soft project was a five-university multi-industry effort that culminated in a series of full-scale soft-story wood-frame building tests to validate retrofit philosophies proposed by (1) the Federal Emergency Management Agency (FEMA) P-807 guidelines and (2) a performance-based seismic retrofit (PBSR) approach developed within the project. Four different retrofit designs were developed and validated at full-scale, each with specified performance objectives, which were typically not the same. This paper focuses on the retrofit design using cross laminated timber (CLT) rocking panels and presents the experimental results of the full-scale shake table test of a four-story 370 m2 (4000 ft2) soft-story test building with that FEMA P-807 focused retrofit in place. The building was subjected to the 1989 Loma Prieta and 1992 Cape Mendocino ground motions scaled to 5% damped spectral accelerations ranging from 0.2 to 0.9 g.

Highlights

Full-scale whole-building tests have been performed around the world only 10 to 20 times [1,2].U.S.-based projects for the full-scale testing of light-frame wood buildings have increased significantly since the late 1990s as a result of the CUREE-Caltech Project [1,3] and projects related to the NationalScience Foundation (NSF) George E
The results showed that, for light-frame wood buildings typical of the 1980s to 1990s in California, only moderate damage resulted during a design-level earthquake, while significant and costly damage occurred during the maximum credible earthquake (MCE)
This paper focuses on the retrofit designs and validations using Cross Laminated Timber (CLT) rocking panels designed by applying the Federal Emergency Management Agency (FEMA) P-807 retrofit methodology

Summary

Introduction

Full-scale whole-building tests have been performed around the world only 10 to 20 times [1,2].U.S.-based projects for the full-scale testing of light-frame wood buildings have increased significantly since the late 1990s as a result of the CUREE-Caltech Project [1,3] and projects related to the NationalScience Foundation (NSF) George E. Full-scale whole-building tests have been performed around the world only 10 to 20 times [1,2]. U.S.-based projects for the full-scale testing of light-frame wood buildings have increased significantly since the late 1990s as a result of the CUREE-Caltech Project [1,3] and projects related to the National. A good summary is provided in a 2009 report prepared by the National Association of Home. Builders Research Center [4], but significant testing has occurred in the five years since that report. Filiatrault et al [3] tested a rectangular two-story house, but the specimen size was limited to the shake table dimensions but provided state-of-the-art test results. The building was designed in accordance with the 1988 Uniform Building

Methods

Results

Conclusion