Final Report of the Getty Seismic Adobe Project

Seismic Stabilization of Historic Adobe Structures: Final Report of the Getty Seismic Adobe Project

E. Leroy Tolles, Edna E. Kimbro, Frederick A. Webster, and William S. Ginell


166 pages

PDF file size: 3.1 MB


This book describes tests performed on model adobe buildings to evaluate seismic damage mitigation techniques applicable to the retrofitting of historic and culturally significant adobe structures. Part of the Getty Seismic Adobe Project (GSAP), the three-year program outlined in this volume was designed to develop and test minimally invasive, inexpensive, and easily implemented methods of protecting such structures from severe earthquake damage. Small- and large-scale models were tested on computer-controlled shaking tables at Stanford University and at the IIZIS Earthquake Engineering Laboratory in the Republic of Macedonia, respectively. The authors identify typical failure modes of adobe structures and describe specific retrofit techniques to help minimize such failures. Extensive photographic documentation is included.

Table of Contents

  • Foreword
    Timothy P. Whalen
  • Preface
    William S. Ginell
  • Acknowledgments
  • Project Participants
  • Chapter 1: Background to the Getty Seismic Adobe Project
    • Getty Seismic Adobe Project Goals and Purpose
    • Life-Safety Issues for the Seismic Retrofit of Adobe Buildings
    • Conservation Issues for the Seismic Retrofit of Adobe Buildings
    • Seismic Performance and Seismic Retrofit
    • Project Approach
      • First-year activities
      • Second-year activities
      • Third-year activities
  • Seismic Retrofit Techniques
  • Overview of Tests
  • Description of Materials and Models
    • Adobe material
    • Model design and construction
    • Retrofit measures
    • Model similitude
    • Description of Test Procedure
      • Test setup
      • Instrumentation
      • Simulated earthquake motions
      • Documentation
  • Description of Models
    • Model 4 (SL = 5)
    • Model 5 (SL = 11)
    • Model 6 (SL = 11)
  • Test Results for Model 4
  • Test Results for Model 5
  • Test Results for Model 6
  • Summary of Test Results for Models 4–6
  • Layout of Model 7
  • Retrofit Measures
  • Summary of Test Results for Model 7
  • Layout of Models 8 and 9
  • Model 8 Retrofit Measures
  • Test Results for Model 8
  • Flexural Test of a Wall Element with Center-Core Reinforcement
  • Test Results for Model 9
  • Summary of Test Results for Models 8 and 9
  • Analysis of Model Test Results
    • Initial crack development (test levels II–IV)
    • Performance during moderate to strong seismic levels (test levels V–VII)
    • Performance during very strong seismic levels (test levels VIII–X)
    • Summary of performance of model buildings
  • Summary of Field Observations after the Northridge Earthquake
  • Comparison of Laboratory Results and Field Observations
  • Overview of Tests
  • Materials Tests
  • Dynamic Testing Procedures
  • Model Buildings
  • Model 10—Unretrofitted
    • Elastic response
    • Damage progression
    • Performance and collapse during severe ground motions
  • Model 11—Retrofitted
    • Elastic response
    • Damage progression
    • Performance during severe ground motions
  • Loads on Elements of the Retrofit System
    • Analysis and discussion of results
    • Comparison of elastic response
    • Comparison of damage progression
    • Comparison of performance during severe ground motions
  • Performance Observations and Summaries
  • Summary of Comparison of Performance of Small- and Large-Scale Models
  • Assessment of Retrofit Measures
  • Relative Model Performance

About the Authors

E. Leroy Tolles has worked on the seismic design, testing, and retrofit of adobe buildings since the early 1980s, specializing in the structural design and construction of earthen and wood buildings. He received his doctorate from Stanford University in 1989, where his work focused on the seismic design and testing of adobe houses in developing countries. He has led multidisciplinary teams to review earthquake damage after the 1985 earthquake in Mexico, the 1989 Loma Prieta earthquake, and the 1994 Northridge earthquake. He was principal investigator for the Getty Conservation Institute’s Getty Seismic Adobe Project and has coauthored numerous publications on seismic engineering. He is principal for ELT & Associates, an engineering and architecture firm in northern California.

Edna E. Kimbro is an architectural conservator and historian, specializing in research and preservation of Spanish and Mexican colonial architecture and material culture of early California. She studied architectural history at the University of California, Santa Cruz, and, in 1976, rehabilitated the last remaining adobe building of the Spanish Villa de Branciforte. Through the 1980s, she was involved in restoration of the Mission Santa Cruz for the California Department of Parks and Recreation. In 1989, she attended UNESCO’s International Centre for the Study of the Restoration and the Preservation of Cultural Property in Rome to study seismic protection of historic adobe buildings. In 1990, she became preservation specialist for the Getty Seismic Adobe Project. She is coauthor of a number of publications, and works as a project coordinator and preservation consultant for several historic sites in California.

Frederick A. Webster is a civil/structural engineer, working in California, who specializes in design, repair, and retrofitting of historic buildings. Since the early 1980s, he has researched, tested, lectured on, and designed adobe and rammed-earth buildings. He has also designed seismic retrofits, upgrades, repairs, and rehabilitation for historic and older adobes throughout the state. As part of the Getty Conservation Institute’s earthquake reconnaissance team, he performed post-earthquake damage surveys of twenty historic adobes following the 1994 Northridge earthquake, and of historic and cultural property following more recent earthquakes in Costa Rica. He is currently responsible for the structural design of several adobe buildings to be constructed as part of a large winery complex in Santa Barbara County.

William S. Ginell is a materials scientist with extensive experience in industry. In 1943, after graduating from the Polytechnic Institute of Brooklyn with a bachelor’s degree in chemistry, he became part of the secret research team at Columbia University working to develop the atomic bomb. After the war, he went on to receive his Ph.D. in physical chemistry from the University of Wisconsin and spent nine years at the Brookhaven National Laboratory on Long Island, New York, followed by twenty-six years working for aerospace firms in California. In 1984, he joined the Getty Conservation Institute and helped design the laboratories at the GCI’s Marina del Rey facility. He is currently senior conservation research scientist at the GCI Los Angeles and was project director of the Getty Seismic Adobe Project.