Vibration Control During Museum Construction Projects

Abstract

As vibrations caused by heavy construction at museums are potentially harmful to museum buildings and artwork, the protection of museum objects calls for a reliable method of vibration control. This article provides background information on vibrations and their effects on humans, buildings, and artwork, along with recommending conservative limits for protection of buildings and artwork from construction vibrations. Humans can perceive low levels of vibration before damaging levels are reached, and typical ambient (background) vibrations in museums can approach recommended limits. Research also shows that during transit, art objects are exposed to vibration levels much higher than recommended limits and damage rarely occurs. The greatest risks for damage to art objects during construction are from light objects “walking” on smooth surfaces; from the resonance of objects with natural frequencies similar to construction vibrations; and from vibratory motion of extremely fragile objects or those with serious pre-existing weaknesses. On the basis of research and the authors' experience, a general methodology for vibration control during museum construction projects is introduced—a methodology that reliably protects the museum while not unduly constraining the construction. Two examples of large-scale implementations are described to illustrate this methodology.

Résumé—Puisque les vibrations causées par des constructions importantes dans les musées sont potentiellement nuisibles aux bâtiments et aux œuvres d'art, la protection des objets muséaux requière une méthode fiable pour le contrôle des vibrations. Cet article offre des informations de contexte sur les vibrations et leurs effets sur les gens, les bâtiments et les œuvres d'art; il recommande également des limites conservatives pour la protection des bâtiments et des œuvres d'art contre les vibrations. Les gens peuvent percevoir des niveaux bas de vibrations avant que des effets nuisibles soient atteints et que ces vibrations de fond, qui sont communes, approchent les limites recommandées pour les musées. Des recherches montrent également que durant le transport, les œuvres d'art sont exposées à des niveaux de vibration bien supérieurs aux limites recommandées; néanmoins les dommages sont rares. Les risques de dommage les plus élevés pour les œuvres d'art durant les phases de constructions concernent les objets légers se déplaçant sur des surfaces lisses; la résonance des objets ayant des fréquences naturelles similaires aux vibrations causées pendant la construction; et le mouvement vibratoire d'objets extrêmement fragiles ou de ceux ayant de sérieuses faiblesses préexistantes. Basée sur la recherche et l'expérience des auteurs, une méthodologie générale de contrôle des vibrations lors de projets de construction muséaux est présentée – une méthodologie qui protège efficacement le musée sans contraindre la construction outre mesure. Deux exemples de mise en application à grande échelle sont décrits pour illustrer cette méthodologie.

Resumen—Dado que las vibraciones causadas por las obras de construcción en los museos son potencialmente dañinas para los edificios y para las obras de arte, la protección de los objetos de museo requiere de métodos confiables para controlar las vibraciones. Este articulo proporciona antecedentes informativos sobre las vibraciones y sus efectos en personas, en edificios y en obras de arte, y recomienda limites razonables para la protección de los mismos. Los seres humanos pueden percibir niveles de vibración bajos antes de que estos alcancen niveles de daño, y las vibraciones ambientales típicas en los museos puedan llegar a los limites recomendables. La investigación también muestra que durante el transito, los objetos están expuestos a niveles de vibración mayores que los limites recomendados y sin embargo raramente ocurren daños. Los mayores riesgos de daño para los objetos de arte durante la construcción ocurren cuando los objetos livianos “caminan” sobre las superficies lisas; cuando la resonancia de objetos con frecuencias naturales son similares a las vibraciones de la construcción, y cuando hay movimientos vibratorios de objetos extremadamente frágiles o de aquellos con debilidad seria pre-existente. Sobre la base de la investigación y de la experiencia de los autores se presenta una metodología general para controlar las vibraciones durante los proyectos de construcción, la cual protege de modo confiable sin poner demasiadas restricciones a la construcción. Para ilustrar la metodología, se describen dos ejemplos de implementación de proyectos a gran escala.

Resumo—Uma vez que as vibrações causadas pela construção pesada em museus são potencialmente prejudiciais para os edifícios de museus e para as obras de arte, a proteção dos objetos do museu exige um método confiável de controle de vibração. Este artigo fornece informações básicas a respeito das vibrações e seus efeitos sobre os seres humanos, os edifícios e as obras de arte, além de recomendar limites conservadores para a proteção de edifícios e obras de arte das vibrações de construção. Os seres humanos podem perceber baixos níveis de vibração antes que níveis prejudiciais sejam alcançados e as vibrações típicas do ambiente (fundo) nos museus podem se aproximar dos limites recomendados. A pesquisa também mostra que, durante o transporte, os objetos de arte são expostos a níveis de vibração muito mais elevados do que os limites recomendados e raramente ocorrem danos. Os maiores riscos de danos aos objetos de arte durante a construção são de que os objetos leves “andem” em superfícies lisas; de ressonância de objetos com freqüências naturais semelhantes às vibrações da construção; e de movimento vibratório de objetos extremamente frágeis ou daqueles com graves fragilidades pré-existentes. Com base nas pesquisas e na experiência dos autores é introduzida uma metodologia geral para o controle de vibração durante os projetos de construção de museus – uma metodologia que protege o museu com segurança embora não restrinja indevidamente a construção. São descritos dois exemplos de implementações em grande escala para ilustrar a metodologia.

Keywords:

• vibration
• shock
• construction
• museums
• artwork
• monitoring
• vibration limits

Acknowledgments

The authors gratefully acknowledge the staffs at The Art Institute of Chicago and The Saint Louis Art Museum for their assistance and cooperation during the referenced construction projects.

Notes

1 In this article, all vibration magnitudes are expressed in terms of peak particle velocity, with units of millimeters per second with inches per second in parentheses. In other words, this is the speed of motion of a particle at any moment in time. Vibration magnitudes can also be expressed in terms of displacement (millimeters or inches) and acceleration (meters per square second or g's or inches per square second). Most research on building damage from shock (blast) and vibration has been reported in terms of velocity. Most research on the effects of shock and vibration on artwork has been reported in terms of acceleration. The authors have converted (approximately) the acceleration data to velocity by assuming a predominant frequency of 20 Hz, a typical response frequency for older museum structures.

2 The USBM limit was developed for earthborn vibrations affecting residential-type buildings, with monitoring locations on the ground next to the base of the structure, not on a wall or floor of the building or on an object within the building. Actual vibration levels within a building can be considerably greater than on the ground at the base of the building due to dynamic amplification effects. Amplification occurs when the natural frequency of the structure, or a portion of the structure, is close to the frequency of the vibration input (this effect is called resonance). Actual response due to amplification can be several times the magnitude of the ground vibration. Applying the vibration limits cited above to the case where vibrations are measured on the actual structural elements or on objects inside the building should be conservative because the measured response includes any amplification effects.

Additional information

Notes on contributors

Arne P. Johnson

Arne P. Johnson is a licensed structural engineer and principal with 22 years of experience at Wiss, Janney, Elstner Associates, Inc. He holds a B.S. in Civil Engineering from the University of Illinois at Urbana-Champaign and a M.S. in Structural Engineering from the University of California at Berkeley. Mr. Johnson's areas of practice include structural evaluation, testing, and rehabilitation for structures of all types, including historic structures, stadiums, and museums. Address: Wiss, Janney, Elstner Associates, Inc., 330 Pfingsten Road, Northbrook, IL 60062, USA. Email: [email protected].

W. Robert Hannen

W. Robert Hannen joined Wiss, Janney, Elstner Associates, Inc. in 1976 with a Bachelor of Science in Geology from Northern Illinois University. He earned a Master's Degree in Geotechnical Engineering from the University of Illinois Circle Campus in 1982 and became a licensed Professional Engineer in Illinois in 1986. Trained under Jack Wiss, Mr. Hannen has spent his entire career measuring and evaluating vibrations and developing remote vibration and structural health monitoring systems. Address: Wiss, Janney, Elstner Associates, Inc., 330 Pfingsten Road, Northbrook, IL 60062, USA. Email: [email protected].

Frank Zuccari

Frank Zuccari is a 1975 graduate of the Cooperstown Graduate for Conservation of Historic and Artistic Works. He joined the Art Institute of Chicago in 1986 as Senior Paintings Conservator, specializing in the conservation of old master and 19th century paintings and has headed the Department of Conservation since 1993. Before going to the Art Institute, Mr. Zuccari was a staff conservator at the Museum of Fine Arts in Boston and before that at the Kimbell Art Museum in Fort Worth. From 1978 to 1980 he was Andrew W. Mellon Fellow in Paintings Conservation at the Metropolitan Museum of Art. Address: The Art Institute of Chicago, Department of Conservation, 111 South Michigan Avenue, Chicago, IL 60603, USA. Email: [email protected].