Behr Architectural Glass to Resist Seismic and Extreme Climatic Events

1. Auflage 2009
ISBN: 978-1-84569-685-6
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 272 Seiten

Reihe: Woodhead Publishing Series in Civil and Structural Engineering

Glass is a popular cladding material for modern buildings. The trend for steel-framed, glass-clad buildings instead of those using traditional materials such as brick and concrete has inherent problems. These include, for example, the performance of architectural glass in extreme climatic events such as windstorms and heavy snow loads and also during earthquakes. This book reviews the state-of-the-art in glass and glazing technology to resist failure due to these natural events.Building code seismic requirements for architectural glass in the United States are considered first of all, followed by a chapter on glazing and curtain wall systems to resist earthquakes. The next two chapters discuss snow loads on building envelopes and glazing systems, and types and design of glazing systems to resist snow loads. Wind pressures and the impact of wind-borne debris are then considered in the next group of chapters which also review special types of glazing systems to resist windstorms. A final chapter reviews test methods for the performance of glazing systems during earthquakes and extreme climatic events.With its distinguished editor and team of contributors, Architectural glass to resist seismic and extreme climatic events is an essential resource for architects, structural, civil and architectural engineers, researchers and those involved in designing and specifying building glazing and cladding materials in areas where severe windstorms, snow and earthquakes are a threat. - Considers the state of the art in glass and glazing technology to resist failure due to extreme climatic events - Reviews specific building techniques and test methods to enhance glazing performance during snow storms, wind storms and earthquakes

Autoren/Hrsg.

Behr, Richard A.

Leseproben

1 Building code seismic requirements for architectural glass: the United States
R.E. Bachman    R. E. Bachman Consulting Structural Engineers, USA S.M. Dowty    S.K. Ghosh Associates Inc., USA Abstract
This chapter describes the current building code seismic requirements for architectural glass in the United States. The chapter first reviews the development of seismic requirements for nonstructural components in the United States. It then discusses the specific requirements for architectural glass which are treated as a subset of nonstructural components. These requirements primarily focus on providing an adequate clearance gap around the edge of the glass that would accommodate the anticipated horizontal relative displacements of a building during design earthquake events. Key words building codes seismic requirements nonstructural components architectural glass 1.1 Introduction
The most current building code enforced in most jurisdictions in the United States is the 2006 International Building Code (IBC, 2006). The 2006 IBC references the 2005 edition of the standard Minimum Design Loads for Buildings and Other Structures prepared by the American Society of Civil Engineers (ASCE, 2005) for its seismic provisions. ASCE 7-05 contains specific requirements for nonstructural components including requirements for architectural glass. There have been many significant examples of poor performance of architectural glass in past earthquakes (see Figs 1.1(a) and (b)). These have resulted in the development of new seismic standards and code requirements for architectural glass in the United States. This chapter provides the background on the development of US building code seismic requirements in Section 1.2 and an overview of what the building seismic requirements are in Section 1.3. In Section 1.4, the seismic requirements for nonstructural components are discussed and in Section 1.5, the specific requirements for architectural glass are described. Future trends in seismic requirements for architectural glass including performance-based design is described in Section 1.6, other sources of information are described in section 1.7, and references are provided in Section 1.8. 1.1 (a) Broken store windows after 1 October 1987 Whittier Narrows Earthquake (photos taken by Susan Dowty). (b) Broken curtain wall glazing after 2001 Nisqually Earthquake. (photo taken by Tom Reese, Seattle Times, March 2001) 1.2 Background
The most current building code enforced in most jurisdictions in the United States is the 2006 International Building Code (IBC, 2006). The 2006 IBC references the 2005 edition of the standard Minimum Design Loads for Buildings and Other Structures prepared by the American Society of Civil Engineers (ASCE, 2005) for its seismic provisions. The seismic provisions of ASCE 7-05 are, in turn, primarily based on the 2003 edition of the National Earthquake Hazard Reduction Program Recommended Provisions for Seismic Regulations for Buildings and Other Structures (NEHRP, 2003). ASCE 7-05 was developed by the ASCE 7 Standards Committee and its Seismic Task Committee. The NEHRP Recommended Provisions were developed by the Building Seismic Safety Council’s (BSSC) Provisions Update Committee (PUC) on behalf of the US Department of Homeland Security’s Federal Emergency Management Agency (FEMA). The seismic requirements for nonstructural components were developed by Technical Subcommittee 8 (TS-8) of the PUC. All ASCE and BSSC Committees are purely volunteer activities and are composed of many of the same professionals. The NEHRP Recommended Provisions were first published in 1985 and have been updated every 3 years since then. The first set of NEHRP Recommended Provisions were based on the Tentative Provisions for the Development of Seismic Regulations for Buildings, ATC 3-06 (ATC, 1978) published by the Applied Technology Council (ATC) for the National Bureau of Standards in 1978. This landmark document (one of the first developed by ATC) was prompted by the unexpected poor performance of buildings including nonstructural components (especially hospitals) during the 1971 San Fernando Earthquake. ATC 3-06 has formed the basis for many of the concepts contained in the NEHRP Recommended Provisions and the ASCE 7 standard including those for nonstructural components. Special requirements were included for those components that need to function after design earthquake ground motions that included seismic certification of nonstructural components by shake table tests, experience data, or sophisticated analysis. The NEHRP Provisions feed directly into the ASCE 7 development process and ASCE 7 in turn serves as a primary referenced standard in the IBC. The seismic design provisions of the 2006 IBC are based on those of ASCE 7-05 and make extensive reference to that standard. In fact, almost all of the seismic design provisions are adopted through reference to ASCE 705. The only seismic provisions included in the text of the 2006 IBC are related to ground motion, soil parameters, and determination of seismic design category (SDC), as well as definitions of terms actually used within those provisions and the four exceptions under the scoping provisions. Figure 1.2 illustrates the relationship between the three documents. 1.2 Relationship between documents. 1.3 Current building code seismic requirements
The structural requirements of the 2006 IBC, which include seismic requirements, are contained in IBC Chapters 16 to 23. Load combinations and load factors, including those containing seismic loads, are provided in Section 1604 while specific requirements for seismic loads are contained in Section 1613. Chapter 17 contains requirements for testing and inspection including special requirements for nonstructural components. Chapter 18 provides requirements for foundations and Chapters 19 to 23 contain structural element and connection detailing requirements for concrete, aluminum, masonry, steel, and wood. Both the foundation and material requirements have special requirements dealing with seismic loadings. The seismic requirements found in Section 1613 of the 2006 IBC are rather minimal because of the reliance on referencing ASCE 7-05 seismic provisions. It should be noted that the seismic requirements found in the 2000 and 2003 IBC were much more extensive. The Section 1613 seismic requirements that are provided are as follows: • General charging language • Definitions • Design ground motion parameter definitions and design ground motion maps • Site soil condition classification definitions and site amplification factors • Seismic Design Categories based on site ground motions and occupancy • Reference to ASCE 7-05 for all seismic design criteria requirements • Two minor alternatives to the ASCE 7-05 seismic design criteria requirements. The first alternative permits structural diaphragms to be assumed to be flexible under certain conditions while the second alternative permits increased height limits for steel ordinary concentrically braced frames and moment frames used in conjunction with seismic isolation systems provided the systems are designed to remain elastic during design earthquake level ground motions. The ground motion values used for the design of buildings are also used for the design of nonstructural components. Also, the Seismic Design Category that a given building is assigned is one of the key factors that determines the seismic requirements for nonstructural components. 1.3.1 Maximum design earthquake ground motion parameters and ground motion maps
The 2006 IBC defines earthquakes in terms of maximum considered earthquake (MCE) ground motion parameters. The MCE design parameters are defined as those that have a 2% probability of exceedance in 50 years, but with deterministic limits in areas where earthquake sources and return periods are well known. The MCE design parameters are defined for a rock site and are specified as 5% damped spectral ordinates at periods of 0.2 seconds (short period) and at a period of 1.0 second (long period). These spectral values are denoted as Ss and S1, respectively. Contour maps developed by the United States Geological Survey (USGS) are provided in Chapter 16 and provide values of Ss and S1 for all locations in the United States. The values of Ss range from 0.0 to 3.0 g while the values of S1 range from 0.0 to 1.25 g. Spectral values are also available at a USGS website (http://earthquake.usgs.gov/research/hazmaps/design/index. php), where values are provided based on the latitude and longitude of the site. In areas of high seismicity, where contour values change rapidly, the website is the only accurate way to determine the MCE design parameters. 1.3.2 Site class definitions and site amplification...