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Worldwide Dynamic Foundation Testing Codes and Standards

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Worldwide Dynamic Foundation Testing Codes and Standards Worldwide dynamic foundation testing codes and standards Beim, G. & Likins, G. Pile Dynamics, Inc. Keywords: dynamic foundation testing, codes, standards, specifications, safety factors, foundation design ABSTRACT: Ten years ago, a paper by Beim, J. et al (1998) compiled worldwide codes and standards pertaining to high and low strain dynamic testing. That work predicted the development and implementation of many new, normative documents in the years to follow. The present paper intends to verify the extent to which that prediction materialized. It updates the 1998 list of codes and standards to reflect their most current reviews, releases or editions and summarizes the authors’ process of identifying new codes and standards released throughout the world in the past 10 years. It also expands the 1998 code and standard review effort beyond high and low strain dynamic pile testing and into cross hole sonic logging and energy measurements on dynamic penetrometers for Standard Penetration Tests. Lastly, the paper discusses the implications of adoption of these codes and standards on foundation design and construction. For high strain dynamic tests, the paper reviews the differing philosophies of worldwide codes as applied to the effect of the employed foundation testing method and its reliability on the applicable factors of safety. Many codes have been adopting Load and Resistance Factor Design (LRFD) methods; these are briefly discussed. The overarching goal of this Codes and Standards review is to serve as a resource for foundation testers around the world. 1 INTRODUCTION implications of current foundation testing standards in design and construction are discussed in Section 3. This paper presents a representative overview of the Section 3.1 focuses on high strain dynamic load state of dynamic foundation testing codification and testing standards, and discusses safety factors. normalization throughout the world. When compared Section 4 concludes this work. to other construction procedures, dynamic foundation testing is a relatively new concept. Having seen most 1.1 Private sector versus government standard and of its development take place in the late 1960s and code development and enforcement early 1970s, it did not see worldwide standardization and codification efforts take place until the late In many countries, the National Government oversees 1980s and 1990s. By 1998 codes and standards had the regulatory development of codes, standards and proliferated sufficiently to warrant a compilation by specifications, as well as compliance enforcement Beim, J. et al. (1998). Other reviews (Goble, 2000; (Chabot, C. L., 2007). This commonly results in a Likins 2004) focused mostly on high strain dynamic single national code. By contrast, in the United States testing of foundations. This paper intends to update the development of building codes and standards is a and expand on the 1998 effort, focusing not only on mostly private sector effort, with non governmental high strain testing but also on crosshole sonic logging organizations playing a key role involuntary standards (CSL), pulse echo testing and energy measurements development. on dynamic penetrometers. The US Government established the National Codes, Standards and Specifications are developed Bureau of Standards in 1901; however USA and enforced in manners that vary with the countries manufacturers and the engineering community of where they originate. We start by discussing some of the early 20th century resisted the creation of a these differences and commenting on terminology. Bureau of Standards modeled after its European Section 2 updates and expands the international counterparts. The American Society for Testing compilation provided by Beim, J. et al. (1998). In and Materials (now ASTM International) had been 2.2, the authors focus in particular on the USA, their founded a few years before – in 1898 – in Philadelphia. country of practice, while 2.3 presents results of a During that period the American Society of Civil worldwide survey conducted by the authors. The Engineers and other professional organization were Science, Technology and Practice, Jaime Alberto dos Santos (ed) 689 also developing standard specifications for various of this paper, in the process of being revised. The industries. The by-laws of ASTM proclaimed its standard for low strain integrity testing, ASTM dedication to the development and unification of D-5882-07 (ASTM, 2007), was adopted originally standard methods of testing (ASTM, 1998). in 1995 and was revised in 2007 without major Private sector codes and standards developed in the changes. ASTM recommends normalization of US thus consist of procedural recommendations that results from Standard Penetration Tests (ASTM, aim to reflect state of the art and consensus industry 1999) and requires it when SPT results are used to practice, but, unlike many national codes, are not determine the liquefaction potential of sands (ASTM, enforceable until legislation to adopt them is passed 2004). D-4633-05 (ASTM, 2005), originally adopted by State or Local government. One exception to the in 1986 and substantially revised in 2005, states that private sector code development effort is the Standard the only accepted means of determining energy for Specification for Highway Bridges, developed by the normalization of N-values is by force and velocity American Association of State Highway Officials measurements. ASTM did not have a standard for CSL (AASHTO), which is a government entity. in 1998. ASTM D-6760-02, at the time of writing of this paper under revision without major changes 1.2 Nomenclature and usage being proposed, standardizes the CSL procedure and was adopted originally in 2002 (ASTM, 2002). Beim, J. et al. (1998) note that in most cases The American Association of State Highway specifications and standards describe testing and Transportation Officials (AASHTO) and the procedures, while codes tend to describe a design Federal Highway Administration (FHWA) jointly and construction practice. Specifications and produce design codes and guideline specifications standards often become part of more encompassing for foundation installation on transportation projects. construction codes such as the US-based International State Highway Departments (also known as Building Code (IBC, 2006). While we attempt to be Departments of Transportation or DOTs) then adopt consistent with the nomenclature used in that original AASHTO specifications, reference it, or modify the paper we heed the authors’ advice that sometimes guideline document. The Standard Specifications these documents are indistinguishable from each for Highway Bridges (AASHTO 2003) which was other, and acknowledge that some misnomers may in place in 1998 and included a section on dynamic occur in our work. Furthermore, the authors include testing, has been superseded by the AASHTO Load manuals of practice issued by industry organizations and Resistance Factor Design Bridge (LRFD) when discussing the USA. Design Specifications (AASHTO 2007). This newer Dynamic foundation testing often refers solely to document, as did the superseded one, allows load high and low strain dynamic testing; in the present testing by either dynamic or static methods. The paper, however, we include codes and standards document T-298-99 (AASHTO, 1999), originally relating to CSL and energy measurements on SPT published in 1993, standardizes the methodology tests. Low strain dynamic testing is sometimes for performing dynamic foundation testing on driven referred to as pulse echo testing in the industry and piles, drilled shafts, micropiles and continuous flight in this paper. auger cast piles. Most State DOTs (e.g. Kentucky, New Hampshire, Ohio, West Virginia and others) have provisions modeled after AASHTO for allowing 2 COMPILATION OF CODES AND high strain dynamic testing methods to confirm STANDARDS foundation quality. AASHTO’s draft proposed 2.1 United States of America construction specifications for drilled shafts is expected to specify that CSL be used as a regular In the United States, codes, standards and inspection method, while making reference to other specifications that normalize, accept or recommend non destructive test methods such as pulse echo testing nondestructive testing were already in existence in as well. Some State DOTs (for example West Virginia 1998. Ten years later, many existing standards have DOT, 2003) already specify the execution of crosshole seen updates and revisions and new publications have sonic logging in drilled shafts; others will likely emerged, some of them pertaining to crosshole sonic follow suit. logging. These documents have also become more Several building codes existed in the US up to widely referenced by both the public and private 1999. These are gradually being phased out, as the sectors. We discuss some of the most relevant ones three main regional building codes joined together in in the following paragraphs. 2000 to produce a national one (IBC, 2006) which ASTM standards are widely recognized and treats static load testing and dynamic pile testing as referenced around the world as minimum essentially equivalent. It is an Allowable Stress Design requirements and correct testing procedures. ASTM (ASD) code and assigns a global safety factor of 2.0 D-4945-00 (ASTM, 2000) standardizes procedures to either test. Similarly to the process of adoption for performing high strain dynamic testing. It was of AASHTO documents by States Departments of originally adopted in 1986 and is, at the time
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