Title: Sampling Techniques for Evaluating Large Concrete Structures: Part I

Author(s): Tamara Jadik Williams, Linda K. Nozick, Mary J. Sansalone, and Randall W. Poston

Publication: Structural Journal

Volume: 103

Issue: 3

Appears on pages(s): 399-408

Keywords: post-tensioned; sampling; test

DOI: 10.14359/15318

Date: 5/1/2006

Abstract:
Large structures present numerous possible test locations for a nondestructive evaluation. Challenges lie in selecting test locations, managing data collected, and stating testing results. This research evaluated the feasibility of using sampling methods to assist in these tasks. To assess the methods’ applicability, sampling was applied to data from actual structures that had previously been extensively tested. The researchers could then compare their predictions based on sampling to actual results from comprehensive testing. These studies demonstrated that sampling methods are useful at determining the number of samples and their locations. The results can effectively be stated as a confidence interval, presenting a range for the prediction based on an acceptable uncertainty. In Part I, a brief description of some sampling methods is given and the procedure (including simple random, stratified, and adaptive sampling) is applied to a post-tensioned bridge, which was nondestructively tested to locate air voids within grouted tendon ducts.