A NON-DESTRUCTIVE EVALUATION INSTRUMENT FOR AXIAL LOAD MEASUREMENTS N. P. Vedula Staff Hardware Designer ManTech Advanced Systems International, Inc. 1000 Technology Drive, Suite 3310 Fairmont, WV 26554 C. Spyrakos Professor, Department of Civil Engineering West Virginia University Morgantown, WV 26506 P. Klinkhachom Professor, Department of ECE West Virginia University Morgantown, WV 26506 INTRODUCTION Assessment of stresses in axially loaded bridge members is designed to evaluate and determine the Ioad bearing capacity of the bridge. The Ioad bome by a bridge changes over time because of rust, creep, loosening of components and changing live Ioads. Cracks and other structural deficiencies are currently revealed primarily through costly, time-consuming, and somewhat tedious visual inspection methods. More accurate and advanced field inspection methods are needed to test and evaluate the structural stresses. This need for superior testing methods is tempered by present day budgetary constraints. Comprehensive techniques to monitor, detect, and rehabilitate incipient problems before they become dangerously deficient is paramount. A quantitative approach to bridge inspection would aid the periodic inspection process by supporting the compilation of an information database of the structural member's status. This data would provide an indication of the changing Ioad environment as the structure ages. Some Non-Destructive Evaluation (NDE) techniques do exist today for the measurement of axialloads in structural members; but, they involve the use of complex hardware and software to perform the measurements. Some popular methods in use are: Ultrasonic [Vary, 1976], Eddy currents [Junker and Clark, 1982], Acoustic Emission [Boyle, Sullivan, and Kraft, 1962], Acoustoelasticity [Shaik, Steele and Kino, 1982], and Photoelasticity [Daly and Riley, 1991]. In general, these methods do not offer an ideal Rel"leu· o(Progre.<.< 111 Quantitatfl'e NondestrltCifl'e Emluauon, Val. 16 Ed1ted by D.O. Thompson and D.E. Ch•menti, Plenum Press, New York. 1997 2199