Principal Investigators:
Antonio Nanni (Currently at Univ. Missouri-Rolla)
Charles E. Bakis (Engineering Science & Mechanics)
Andrew Scanlon (Civil and Environmental Engineering)
Researchers in the Composites Manufacturing Technology Center at Penn State are investigating the performance of fiber reinforced plastic (FRP) tendons and their anchors for the prestressed concrete construction industry. The goal of this project is to provide the U.S. Army Corps of Engineers (USACE) with an evaluation of some of the commercially available FRP tendon-anchor systems for potential application in prestressed concrete guideways for magnetically levitated, or "maglev," transportation systems. FRP's have been suggested as possible alternatives to steel reinforcement in areas of high magnetic flux. This evaluation is comprised of the following components: a literature survey; laboratory verification; analysis and modeling, including explanation of recorded values; determination of various properties such as tendon relaxation and anchor seating characteristics; and comparison of experimental results with trends predicted by finite element models.
Much research has already been done regarding the manufacture and mechanical response of various FRP tendons, but this research has been performed primarily outside of the USA and primarily by the various manufacturers using different testing methods. The purpose of this investigation is to provide a uniform, domestic evaluation of the mechanical performance of ten different aramid, glass, and carbon FRP tendons, with attention paid to the response and effects of the anchorage system recommended by the manufacturer. Examination of statically loaded tendons includes system assembly, anchor/tendon setting, slipping and/or gripping, and effects of the anchor on the tendon. Included with each specimen, in general, is a minimum of two sets of data comprised of fraction-of-second load, strain, and displacement readings during stressing and multiple minute readings during a three day period. Verification of some tendon-specific properties as established and provided by the manufacturers, including ultimate strength and modulus of elasticity, was obtained with tension tests to failure.
Anchoring systems examined in most cases permitted full prestressing of FRP tendons. Steel wedge anchors caused significantly more damage to FRP tendons than plastic wedges did. Regardless of wedge material, a grit is recommended for all gripping surfaces. Resin/epoxy potted anchors work well at prestressing levels but perform inconsistently at loads approaching tendon failure. It appears possible that some anchoring schemes may be interchangeable with certain tendon types. It was also determined that temperatures between -60 and +60 deg.C have no effect on the wedge anchoring systems examined.
Nanni, A., Bakis, C. E., O'Neil, E. F., and Dixon, T. O., "Performance of FRP Tendon-Anchor Systems for Prestressed Concrete Structures," PCI Journal, 41:34-44 (Jan./Feb. 1996).
Nanni, A., Bakis, C. E., O'Neil, E. F., and Dixon, T. O., "Short-Term Sustained Loading of FRP Tendon-Anchor Systems," Construction and Building Materials, 10:255-266 (1996).
Nanni, A., Bakis, C.E., and Dixon, T.O., "Evaluation of FRP Tendon-Anchor Systems for Prestressed Concrete Structures," Proc. 50th Ann. Conf. of the Composites Institute, Soc. Plastics Engineers, New York, 1995, pp. 21.B.1-21.B.6.
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To obtain more information on this research, please contact Prof. Charles E. Bakis (email: cbakis@psu.edu).
Last updated, 6 Nov 97. Copyright 1997, C. E. Bakis.