New Centralizer for Tendon and Rebar Alignment Pieresearch has introduced the Unibar, a new specially-designed centralizer for use with tendon and rebar elements for earth support systems. To achieve proper design strength in any drilled and grouted hole, the tendon or rebar anchor material must be centered in the hole to allow minimum coverage throughout the length of the element. Made of durable, noncorrosive plastic, this easily installed, light weight and economical centralizer contributes to the quality control of the construction process. The Unibar centralizer consists of two identical halves that snap together. They can be attached with zip ties or tie wire; no nuts or bolts are required. The centralizer will accommodate single-bar, multi-bar, standard strand or encapsulated (DCP) anchors, and can be used for steel or plastic pipe applications. Unibar centralizers are ideal for soil nails, rock and soil anchors, micropiles and auger-cast piles with single tension bars. For more information, visit www.pieresearch.com. Tapertube Piles at South Street Seaport In 2012, Hurricane Sandy significantly damaged the South Street Seaport historic district on New York’s East River. The Seaport area is being redeveloped in compliance with new flood plain maps. Much of the work is underway, including a new building and its pile foundation. The Tapertube® piles used for this project offered significant advantages, including higher capacity and faster driving, which lowered project costs. The patented Tapertube piles are manufactured by DFP Foundation Products. For the Seaport installation, the number of piles was cut from Tapertube steel piles are tapered from the tip end to a given length of larger diameter; they are extended by welding straight pipe to the tapered end. The taper increases the load capacity for the friction pile. The increase in capacity, in addition to side friction and toe bearing, comes from “cylindrical cavity expansion.” Essentially, for the tapered section to further penetrate the soil it must displace the surrounding soil to enlarge the cavity and therefore becomes a third mechanism in load capacity. Tapertube piles are made from 50 ksi steel. The driving point is a steel casting made to ASTM A-148 grade 90/60 in tip diameters of 8 in (203.2 mm) and larger. Top or butt diameters range from 12 to 24 in (304.8 to 609.6 mm). Wall thickness may vary from .188 to .625 in (4.7 mm to 15.8 mm). 130 • DEEP FOUNDATIONS • NOV/DEC 2016 846 opened-ended piles, each 24 in (609.6 mm) and .5 in (12.7 mm) thick, to 810 Tapertube piles, which lowered the total cost. Of the 810 piles, 434 are 150-ton capacity piles. The other 376 are 250-ton capacity piles. The main pier was designed by CH2M Hill, and the second ancillary pier was designed by McLaren. Tapertube piles have been used for over 100 projects; among them are John F. Kennedy International Airport, LaGuardia Airport, NYSDOT bridges, PennDOT bridges, MassDOT bridges, DelDOT bridges, and ODOT bridges. In addition, they are used for NYMTA projects, marine projects and numerous private projects in the Northeast U.S. and several in Bermuda.
