Presentation by Neel Khosa given during the Post-Tensioning Institute's 2011 Technical Conference. Topic is about the use of unbonded post-tensioned concrete in Target Field stadium, home of the Minnesota Twins MLB team.
Target Field – Minnesota TwinsPresenter by Neel Khosa, Vice President of AMSYSCO Inc.Presented at the 2011 Post-Tensioning Institute ‘Technical Conference’ for “Post-Tensioning, Design and Construction (part 1)” on May 3, 2011
Project Background, Construction Team, Design, Post-Tensioning
Coordination, Construction, Sustainability, Stadium Highlights, Grand Opening
Box Score is for the Minnesota Twins home opener against Boston Red Sox on April 12, 2010. (V) = BOS, (H) = MN
Walter P. Moore (structural engineer), Populous (architect), Mortenson Construction (construction manager), AMSYSCO Inc. (post-tensioning supplier)
Post-Tensioning supplier of Target Field was AMSYSCO, Inc. (www.amsyscoinc.com)
Quote from “Green ballpark showcases urban sustainability” Atlanta Business Chronicle by Giannina Smith
Stress 55 tendons with Main Concourse, 30 tendons with Club Level, 15 tendons with Suite Level, 30 tendons with Terrace Level.
Post-Tensioned Concrete Girders formed and poured ahead of time so that construction on upper levels could be expedited.
Construction Worker Parade
Unfurling of U.S. Flag on field
National anthem by construction workers and suppliers
Project Background<br />Minnesota Twins shared the Metrodome with Minnesota Vikings<br />1995 : Early plans to move<br />2005 : Deal between MN Twins and local Govt.<br />2006 : Minnesota state Govt. approved deal<br />2007 : Funding finalized and land acquired<br />2007 : Groundbreaking<br />Minnesota Twins vs. Boston Red Sox<br />Opening Day box score on April 12, 2010<br />
Project Background<br />Open Air Ballpark<br />
Project Background<br />Form Follows Function<br />Ballpark naming rights to Target Corporation<br />
Design of P.T.<br />Flat-plate Post-Tensionedsystem in Mezzanine level.<br />Post-Tensioned girdersin Concourses and some seating areas (with conventionally reinforced pan-formed beams and slabs).<br />
Design of P.T.<br />Post-Tensioning selected due to long-span capabilities and reducing concrete depth.<br />Heaviest Girder had 5,805 kips of Final P.T. Force.<br />Many girders required stage-stressing.<br />…<br /> “Site limitations and the ballpark layout dictated 28 main grandstand columns to be located directly atop the transit rail lines, so they were transferred with stage-stressed, post-tensioned girders that span up to 45 feet over the corridor to support the ballpark above.”<br />- Justin Barton (Walter P Moore)<br />
…<br />EXAMPLE OF STAGE-STRESSING IN BEAM SCHEDULE<br />
Post-Tensioning<br />SYSTEM<br />0.5” Diameter 270 ksi PC Strand.<br />Unbonded 50 ML HDPE plastic-sheathing.<br />Encapsulated anchorage system for corrosion-protection.<br />REQUIREMENTS<br />Stressing to 33 kips when concrete reached 3000 psi compressive strength.<br />Elongation range ±7%<br />P.T. Supports at 48” o.c.<br />
Example of Anchor Detail which illustrates the stage-stressing sequence of a transfer girder.<br />
Legend’s Club and Metropolitan Club are private lounges.</li></li></ul><li>Post-Tensioning<br />Suite Level and Terrace Level<br /><ul><li>Similar design but smaller than Club Level.
Cantilevered PT Girders had add tendons.</li></li></ul><li>Coordination<br />No repetition, every girder was unique.<br />Mortenson used BIM to model PT tendons using AMSYSCO’s CAD files.<br />Many conflicts solved during submittal process.<br />“The general who wins the battle makes many calculations before the battle is fought.”<br /> - Sun Tzu (Art of War)<br />
Coordination<br />North/South P.T. girders (in orange) poured and stressed first in order to build upper levels.<br />N/S girders required pockets to sleeves E/W tendons.<br />East/West P.T. beams (in green) and mild-reinforced beams poured second.<br />
Construction<br />In order to meet Opening Day 2010, Construction had to start before Design was completed.<br />Target Field was built over a BNSF Railroad corridor. Post-Tensioning eliminated the need for re-shoring which kept the railroad operational during construction.<br />
Construction<br />Project finished 3 months ahead of schedule.<br />TIME-LAPSE VIDEO of the construction of Target Field on YouTube.<br />Post-Tensioning was used as a cost-effective construction method.<br />Target Field’s seating was built in several phases.<br />
Target Field was the 2nd MLB stadium to receive LEED certification.<br />Earned 36 points towards LEED Silver status.<br />Over 30% of construction materials were made from recycled content.<br />70% of construction waste was recycled or diverted locally.<br />Sustainability<br />