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CASE STUDY Commercial ©2013 Foundaon Supportworks®, Inc. All Rights Reserved. Case Number 071913 Project: Locaon: Date: FSU Conradi Building Demolion Tallahassee, FL April 2013 Challenge: The aged and outdated Conradi Building, constructed in 1956, was planned to be demolished to provide space for addional on-campus parking. The exisng three-story structure with a basement was located adjacent to a major thoroughfare. In order to allow demolion of the building, yet sll provide support to the road, it was proposed that secons of the north basement wall would remain where grade elevaon of the retained soils matched the roadway. An anchoring system would be required to provide the overturning resistance for the wall. The basement wall would then receive aesthec improvements and remain as a permanent retaining structure. 10-inch diameter holes cored for eback installaon Helical anchors installed from inside basement prior to demolion Post demolion basement wall with three helical ebacks and one Geo-Lock® anchor through a pilaster View from roadway showing the distance from the road to the basement wall Project Summary Architect: Geotechnical Engineer: Structural Engineer: General Contractor: Cerfied Installer: Products Installed: Hicks Nation Ardaman & Associates David H. Melvin Childers Construction Alpha Foundation Specialists, Inc. (24) Foundation Supportworks® Model 150 Helical Tiebacks, 8”-10” Lead Section, Installed to Lengths of 21 feet, Design Working Tension Load of 12 kips; (3) Geo-Lock® Wall Anchors, Installed to Lengths of 15 feet, Design Working Tension Load of 12 kips Soluon: Both Geo-Lock® wall anchors and helical ebacks were used to transform the exisng simple span foundaon wall to a “ed-back” canlevered earth retaining wall. Helical ebacks were an ideal system to support the wall and extend beneath the exisng roadway without causing disrupon to traffic flow. Twenty-four (24) Model 150 (1.5-inch round corner square bar) helical ebacks with an 8”-10” double-helix lead secon were advanced through ten-inch diameter core holes using a Bobcat 323 compact excavator. Standard extensions advanced the helical ebacks to lengths on the order of 21 feet to achieve final installaon torques corresponding to ulmate capacies of at least twice the design working tension load of 12 kips (FOS ≥ 2). The core holes through the wall were filled with concrete prior to placement of the 12-inch by 28-inch wall plates. Three (3) Geo-Lock® Wall Anchors, one at each of three pilasters, were installed in foundaon wall secons not parallel to the roadway. The Geo-Lock® system was selected over helical ebacks at these locaons to prevent cung of the densely-spaced reinforcing steel. The ¾-inch anchor rods were driven through 1 1/8-inch holes drilled through the wall. The rods were advanced to lengths of approximately 15 feet and into four feet deep excavaons where they were connected to 16-inch by 26-inch earth anchor plates. The anchor rod was connected to channel steel at the inside wall face. The channel spanned from the anchor rod to a bolted connecon at the basement floor. The wall anchors and ebacks were installed approximately three feet down from the top of the wall and at a typical spacing of about five feet. All ebacks and anchors were pretensioned following installaon. Helical Tiebacks and Geo-Lock ® Wall Anchors
