EFFECTS OF BANDED POST-TENSIONING IN A PRESTRESSED CONCRETE FLAT SLAB. FINAL REPORT

A new class of flat slab concrete bridges employs bidirectional post-tensioning. While longitudinal post-tensioning is uniform, transverse tendons are concentrated in the vicinity of column lines to act as bentcap-like supports. For multispan structures, transverse post-tensioning is limited to a series of narrow banded regions. This report, first in a series, documents displacement, strain, stress, and punch-through shear capacity of a 3/10ths scale model of a column and slab region of a prototype bridge. Concomitant efforts are underway on a large two-span laboratory bridge model, a field study of a full-size bridge, and a numerical simulation package. The current study investigates degree of validity of a design procedure for a column region of a prototype bridge. Construction, instrumentation, testing, and numerical simulation are described for the concrete model slab. A loading schedule enables stress distribution determination for a variety of tendon and load patterns. The number of stressed tendons varies from one to nine. Results of a large number of transducer readings and finite element simulations are presented via fringe plots, tables, and graphs. Finally, the slab is loaded by a specially fabricated load frame and the circular support column so as to impose punch-through shear failure. A brittle failure at 207 kips (923 kN) is followed by reserve capacity at 111 kips (496 kN) which collapsed the slab. Shear formulas recommended by the American Association of State Highway and Transportation Officials, American Concrete Institute, and other researchers are compared with experimental failure and reserve capacity loads.

• Supplemental Notes:
  • Research study title: Evaluation of Factors Affecting Slabs Due to Localized Post-Tension Forces.
• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 1600 E Lamar Boulevard
  Arlington, TX  United States  76011

  Texas State Department of Highways & Public Transportation

  Transportation Planning Division, P.O. Box 5051
  Austin, TX  United States  78763

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Roschke, P N
  • INOUE, M
• Publication Date: 1990-6

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 134 p.

Subject/Index Terms

• TRT Terms: Bridges; Brittleness; Columns; Concrete; Deformation curve; Design methods; Dislocation (Geology); Failure; Finite element method; Posttensioning; Prestressed concrete; Puncture resistance; Scale models; Shear properties; Shear stress; Slabs; Strain (Mechanics); Stresses; Tensioning; Validity
• Uncontrolled Terms: Punching shear; Shear capacity
• Old TRIS Terms: Brittle failures; Longitudinal tensioning; Shear failures; Strains; Transverse tensioning
• Subject Areas: Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 00616397
• Record Type: Publication
• Report/Paper Numbers: FHWA/TX-90/1182-1, Res Rept 1182-1, TTI: 2-5-88-1182
• Contract Numbers: Study 2-5-88-1182
• Files: TRIS, USDOT, STATEDOT
• Created Date: Oct 31 1991 12:00AM