THE ANALYSIS OF RIGHT, MULTI-GIRDER, SIMPLE-SPAN BRIDGE DECKS AS EQUIVALENT TORSIONALLY-WEAK GRID SYSTEMS

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

• Supplemental Notes:
  • Report 102, 106 PP, 66 FIG, 7 REF, 1 APP
• Corporate Authors:

  Ontario Dept Hwys Jt Hwy Res Prog /Can

  ,    
• Authors:
  • Tamberg, K G
• Publication Date: 1965-1

Subject/Index Terms

• TRT Terms: Analysis; Bridge decks; Bridge members; Cartographic grids; Concrete; Diaphragms (Engineering); Distributions (Statistics); Engineering moments; Flexural strength; Formulations; Girders; Grids (Transmission lines); Length; Live loads; Matrices (Mathematics); Moments of inertia; Oversize loads; Shear strength; Shear stress; Torsion; Traffic equivalence factor; Wheel loads
• Uncontrolled Terms: Bridge spans; Overloads; Shear forces; Transverse distribution; Wheel load distribution
• Old TRIS Terms: Diaphragms; Equivalent grid system; Modified newmark method; Moment of inertia; Moments
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00208168
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 29 1994 12:00AM