THE EFFECTS OF CONCENTRATED FORCES IN BOX GIRDERS

EFFECT DES FORCES DE PRECONTRAINTE CONCENTREES DANS LES POUTRES CAISSONS

This theoretical and experimental study concerns the anchoring of a prestressing cable in a reinforced concrete plate with free edges, thorugh the intermediary of a boss. A detailed examination of the bibliography reveals that though the problems of anchoring to the buttings of girders and of anchorages embedded in a plate have been amply studied, the same is not true of boss anchoring. This arrangement creates a dissymetry of mechanical functioning and gives the problem a three-dimensional nature. A test was performed on a concrete plate with an anchorage in its centre. The results showed that the boss appreciably reduces tractive forces behind the anchorage and improves the diffusion of the prestressing force. Three theoretical approaches are set forth. The first is an adaptation of the method developed by Schleeh in the case of an embedded anchorage. It makes it possible to calculate correctly the mean stresses in the plate. The second approach, based on the method of divisions separating the boss and the two adjacent plates, makes it possible to calculate the stresses in the plate, allowing for bending effects. The third calculation uses the technique of three-dimensional finite elements; it gives additional information on stresses in the boss. In conclusion, simple reinforcement arrangements are given, with a view to ensuring a correct structural design of the anchoring zone in the case of the place with free edges. /Author/

• Corporate Authors:

  Central Laboratory of Bridges & Highways, France

  75732 Paris,   France 
• Authors:
  • Ty, L K
• Publication Date: 1977-9

Media Info

• Features: Figures; Photos; References; Tables;
• Pagination: 115 p.

Subject/Index Terms

• TRT Terms: Anchoring; Bending; Box girders; Cable stayed bridges; Finite element method; Girders; Prestressing; Reinforced concrete; Stresses; Structural design; Structural plates
• Uncontrolled Terms: Plates
• Old TRIS Terms: Finite elements
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00168390
• Record Type: Publication
• Report/Paper Numbers: Research Rpt. LPC#68
• Files: TRIS
• Created Date: Feb 16 1978 12:00AM