THE BEHAVIOUR OF SOFFIT SLABS IN CONCRETE BOX GIRDER BRIDGES. SCHOOL OF ENGINEERING REPORT

The behaviour of soffit slabs in concrete box girder bridge structures was examined experimentally by building and testing a reinforced concrete U shaped girder and by carrying out a series of finite element analyses. The crack spacings and crack widths were of particular concern in the project. The U shaped girder was just under 11m long and 2.3m wide. It was constructed with the slab uppermost and it was tested so that flexure of the girder subjected the slab to flexural tension forces. The main flexural reinforcement was located close to the tension faces of the webs with an additional area of longitudinal steel being distributed through the slab of 0.41 percent of the slab area. Cracking in the concrete close to the webs was well controlled by the proximity of the main flexural tension steel. However, moving from the webs to the mid region of the slab the crack spacing and crack widths typically increased by a factor of 3 to 4. The wide cracks in this zone appear to have lead to the premature yield of the longitudinal slab reinforcement. This has implications for the fatigue resistance of cracked soffit slabs. The results of a number of finite element analyses are described. Two parameters appear to determine the crack spacing. The first of these is the strength and distribution of the reinforcement in the slab and the second depends on the geometry of the structure. (A)

• Corporate Authors:

  University of Auckland

  Department of Civil Engineering, Private Bag
  Auckland 1,   New Zealand 
• Authors:
  • Fenwick, R C
• Publication Date: 1988-1

Language

• English

Media Info

• Pagination: 72 p.
• Serial:
  • Issue Number: 445

Subject/Index Terms

• TRT Terms: Beams; Box girders; Bridges; Cracking; Fatigue (Mechanics); Finite element method; Loads; Reinforced concrete; Slabs; Stresses; Tests
• Subject Areas: Bridges and other structures;

Filing Info

• Accession Number: 00606314
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Files: ITRD, TRIS
• Created Date: Mar 31 1991 12:00AM