FRACTURE ANALYSIS OF CRACKING IN CONCRETE BEAMS

An energy balance criterion, based on fracture mechanics concepts, is proposed for predicting the loads at which concrete members develop rapidly propagating cracks. After an initial period during which microcracks increase slowly in length and extent over a critical region of the member, an unstable running crack develops when the rate of energy released by continuing microcrack growth exceeds the energy inputed to the system. The shape of the growing microcrack zone is determined by the stress intensity factors for the extremities of the principal axes of that zone. A critical strain energy release rate, G sub c, is determined from direct tensile data and its appropriateness verified by showing that strength and size effects are correctly predicted for modulus of rupture specimens. Diagonal tension cracking load expressions for reinforced concrete beams are developed using the G sub c value and energy criterion. Those expressions correctly predict the effects estabilished from tests of the moment of shear ratio, reinforcement ratio, type of loading, and size of member. /Author/

• Corporate Authors:

  American Society of Civil Engineers

  345 East 47th Street
  New York, NY  United States  10017-2398
• Authors:
  • Hawkins, N M
  • Wyss, A N
  • Mattock, A H
• Publication Date: 1977-5

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 1015-30
• Serial:
  • Journal of the Structural Division
  • Volume: 103
  • Issue Number: ST5
  • Publisher: American Society of Civil Engineers

Subject/Index Terms

• TRT Terms: Beams; Cracking; Energy balance; Forecasting; Fracture mechanics; Loads; Microcracking; Modulus of rupture; Reinforced concrete; Shear strength; Strain (Mechanics); Structural analysis; Testing
• Uncontrolled Terms: Crack propagation; Fracture; Microcracks; Reinforced concrete beams
• Old TRIS Terms: Strains
• Subject Areas: Bridges and other structures; Energy; Highways;

Filing Info

• Accession Number: 00165324
• Record Type: Publication
• Report/Paper Numbers: ASCE 12921 Proceeding
• Files: TRIS
• Created Date: Mar 14 1978 12:00AM