Rational and Safe Design of Concrete Transportation for Size Effect and Multi-Decade Sustainability

The goals of this proposal for a one-year continuation of support are: (1) to improve the reliability, durability and structural efficiency of infrastructure by transferring the results of previous basic research on fracture mechanics of size effects in concrete structures into: a) design practice, b) design codes; c) standardized materials testing, and d) commercial computer programs. The research will address the size effects inherent to fracture behavior and creep and shrinkage, which are important for large-span box girders of prestressed concrete bridges, as well as cable-stayed bridges, supporting piers, column footings and foundation plinths, road and airport pavements, earth-retaining walls of highways, dams, tunnel linings (which often carry highways). A large part of the effort will consist in influencing the relevant technical committees of ACI, ASTM and RILEM. There will be two thrusts: I. Size Effect on Structural Strength and Safety, and II. Creep and shrinkage with diffusion size effects, and durability, and they will be subdivided into 13 work tasks: 1) Boundary layer nonlocal model (a new idea) and its multiscale analysis; 2) Continuation and completion of experiments to calibrate the new nonlocal boundary layer model which bridges the size effect for failures at crack initiation and after large crack growth; 3) Completion of the analysis of size effect in shear-critical RC beams with stirrups. 4) Continuation of analysis of size effect in brittle torsional failure of RC beams; 5) Preparation of a chapter on size effect for ACI-446 report and fracture test recommendation; 6) Continued efforts in ASTM on adding the size effect on flexural strength to the existing ASTM-C09 standard; 7) Completion of the analysis of compression-shear failure of record-span bridge in Palau; 8) Identification of the causes of the excessive deflections of record-span bridge in Palau and their consequences for design practice and codes; 9) Extension of analysis to excessive long-time deflections of other bridges; 10) Improvement of creep and shrinkage model based on inverse analysis of measured bridge deflections; 11) Further extension and improvement of ITI database for creep and shrinkage, with about 20,000 data; 12) Continuing effort on ITI Data and Design Website for creep and shrinkage; and 13) Proposal to RILEM (a Paris-based international society) of a New Committee on RILEM Standard Recommendation on Creep and Shrinkage Prediction. The arguments for code changes will include probabilistic assessments of the failure risk with and without a change in the design code. A significant part of the efforts will be experiments on unnotched and notched beams, which should determine the proper form of nonlocal finite element modeling of size effect suitable for computer programs used in design of large sensitive structures. After winning the release of technical data (thanks to approval of a resolution proposed by Bažant at the 3rd Structural Engineers World Congress), the causes for excessive deflections and the role of size effect in failure of the record-span box girder of Palau bridge continue to be studied, in collaboration with WJE, Inc., Northbrook, IL (G. Klein). The results of analyzing the Palau catastrophe and the excessive deflections of other bridges are expected to provide potent impetus for changing the practice and codes.

• Supplemental Notes:
  • Project has been renamed from "Size Effect"

Language

• English

Project

• Status: Completed
• Funding: $522011.41
• Contract Numbers:

  610 4742000 60027740

  A222

• Sponsor Organizations:

  Infrastructure Technology Institute (ITI)

  Northwestern University
  L260 Technological Institute, 2145 Sheridan Road
  Evanston, IL  United States  60208-3109
• Principal Investigators:

  Bazant, Zdenek

• Start Date: 20080307
• Expected Completion Date: 0
• Actual Completion Date: 20120831
• Source Data: RiP Project 16775

Subject/Index Terms

• TRT Terms: Concrete structures; Creep properties; Fracture mechanics; Prestressed concrete bridges; Research projects; Shrinkage
• Uncontrolled Terms: Concrete design
• Subject Areas: Bridges and other structures; Design; Planning and Forecasting; Safety and Human Factors; I30: Materials;

Filing Info

• Accession Number: 01468449
• Record Type: Research project
• Source Agency: Infrastructure Technology Institute (ITI)
• Contract Numbers: 610 4742000 60027740, A222
• Files: UTC, RIP
• Created Date: Jan 3 2013 3:51PM