EXTERNALLY PRESTRESSED MEMBERS: EVALUATION OF SECOND-ORDER EFFECTS

The deterioration of bridges due to increased traffic loading, progressive structural aging, and reinforcement corrosion from severe weathering conditions has become a major problem around the world. External prestressing is considered one of the most powerful techniques used for strengthening or rehabilitation of existing structures and has grown to occupy a significant share of the construction market. This paper presents the results of an analytical investigation of the strength and structural behavior of concrete members prestressed with external tendons. The behavior at both the serviceability and ultimate limit states is evaluated. A nonlinear analysis model, based on the incremental deformation method, is developed to predict the entire response of concrete members originally designed with or strengthened by external prestressing. The proposed analysis reproduced experimental results of deflection and tendon stress responses with remarkable accuracy. A parametric study was undertaken to evaluate the behavior of concrete beams either designed using external prestressing or strengthened by it. The analytical results demonstrated that the second-order effect, associated with the progressive change in eccentricity of the tendons with increasing member deformation, is the main factor that distinguishes the behavior of external tendons from an internal unbonded tendon system. Because of this effect, undeviated external tendons mobilized lower nominal flexural resistance and inelastic deflections than did deviated tendons. When used for strengthening concrete flexural members, providing a moderate amount of external prestressing steel leads to significant deflection recovery, some reduction in the live load deflection, and a substantial increase in the yield load and ultimate flexural capacity of the members.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/07339445
• Corporate Authors:

  American Society of Civil Engineers

  1801 Alexander Bell Drive
  Reston, VA  United States  20191-4400
• Authors:
  • Harajli, M
  • Khairallah, N
  • Nassif, H
• Publication Date: 1999-10

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 1151-61
• Serial:
  • Journal of Structural Engineering
  • Volume: 125
  • Issue Number: 10
  • Publisher: American Society of Civil Engineers
  • ISSN: 0733-9445
  • Serial URL: http://ascelibrary.org/loi/jsendh

Subject/Index Terms

• TRT Terms: Beams; Bridges; Concrete structures; Deflection; Deformation; Eccentricity; Flexural strength; Highway bridges; Mathematical models; Prestressed concrete bridges; Prestressing; Rehabilitation; Reinforcing steel; Stress (Physiology); Structural analysis; Structural members; Tendons; Ultimate load design
• Non-Preferred Terms: Serviceability
• Subject Areas: Bridges and other structures; Design; Highways; Maintenance and Preservation; I24: Design of Bridges and Retaining Walls; I60: Maintenance;

Filing Info

• Accession Number: 00770127
• Record Type: Publication
• Contract Numbers: B-9135, CMS-9625070, CMS 9712761
• Files: TRIS
• Created Date: Oct 8 1999 12:00AM