00474212

Component

http://onlinepubs.trb.org...trr/1986/1072/1072-007.pdf

https://scholar.google.co...tham&publication_year=1986

Posttensioned continuous concrete bridges have shown unexpected crack patterns in the vicinity of the theoretical inflection point. In particular, box-girder-type cross sections with coupled posttensioning tendons in construction joints at the points of inflection were found to exhibit an increase in the number and width of cracks in the bottom soffit and webs of the bridge superstructure in the coupling joint vicinity. Intensive investigations attribute these cracks to highly nonlinear stress distributions with significant tensile stress content over the depth of the bridge structure due to nonuniform temperature gradients, concentrated anchorage forces, and increased prestress losses. It is shown that a major factor contributing to the tensile stress potential of the nonlinear stress distribution is a significantly reduced compressive stress state caused by the segmental construction and posttensioning sequence. The uniform state of prestress in a concentrically posttensioned concrete member shows reductions of more than half of the initial prestress in the construction and coupling joint vicinity. Combinations of this reduced compression stress field with prestress losses in the couplers or temperature gradients in the bridge deck show theoretical crack development and crack orientation similar to crack patterns encountered in coupling joint vicinities of posttensioned box-girder bridges.

Publication of this paper sponsored by Committee on General Structures. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01418776

pp 50-58

1986

Transportation Research Record

0309040663

Print

Figures (11) ; References (10) ; Tables (1)

Box girders; Bridge superstructures; Compressive strength; Concrete bridges; Construction joints; Couplers; Cracking; Deflection; Deformation curve; Joints; Nonlinear systems; Posttensioning; Prestressing; Segmental construction; Stresses; Tendons; Tension

Compressive stress; Nonlinearity; Prestress loss; Tensile stress

Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls

TRIS, TRB

Oct 31 1987 12:00AM

• APPLICATION OF EXPERT SYSTEMS IN THE DESIGN OF BRIDGES
• APPLICATION OF MICROCOMPUTERS IN BRIDGE DESIGN
• BRIDGE FORMULA DEVELOPMENT
• EVALUATION OF STEEL BRIDGES USING IN-SERVICE TESTING
• FURTHER STUDIES ON LATERAL LOAD DISTRIBUTION USING A FINITE ELEMENT METHOD
• MULTI-INCREMENT COST-ALLOCATION METHODOLOGY FOR BRIDGES
• SIMPLIFIED METHOD FOR ESTIMATING THERMAL STRESSES IN COMPOSITE BRIDGES
• TEST-TO-FAILURE OF A JACK-ARCH BRIDGE
• UMBRELLA LOADS FOR BRIDGE DESIGN