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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 13 Abstracts search results
Document:
SP88
Date:
November 1, 1985
Author(s):
Editor: Tony C. Liu
Publication:
Symposium Papers
Volume:
88
Abstract:
SP-88 This volume covers a wide range of subjects of strength evaluation of existing concrete bridge structures: including condition survey, analytical investigation methods such as finite element analysis and modified compression field theory, in situ load testing, laboratory modeling and testing, deflection measurement methods, remote sensing techniques, and strategy for rating older concrete bridges. Case histories are also included.
DOI:
10.14359/14045
SP88-12
James T. Kunz and Jerry W. Eales
Thermal infrared and ground penetrating radar remote sensing technologies have been applied to the non-destructive evaluation of existing concrete bridge decks. Delaminations in a concrete bridge deck can be identified rapidly and effectively with the use of a thermal infrared scanner. This technique pro-vides an efficient and economical alternative to traditional sounding techniques utilized to identify delamination. The thermal infrared technique can be used to identify delaminations on exposed concrete bridge decks and decks overlaid with asphalt. Ground penetrating radar can be utilized to rapidly identify and evaluate various bridge deck conditions. The equipment can be used to measure deck thickness, identify thin, weakened areas and determine the position of reinforcing steel within the deck.
10.14359/6268
SP88-11
Frank F. Liou
The Nelson Street Bridge in downtown Atlanta, Georgia is a ten-span continuous concerete arch bridge. Designed for carrying electric street cars, it was built in 1906. The bridge is present-ly carrying local street traffic over active tracks of the Southern Railway System and automobile parking areas. Strength evaluation procedures contrasted the latest design speci-fications and modern analysis techniques with the original design approach in every aspect. A slab-grid model was used for analyzing lateral wheel load distribution on a multiple arch and slab system. The distribution factors were then compared with those recommended by current AASHTO specifications for concrete slabs on concrete T-Beams. Arch geometry was accurately simulated, and moving axle loads were generated in a computer program. Force envelopes were produced for arch sections spaced from one foot to six feet along the arch, using critical loading positions. Sections were then checked for combined compression and bending. This approach is particularly effective when the spacing of arches is unequal and span lengths vary. Concrete cores were taken from the bridge and tested for compres-sive strength and chemical properties. Test results were satisfac-tory when compared with recommendations in the AASHTO Manual for Bridge Rating and turn-of-the-century books on concrete design. Sound arch sections from original contract plans, and existing sec-tions with concrete and steel losses determined by field inspection were used for evaluating section capacities.
10.14359/6267
SP88-10
Gary J. Klein and Predrag L. Popovic
Because prior AASHTO design codes permitted a much greater shear stress in concrete than allowed by current codes, the shear strength of existing bridges may be questioned. This paper offers an approach to shear strength assessment of bridge beams. The condition of the existing structure, theoretical strength based on recent research, and the unique characteristics of older concrete bridges are considered. Field investigation and rating methods are discussed, and a case study is presented.
10.14359/6266
SP88-09
F. E. Fagundo and J. M. Richardson
Precast panel deck bridges have been in use for many years. Although some cracking is inherent in this structural system, recent concern has been expressed because of the greater degree of cracking exhibited on the surface of some decks compared to conventional cast-in-place bridge decks. Full scale structural testing was initiated to estimate the strength and evaluate the performance of the deck panel system. In this program two deck panel bridges, each with different panel support details, and a conventional cast-in-place deck bridge were tested. Results showed that the deck panel system did not act as a continuous slab over the girders as is usually assumed for design. The conventional cast-in-place deck bridge did develop continuity. The effect is to increase the maximum positive moments in the slab but not to a degree as to render the bridges unsafe.
10.14359/6265
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