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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 61 Abstracts search results
Document:
SP94-47
Date:
July 1, 1987
Author(s):
T. Hara and T. Otsuka
Publication:
Symposium Papers
Volume:
94
Abstract:
Tests for four circular segmented tunnel linings are described. Two single-ring specimens had the conventional flat joint and the tongue-and-groove joints at the key segment. The three-ring specimens used a staggered arrangement and had circumferential joints with and without tongue-and-groove configurations. The load was applied from the top and the side wall on the single-ring specimens. The measurements of overall deformation, joint slip at the key segment, and joint opening were used in studies of waterproofing joints of several linings. The type of joint configurations that has been proven satisfactory is the key segment with the tongue-and-groove for the longitudinal joint. This selection is based largely on economic factors. Documented field cases observed in the underground excavations carried out for the electric utility tunnels in the urban areas were presented to investigate the applicable watertightening joint of segmented linings.
DOI:
10.14359/3364
SP94-41
R. Price
The Texas State Department of Highways and Public Transportation has developed through laboratory testing a material specification for elastomeric concrete and for use as expansion joint nosing material. The elastomer is specified by physical properties such as tensile stress, elongation, bond strength, and compressive resilience. Physical properties are determined after short-term curing and long-term oven aging. To date, approximately 4000 ft (1219 m) of joint has been placed according to this specification. Although the oldest installation is only one year old, the performance of the joints has been excellent. An experimental installation, scheduled for August 1986, includes four different elastomeric concretes in approximately 1500 ft (457 m) of joint. The performance of these joints will be correlated with physical property testing and used to improve the existing specification.
10.14359/3408
SP94-42
M. Bujtas
A concept of pot bearing rotation and its relation to vertical load, rotating moment, and eccentricity are examined. At certain low load and rotating combinations, uniform piston contact with the elastomer or the upper element will not occur, resulting in an uneven load transfer and increased eccentricity. Factors that may be traced to this phenomenon are presented. The rotating moment expression used contains an empiric "alpha factor" variable with three known values. Derived from early rotation tests, this "alpha" is based on the diameter-to-height (D/h) ratio of the confined elastomer. An expression for "alpha" was formulated to provide unique factors for each case. Eccentricity and eccentric neutral stress points were computed in all cases. Critical loads are indicated where piston contact loss is possible. This occurs when the eccentricity is less than the eccentric neutral stress point and at the maximum kern of the inner pot section. Piston separation here is likely, due either to the extreme eccentricity or the confined elastomer's resistance to deform at low pressures. Its importance should not be overlooked as future studies may provide substantiation. However, in assuming static equilibrium, complete piston contact is assured so long as the eccentricity remains within the kern of the pot section.
10.14359/3413
SP94-44
S. Pabst
Elastomeric concrete, when used as a transition medium in the traffic impact area, is a simplistic low-profile concept that vulcanizes permanently to the structural concrete of the bridge deck. This procedure has proven effective in waterproofing the problematic expansion joint areas while providing a unique impact-attenuating transition solution.
10.14359/3419
SP94-46
C. Redfield and C. Seim
What does an engineer do when a defective pot bearing needs replacing? This particular situation was encountered on two recent construction jobs. Several of the pot bearings on the Cline Avenue Project in East Chicago, Ind., needed to be replaced because the elastomer was extruding from the pot. On the I-285 project in Atlanta, Ga., six pot bearings were misaligned and had to be readjusted. The superstructure on both projects was cast in place prestressed concrete box girders. The performance of replacing the pot bearings required designing, fabricating, and installing temporary steel frames, performing special jacking operations, and removing and replacing the pot bearings. This paper describes the operation for both projects in hopes that the solutions illustrated herein may be used by others to help solve similar problems.
10.14359/3425
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