International Concrete Abstracts Portal

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International Concrete Abstracts Portal

Showing 1-5 of 461 Abstracts search results

Document:

SP-323_05

Author(s):

Carlos V. Aguilar, David V. Jáuregui, Brad D. Weldon and Craig M. Newtson

Publication:

Special Publication

Volume:

323

Issue:

  

Abstract:

Off-system concrete bridges with no design plans are currently a concern in New Mexico as many exist throughout the State. Load rating these bridges is problematic since the design documentation is limited or missing, thus creating uncertainties regarding the safe load limits. Two prestressed concrete bridges, a double T-beam and box beam bridge, were evaluated using advanced analyses and experimental methods (including load testing and rebar scanning). Both bridges have damaged and/or missing shear keys between the adjacent beams and thus, the load distribution path was uncertain. The bridges were evaluated based on the following procedures: estimating the material properties from past specifications and amount of prestressing steel via Magnel diagrams; verifying the steel estimate with a rebar scanner; load testing based on strain measurements; and rating the bridges using the load test results. Rating factors were determined for legal loads based on serviceability (i.e., concrete cracking) and strength (i.e., shear or flexural capacity). The serviceability ratings from load testing and strength ratings from analytical software were compared to determine the final load ratings and need for posting the bridges.

Date:

May 1, 2018

  


Document:

SP-323_03

Author(s):

Anna Halicka, Dick A. Hordijk, Eva O.L. Lantsoght

Publication:

Special Publication

Volume:

323

Issue:

  

Abstract:

Nowadays, finite element analyses provide information about the performance of a structure, but they are more or less simplified. Therefore, load tests are the only way to find the “real” behavior of an existing bridge subjected to the rating process. In this paper, the state-of-the-art concerning load tests of concrete road bridges is presented, and the problems of the execution of such tests are specified. It is pointed out that only load tests accompanied with current finite element analyses may result in a proper assessment of the level of safety of the bridge. The authors’ procedure of complex assessment of such bridges combines in-situ examination of the structure, load testing, and finite element modeling. The paper discusses the following topics: aims and fundamentals of static diagnostic and proof load tests; the load application method according to different codes and specifications; the basis for proper assessment of the target load: reliability index, partial factors approach, global rating factor approach; establishing the load allowable on the bridge, based on the applied proof load; and the proposed procedure of assessment of existing concrete road bridges by load testing.

Date:

May 1, 2018

  


Document:

CI4005Obla

Author(s):

Karthik H. Obla, Daniel J. Gancarz, William R. (Rusty) Owings III, Fouad H. Yazbeck, and David G. Tepke

Publication:

Concrete International

Volume:

40

Issue:

5

Abstract:

Performance-based specifications that define explicit durability goals can be successfully used on diverse project types. This article summarizes four examples of such projects (pavement, bridge, development, and column repair) that were presented at a session, Case Studies of Performance-Based Specifications, at The ACI Concrete Convention and Exposition – Spring 2017 in Detroit, MI.

Date:

May 1, 2018

DOI:

  


Document:

CI4002Bass

Author(s):

Randall P. Bass and Gary Horninger

Publication:

Concrete International

Volume:

40

Issue:

2

Abstract:

Key features of roller-compacted concrete (RCC) dams are highlighted, using various dam types as examples. Topics include lift interfaces, facing systems, spillways, intakes and outlets, internal galleries, and joints. Test sections are recommended for training and to demonstrate that the systems, methods, and equipment proposed for a project will meet project specifications.

Date:

February 1, 2018

DOI:

  


Document:

SP-320_38

Author(s):

R. Douglas Hooton, Lawrence Sutter, and Mary Christiansen

Publication:

Special Publication

Volume:

320

Issue:

  

Abstract:

There has been a proliferation of research and development activity focused on chemically activated binder technologies and other alternative cements for use in concrete. Some activated binder technologies have been used successfully in construction or in manufacture of building products. However, a major barrier to adoption of such new materials is the lack of appropriate test methods and specifications, often precluding their use in structural applications since they are not covered by building codes. Some existing test methods may be suspect for evaluation of new cementing materials because they often do not relate well to field performance for portland cement concrete. However, engineers have experience, familiarity and a comfort level with using portland cement concrete. In addition to raising specific areas of concern with existing test methods, alternative approaches to adapting existing test methods or development of new tests specific to evaluation of chemically activated binders and alternative cements are discussed.

Date:

August 1, 2017

  


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