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International Concrete Abstracts Portal

Showing 1-5 of 120 Abstracts search results

Document: 

SP-340-04

Date: 

April 1, 2020

Author(s):

Michael J. Chajes, Harry W. Shenton III, Hadi T. Al-Khateeb, and Christos Aloupis

Publication:

Symposium Papers

Volume:

340

Abstract:

The maintenance and management of segmental-concrete cable-stayed bridges represents a major investment of human and financial capital. One possible approach to reducing this cost while simultaneously improving the process, is by using structural health monitoring (SHM) systems. The Delaware Department of Transportation (DelDOT), working collaboratively with the University of Delaware (UD) Center for Innovative Bridge Engineering, installed a comprehensive SHM system on the 1,749 ft (533 m) long Indian River Inlet Bridge (IRIB) during construction. The SHM system is fiber-optic based with more than 120 sensors of varying type distributed throughout the bridge. Within the first year of service, a series of three controlled diagnostic load tests were conducted utilizing the installed SHM system. The test results have been used to establish a standard set of truck passes for future tests, and the recorded response has been used to establish a baseline against which future test results can be compared. These comparisons will yield a quantitative measure of how the bridge is performing, and in combination with the more qualitative biennial inspections, will enable DelDOT to better manage this critical infrastructure asset.


Document: 

SP337

Date: 

January 30, 2020

Author(s):

ACI Committee 357 – Offshore and Marine Concrete Structures, Mohammad S. Khan

Publication:

Symposium Papers

Volume:

337

Abstract:

Offshore and marine concrete structures have not received enough attention in the recent past, at least in the United States. The complexity and safety concerns associated with these structures are such that they probably need more attention compared to many other types of concrete structures. Also, offshore and marine concrete structures are so global in nature that there is a higher need for better coordination and synchronization of design, construction, inspection, and maintenance practices in different parts of the world. A two-part session, titled “Offshore and Marine Concrete Structures: Past, Present, and Future,” was held at the Spring 2019 ACI Concrete Convention and Exposition on March 24-28 in Quebec City, Quebec, Canada. The session, sponsored by ACI Committee 357, Offshore and Marine Concrete Structures, highlighted accomplishments of the past, current state-of-the-practice, and a path for the future. This ACI Special Publication (SP) is a compilation of select papers presented at the session. The efforts of all the reviewers in assuring the quality of this publication is greatly acknowledged.


Document: 

SP-333_09

Date: 

October 1, 2019

Author(s):

Tarek Omar and Moncef L. Nehdi

Publication:

Symposium Papers

Volume:

333

Abstract:

Bridge deck condition rating systems commonly use measurements of obvious defects recorded through visual investigation. Accordingly, the condition of bridge decks is rated linguistically with inherent vagueness in the description of the deck condition. Although several advanced non-destructive testing (NDT) technologies have emerged for inspecting bridge decks, their results have yet to be incorporated in the condition rating process. The present study establishes a unique link between NDT technologies and inspector findings by developing a novel bridge deck condition rating index (BDCI). The proposed procedure captures the integrated results of infrared thermography (IRT) and ground-penetrating radar (GPR), along with visual inspection judgement deployed to evaluate a full-scale aging concrete bridge deck. The information sought to identify the parameters affecting the integration process was gathered from bridge engineers with extensive experience and intuition. The analysis process utilized the fuzzy set theory, thus overcoming the inherent scientific uncertainties and imprecision in the measurements of bridge deck subsurface defects by IRT and GPR testing along with surface defects identified through bridge inspector observations. Integrating the proposed BDCI procedure with existing bridge management systems can provide a detailed and reliable appraisal of bridge health, thus helping transportation agencies in optimizing budgets and prioritizing maintenance, repair, and rehabilitation efforts.


Document: 

SP-332_01

Date: 

July 1, 2019

Author(s):

Keith Kesner and Kevin Coll

Publication:

Symposium Papers

Volume:

332

Abstract:

Evaluation of an existing structure is a task commonly performed by licensed design professionals. An evaluation can be required by a façade inspection ordinance, as part of a due-diligence process prior to the purchase of a structure, or prior to the development of rehabilitation or repair measures. Each of these project types will have differences in the evaluation protocol and portion of the structure to be examined – but in each example, the licensed design professional is expected to provide a minimum “standard of care” to the client and to protect the public. Therefore, in developing the evaluation protocol, a critical question facing the licensed design professional is how much investigative effort is required to complete the evaluation and ensure the evaluation provides a minimum standard of care. The standard of care for an evaluation of existing structures can broadly be defined as the level of effort that a reasonable and prudent licensed design professional would be expected to provide under similar circumstances. Given the range of structure types that can be encountered and the varying levels of damage and exposure conditions, determination of the scope of evaluation can be a difficult task for a licensed design professional. The following sections examine approaches used in industry codes and ordinances to help define a minimum standard of care for the evaluation of existing structures. Industry codes and ordinances to be examined will include the ACI 562-16 Code for Assessment, Repair and Rehabilitation of Existing Structural Concrete, FHWA bridge inspection requirements and building façade inspection standards and ordinances. Based upon these documents, items to be considered in establishing a “Standard of Care” in the evaluation of existing structures will be summarized.


Document: 

SP331-01

Date: 

February 1, 2019

Author(s):

Tarek Omar and Moncef L. Nehdi

Publication:

Symposium Papers

Volume:

331

Abstract:

Bridge deck condition assessment is commonly conducted through visual inspection by bridge inspectors. Considering the colossal backlog of aging bridge structures, there is a need to develop cost-effective and innovative solutions to evaluate bridge deck conditions on regular time intervals, without interrupting traffic. This makes remote sensing technologies viable options in the field of bridge inspection. This paper explores the potential for applying infrared thermography (IRT) using unmanned aerial vehicle (UAV) to detect and quantify subsurface delaminations in concrete bridge decks. The UAV-borne thermal sensing system focuses on acquiring thermal imagery using a UAV and extracting information from the image data. Two in-service concrete bridge decks were inspected using a high resolution thermal camera mounted on a UAV. The captured images were then enhanced and stitched together using a tailored procedure to produce a mosaic view of the entire bridge deck, indicating the size and geometry of the detected delaminated areas. The results were validated by conducting hammer sounding and half-cell potential testing on the same bridge decks. The findings reveal the capability of the technology to provide measurements comparable to those derived from traditional hands-on inspection methods. Thus, it can be an excellent aid in efficient bridge maintenance and repair decision-making.


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