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International Concrete Abstracts Portal

Showing 1-5 of 653 Abstracts search results

Document: 

SP-341-08

Date: 

June 30, 2020

Author(s):

Ruchin Khadka, Mustafa Mashal, and Jared Cantrell

Publication:

Symposium Papers

Volume:

341

Abstract:

Recently titanium alloy bars (TiABs) have been gaining popularity in civil engineering applications. They offer good deformation capacity, better fatigue performance, high-strength-to-weight ratio, lighter weight (60% that of steel), and excellent corrosion resistance. Recently, TiABs were used in the strengthening of two bridges in Oregon to increase the shear and flexural capacities of the concrete beams. The research in this paper quantifies some common mechanical properties of TiABs using experimental investigation. This is done to explore suitability of the material for wider applications in civil infrastructure. The four types of testing conducted in accordance with ASTM standards included tension, hardness, Charpy V-Notch, and galling tests. Samples of 150 ksi (1034 MPa) high strength steel were also tested for comparison. Test results showed good performance of TiABs. Analytical models are proposed for stress-strain and toughness-temperature relationships.


Document: 

SP-342_09

Date: 

June 1, 2020

Author(s):

Denis Mitchell, Bruno Massicotte, William D. Cook, and Emre Yildiz

Publication:

Symposium Papers

Volume:

342

Abstract:

The existing Champlain Bridge is a major structure in Montreal. It contains 50 concrete spans. The 10 ft (3.1 m) deep I-girders span 172 ft (52.4 m) and are post-tensioned. Because the prestressing steel has suffered from corrosion, it was necessary to use advanced techniques to evaluate the performance of these I-girders. Detailed twodimensional non-linear finite element modelling was used to determine the responses at service load and at ultimate. Three-dimensional finite element modelling was carried out to determine the loading for the two-dimensional modelling. The serviceability checks examined if cracking would occur and the strength requirements were evaluated using predicted demand-to-capacity ratios (D/C). These analysis tools also enabled the influence of a number of strengthening techniques to be assessed. The influence of different strengthening techniques on the predicted responses of the diaphragms was also studied. The combinations of strengthening measures were found to be effective in achieving the desired serviceability and strength requirements. Keywords:


Document: 

SP-342_02

Date: 

June 1, 2020

Author(s):

Marc Savard and Jean-François Laflamme

Publication:

Symposium Papers

Volume:

342

Abstract:

Several of the first prestressed concrete segmental bridges in North America were built in Quebec, Canada. The Rivière-aux-Mulets bridge was one of them. Built in the early 1960s, this bridge experienced several disorders due to inadequate design criteria enforced at that time. Despite a structural strengthening in the late 1980s, a bridge behavior follow-up has been required to ensure reliability. The structural health monitoring program implemented to track structural disorders, along with results from modal analysis and diagnostic load tests, is presented with a focus on the instrumentation and the data analysis. A three-dimensional finite element model was developed and calibrated using the frequencies and mode shapes detected under ambient traffic conditions. Data analyses showed that the expansion bearings were frozen, causing bending of the associated piers, which generated axial forces in the deck and decompression of concrete in the area surrounding active cracks. This process enables premature failure of prestressing tendons in the vicinity of these cracks, especially those located in the top flange, which is a corrosion-friendly environment. Development of cracks and associated prestress loss caused a reduction in the bridge load-carrying capacity. Analyses of health monitoring data led to acute assessment of the overall bridge structural performance.


Document: 

SP-337_06

Date: 

January 23, 2020

Author(s):

Edward (Ted) Moffatt, Michael Thomas and Andrew Fahim

Publication:

Symposium Papers

Volume:

337

Abstract:

In 1978, the Canadian Centre of Mineral and Energy Technology (CANMET) initiated a longterm study to determine the performance of concrete in a marine environment. Between 1978 and 1994, over three hundred prisms as part of 14 different experimental phases were placed at the mid-tide level at the Treat Island exposure site. Treat Island is an outdoor exposure site operated by the U.S. Army Corps of Engineers, and lies in the Passamaquoddy Bay, part of the Bay of Fundy, near the town of Eastport in Maine. Following 25 years of exposure, the blocks were retrieved after being exposed to tidal conditions representing approximately 18,250 cycles of wetting and drying, and 2,500 cycles of freezing and thawing. This paper presents the durability performance of concrete from several phases of the CANMET study. This includes concrete incorporating various levels of supplementary cementing materials (up to 80% by mass of cementing material in some cases), with normal density and light-weight aggregate. The paper also compares output from the service-life model Life-365 with experimental chloride profile data. The results indicate the efficacy of SCMs in increasing the concrete resistance to chloride penetration. However, use of very high levels of these materials was found to render the concrete more susceptible to surface scaling. The results also showed that Life-365 model can predict chloride penetration adequately with very simple inputs.


Document: 

SP-337_03

Date: 

January 23, 2020

Author(s):

Jeremiah D. Fasl and Carl J. Larosche

Publication:

Symposium Papers

Volume:

337

Abstract:

This paper will present the challenges and unique aspects associated with increasing the capacity of one of the container wharves at Barbour’s Cut Terminal to support new Ship-to-Shore (STS) container cranes with gage lengths of 100 ft. (30 m), which was an upgrade from the previous container cranes that featured 50-ft. (15 m) gage lengths. The design criteria included achieving an additional 50 years of service life from the existing elements and new elements; therefore, the assessment results and techniques used for service life modeling will be discussed. In the new structural elements, service life modeling was used to determine the necessary concrete mixture characteristics, including use of fly ash and corrosion-resistant reinforcement, to achieve the required service life.

This paper will also discuss the design approach, including the use of springs to represent the soil-structure interaction, for determining the demands on the various components. In addition, the interaction between the new structure and existing structure and the resulting torsion will be discussed. Finally, various lessons learned from using strut-and-tie modeling, including the relative stiffness of the chord elements and need for three-dimensional modeling, will be summarized.


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