THE CONCRETE BRIDGE MAGAZINE

SPRING 2012

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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48 | ASPIRE , Spring 2012 S A F E T Y A N D S E R V I C E A B I L I T Y The collapse of reinforcing bar cages during constr uction causes schedule delays, cost overruns, and sometimes injuries and deaths. A series of experimental and analytical studies on the stability of bridge column cages was conducted at the University of Nevada, Reno (UNR) through a research project funded by the California Department of Transportation (Caltrans). The purpose of the study was to develop guidelines to enhance the stability of bridge reinforcing bar cages, and minimize their instability during placement or potential for full collapse. The project included designing and testing two full-scale reinforcing bar cages under lateral loads in addition to testing hundreds of tie wire connections under various types of loading conditions. The height of both test specimens was 34 ft, with an outside diameter of 3 ft 8 in. Specimen I had the longitudinal and transverse reinforcement ratios equal to 1% while Specimen II had the longitudinal and transverse reinforcement ratios equal to 2%. Internal X-type braces were used in Specimen I and square-type braces were used in Specimen II. The X-type was made of four No. 8 bars, while the square-type was made of eight No. 8 bars. The height of the braces was equal to Enhanced stability of Bridge Column reinforcing Bar Cages by Ahmad M. Itani, University of Nevada, Reno Close-up of a collapsed cage on a jobsite. All photos and drawings: University of Nevada in Reno. View of test Specimen II having a 34 ft height and 3 ft 8 in. diameter. Test Specimen II following collapse. Book_Spr12.indb 48 4/3/12 9:18 AM

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