01002750

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http://onlinepubs.trb.org...rnews238rpobridgeloads.pdf

In constructing steel bridges, contractors may decide to deploy overhang brackets, which are temporary supports placed outside the bridge's exterior girder, for the concrete forms on a bridge deck. Overhang brackets can speed construction without reducing the clearance under the structure. For this reason, the Kansas Department of Transportation (DOT) almost always uses overhang brackets for placing cantilevered slabs on bridges. Construction loads, however, can cause eccentric effects or twisting in the exterior girders that support the cantilevered portion of the slab. Although efficient for the contractor, the overhang bracket system is a challenge for the engineer, who must conduct an analysis to ensure that excessive stresses or deflections do not occur from construction loading. According to Kansas DOT specifications, a licensed professional engineer must design and stamp the formwork and the falsework drawings with a professional seal for the construction of any structure that either spans or carries traffic. To assist in this task, Kansas DOT and the University of Kansas have created a design tool, Torsional Analysis for Exterior Girder (TAEG), to aid in evaluating and designing a contractor's falsework system. The TAEG software has reduced the number of hours that engineers have to spend in analyzing the design of falsework. The accuracy of the calculations has produced bridge decks with increased levels of riding smoothness and has increased safety for contractors and for the public. According to Kansas DOT estimates, the TAEG software has saved the agency approximately $570,000 over 3 years. The software is available online.

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English

pp 38-39

2005-5

TR News

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Figures (2) ; Photos (1)

Benefits; Brackets; Cantilever bridges; Construction; Cost effectiveness; Deflection; Drawings; Falsework; Formwork; Ride quality; Safety; Software; Steel bridges; Stresses

Kansas Department of Transportation

Construction loads

Bridges and other structures; Construction; Highways; Safety and Human Factors; I53: Construction of Bridges and Retaining Walls

TRIS, TRB

Aug 1 2005 3:00PM

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