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One Gifford Pinchot Drive
Madison, WI 53726-2398
Phone: (608) 231-9200
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Requested Product

Title: Improved Analytical Techniques for Historic Covered Bridges

Source: FPL RIP-4719-006

Author(s)Rammer, Douglas; Fanous, Fouad

Publication Year: 2009  View PDF »

Related Publications: view

Category: Research In Progress

Abstract: Covered bridges are complex structures containing eccentric connections, various load paths, connection uncertainty between the subassemblies (trusses and arches), and interaction between trusses and their housing (Figure 1). When these factors are combined with material variability, the conclusion that some bridges just shouldn't be standing is an understandable option. As noted in the Federal Highway Administration (FHWA) publication FHWA-HRT-04-098, Covered Bridge Manual, there are inconsistencies with the assumptions of traditional simple, static analyses of trusses that are frequently used to analyze covered bridges. For example, timber trusses tend to behave more like frames than as trusses; both axial and bending forces are carried in their members and across joints. As such, over-simplified and inaccurate analyses are often performed and overly conservative safety factors applied to account for known inaccuracies. This frequently leads to the conclusion that a historic covered bridge is inadequate to carry the required design load or to the use of inappropriate rehabilitation recommendations.

Keywords: covered bridge; analytical techniques; structural performance; connection models; modeling techniques

File size: 437 kb(s)

Date posted: 11/17/2009
Current FPL Scientist associated with this product
Rammer, Douglas R.
Research General Engineer

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