00183801

Component

http://onlinepubs.trb.org...r/1978/665v2/665v2-029.pdf

https://scholar.google.co...goly&publication_year=1978

Longitudinally, nail-laminated timber bridge decks are used extensively in northern Canada, where the cold and dry climate discourages the activities of fungi and termites. The load-carrying capacity of these structures is dependent upon their ability to effectively distribute wheel loads among the laminates; this being a function of the friction and the holding power of the nails. Due to overloads, volumetric changes and environmental effects, the holding power tends to diminish resulting in a subsequent reduction in the load-carrying capacity of the bridge. Construction of these nail-laminated systems involves extensive labour, since thousands of nails have to be driven into hundreds of laminates. Quality control is quite difficult as it requires continuous supervision to ensure that all the nails are properly placed and driven. This report describes the application of transverse post-tensioning to an existing longitudinally nail-laminated timber deck structure in Ontario. This 3-span continuous bridge portrayed the delaminating problem, and as such, presented an appropriate test site for a post-tensioning system. Load testing was done before and after post-tensioning to determine its effects on the structure's response. An evaluation of the test results indicated that the structure's load-carrying capacity was increased by at least 100%. Transverse post-tensioning, in effect, replaces the need for nailing and hence reduces the labour required for construction. Quality control extends only to ensuring that adequate post-tensioning forces exist to provide the friction necessary for load distribution, allowing for anticipated losses due to creep. This confined deck system exhibits better resistance to the environment, as it eliminates the penetration of foreign materials between the laminations. /Author/

This paper appeared in Transportation Research Record No. 665, Bridge Engineering, Volume 2. Proceeding of a conference conducted by the Transportation Research Board, September 25-27, 1978.Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01489599

pp 236-244

1978

Transportation Research Record

Bridge Engineering Conference, 1st, 1978, St Louis, Missouri, USA

0309026970

Print

Figures (14) ; References (4) ; Tables (3)

Before and after studies; Bridge decks; Climate; Construction management; Creep; Laminated wood; Load transfer; Loads; Posttensioning; Technology; Tensioning; Timber; Trestles

Canada

Canada

Bridges and other structures; Construction; Geotechnology; Highways; Materials

TRIS, TRB

Dec 12 1978 12:00AM

• A CRITICAL EXAMINATION OF THE WAVE EQUATION
• AERODYNAMIC STABILITY OF TWO CABLE-STAYED BRIDGES
• ANALYSIS AND TESTING OF A TRAPEZOIDAL BOX GIRDER BRIDGE
• APPLICATION AND DESIGN OF PRESTRESSED DECK PANELS
• APPLICATION OF PREFABRICATED HOLLOW STEEL DECKS TO BRIDGE CONSTRUCTIONS
• CONCRETE CABLE-STAYED BRIDGES
• CONSIDERATIONS IN THE DEVELOPMENT OF AN EARLY WARNING VESSEL/BRIDGE COLLISION SYSTEM
• CURRENT PRACTICE IN DESIGN AND INSTALLATION OF DRIVEN PILES
• DEVELOPMENT OF A SIMPLIFIED METHOD OF LATERAL LOAD DISTRIBUTION FOR BRIDGE SUPERSTRUCTURES
• DYNAMIC RESPONSE OF A SINGLE TRACK RAILWAY TRUSS BRIDGE
• DYNAMIC RESPONSE OF BRIDGES
• ECONOMICAL STRUCTURES FOR LOW-VOLUME ROADS
• FATIGUE TESTS OF PRESTRESSED GIRDERS WITH BLANKETED AND DRAPED STRANDS
• INCREASING THE SEISMIC RESISTANCE OF EXISTING HIGHWAY BRIDGES
• LABORATORY AND FIELD STUDIES OF A PEDESTRIAN BRIDGE COMPOSED OF GLASS REINFORCED PLASTIC
• METHODS OF CALCULATION OF THE WIND-INDUCED RESPONSES OF SUSPENDED-SPAN BRIDGES
• MODEL STUDIES OF DOUBLE-CELL BOX GIRDER BRIDGE WITH INTERMEDIATE DIAPHRAGMS
• MULTIPLE SERVICE LEVEL BRIDGE RAILINGS--PERFORMANCE AND DESIGN CRITERIA
• PRACTICAL BRIDGE RETROFIT CONCEPTS TO REDUCE DAMAGE PRODUCED BY SEISMIC MOTIONS
• RECENT DEVELOPMENT OF CONSTRUCTION TECHNIQUES IN CONCRETE BRIDGES
• REDUCING THE RISK OF CATASTROPHIC BRIDGE FAILURES
• SEGMENTAL AND STAGE CONSTRUCTION OF PRESTRESSED CONCRETE BOX GIRDER BRIDGES
• SEGMENTAL BRIDGE CONSTRUCTION IN WESTERN EUROPE--IMPRESSIONS OF AN IRF STUDY TEAM
• STRUCTURAL PROBLEMS FOR THE MESSINA NARROWS BRIDGE
• SYSTEMS CONSTRUCTION TECHNIQUES FOR SHORT-SPAN CONCRETE BRIDGES
• TEST RESULTS FROM THE CONESTOGO RIVER BRIDGE
• THE DESIGN AND CONSTRUCTION OF THE NEW RIVER GORGE BRIDGE
• THE DEVELOPMENT OF THE ONTARIO HIGHWAY BRIDGE DESIGN CODE
• TRAFFIC LOADING OF LONG SPAN BRIDGES
• WEB STRESSES IN PRESTRESSED CONCRETE BRIDGE BEAMS HAVING DISCONTINUOUS TENDONS