Effect of Service Temperature on Joint Removal in Steel Bridges

With the deterioration of United States (US) infrastructure systems, bridge maintenance, performance and the necessity of deck joints and bearings has gained the attention of states, municipalities, engineers, researchers, and practitioners alike. Deck joints are designed to accommodate translational and rotational movements between two adjacent bridge spans while bearings are used in bridges to transfer vertical, translational and rotational loads from the superstructure to the abutments or piers. It is commonly recognized that deck joints and bearings are costly and complicated to install (Tsiatas and Boardman 2002; Wasserman 1987). In addition to greater complexity of construction, deck joints and bearings require maintenance throughout their life cycles to remain functional and to prevent damage to the superstructure (Hawk 2003). Water seepage through deck joints can cause significant corrosion to the superstructure and substructures below (Lam et al. 2008; Loveall 1985). The American Association of State Highway and Transportation Officials (AASHTO) also recognizes this problem in the commentary section of Chapter 2.5 of the current AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications, which states: “Other than the deterioration of the concrete deck itself, the single most prevalent bridge maintenance problem is the disintegration of beam ends, bearings, pedestals, piers, and abutments due to percolation of waterborne road salts through the deck joints. Experience appears to indicate that a structurally continuous deck provides the best protection for components below the deck.” The current abundance of deck joints originated from the straightforwardness of simply supported bridge span design. During the time that simple span bridge construction was prevalent, the infrastructure system in the US rapidly grew into its current state and a large quantity of bridges and roadways were constructed. Without information available regarding the necessary maintenance and repair costs of deck joints, a multitude of bridges were constructed as multiple simple spans and separated at each pier with deck joints (Tsiatas and Boardman 2002). Recently, the use of structural analysis software programs by practicing engineers has become commonplace and, therefore, continuous span bridges can now be designed with less effort than in the past. However, a substantial amount of older bridges with numerous deck joints still exist and pose maintenance and performance challenges to state transportation agencies. Bridge retrofits to eliminate deck joints and bearings have been proposed and implemented in many cases to alleviate the substandard performance of the deck joints (Burke Jr. 1990; Tsiatas and Boardman 2002; Wasserman 1987). However, the removal of deck joints in order to improve bridge performance and increase longevity raises questions about the thermal movement bridges must be able to accommodate. In the current AASHTO LFRD Bridge Design Specifications discussion of thermal effects and discussion of joints and bearings are found in Sections 3 and 14, respectively. Multiple requirements for the performance of deck joints and bearings are listed, but the number of each should be minimized for a given bridge. The definition of setting temperature is provided and processes for estimating thermal movements of bridges are explained (AASHTO LRFD Bridge Design Specifications 2014). Current AASHTO provisions only require consideration of the total longitudinal thermal movement based on the average bridge temperature. A vertical thermal gradient is defined in Section 3, but consideration of this gradient is not required if past experience indicates that it is not necessary to maintain the functionality of the bridge. No mention of gradient in temperature is mentioned along the transverse or longitudinal axes. This over-simplified approach may result in a minimized design and analysis time since a uniform cross-sectional temperature can be assumed, but could potentially lead to inaccurate estimation of the demand resulting from the thermal loads and subsequent poor bridge performance.

Language

  • English

Project

  • Status: Active
  • Funding: $99956
  • Contract Numbers:

    DTRT13-G-UTC38

  • Sponsor Organizations:

    Research and Innovative Technology Administration

    University Transportation Centers Program
    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Kline, Robin

  • Performing Organizations:

    Colorado State University, Fort Collins

    Fort Collins, CO  United States  80523
  • Principal Investigators:

    Mahmoud, Hussam

  • Start Date: 20150625
  • Expected Completion Date: 20180731
  • Actual Completion Date: 0
  • Source Data: MPC-484

Subject/Index Terms

Filing Info

  • Accession Number: 01579601
  • Record Type: Research project
  • Source Agency: Mountain-Plains Consortium
  • Contract Numbers: DTRT13-G-UTC38
  • Files: UTC, RiP
  • Created Date: Oct 23 2015 4:29PM