Title page for ETD etd-10122011-150234


Type of Document Master's Thesis
Author Passarelli, Garrett J
Author's Email Address passarg@vt.ed
URN etd-10122011-150234
Title A Feasiblity Study on the Fatigue Performance of Laser Beam Welds and Hybrid-Laser Arc Welds Used in an Innovative Modular Steel Sandwich Panel Bridge Deck SyStem
Degree Master of Science
Department Civil Engineering
Advisory Committee
Advisor Name Title
Wright, William J. Committee Chair
Moen, Cristopher D. Committee Co-Chair
Cousins, Thomas E. Committee Member
Keywords
  • Bridge Decks
  • Fatigue Resistance
  • Finite Element Analysis
  • Finite Element
  • Sandwich Panel
  • Laser Weld
  • LBW
  • HLAW
Date of Defense 2011-09-28
Availability restricted
Abstract
This research investigation explores the feasibility of implementing a laser welded

sandwich steel panel bridge deck system as a viable alternative to standardized reinforced

concrete bridge decks. Generally used in naval ship building applications, steel sandwich

panels possess attractive characteristics towards the integration with bridge infrastructure such

as service life in excess of 100 plus years, dead load reduction, rapid construction, decreased

closure time, and automated mass production. The lack of fatigue data for the laser “stake”

welds used to create the enclosed sandwich panel geometry raised concerns with respect to

fatigue life. The primary focus of this study was to determine whether or not infinite fatigue life

was possible. Two different laser welding technologies were investigated, Laser Beam

Welding (LBW) and Hybrid-Laser Arc Welding (HLAW). Test specimens were fabricated and

tested in order to examine fatigue resistance based on a localized load effect between adjacent

core stiffeners. Finite element models were used to obtain the stress range for each individual

test due to complex geometry and partially restrained boundary conditions. In order to assess

the fatigue performance of the overall deck system, additional finite element models were

created to study the local and global behavior of different sandwich panel configurations. As a

whole the investigation yielded promising results. Infinite fatigue life is achievable due to

outstanding fatigue performance. The HLAW stake welds demonstrated superior fatigue

resistance in comparison to the LBW process. Localized load effects can be minimized

through the modification of different panel parameters. Pushing forward, full scale testing is

essential to the future employment of this innovative bridge deck system.

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