Simple made continuous bridges with steel diaphragms: tension and compression transfer mechanisms
Date
2015
Authors
Johnson, Robert I., author
Atadero, Rebecca, advisor
Chen, Suren, committee member
Clevenger, Caroline, committee member
Heyliger, Paul, committee member
Mahmoud, Hussam, committee member
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Abstract
Simple-made-continuous (SMC) steel bridges are a relatively new innovation in steel bridge design. The SMC concept has been used for quite some time in the construction of precast concrete bridges and based on current statistics, precast concrete bridge construction is outpacing steel bridge construction by a factor of two to one. The SMC concept is a viable solution for steel bridges to recover market share of the bridges constructed in the United States. The majority of SMC bridges currently in use are constructed with concrete diaphragms. This dissertation presents the results of numerical analysis and laboratory testing of an alternative simple-made-continuous connection scheme that uses steel diaphragms in lieu of concrete diaphragms. A bridge using steel diaphragms was constructed by the Colorado Department of Transportation in 2005 and the connections on this bridge serve as a basis for the research presented herein. Preliminary numerical analysis was performed by hand; this analysis discovered potential design flaws in the current bridge connection. Subsequent numerical analysis using Abaqus finite element analysis software provided results which were indecisive in regard to the flaws found in the hand analysis. The finite element analysis however, did provide valuable insight into some of the connection behavior, which was also verified with the physical test. Physical testing was subsequently performed on a full size model of the connection. The physical model consisted of double cantilever composite girders loaded at their ends with 300 kip actuators to simulate negative moments at the center connection. The physical test verified that there were design flaws in the original design. The results of analysis and physical testing provided information necessary to correct the design flaws and data required for the development of a design methodology based on the actual physical behavior of the SMC connection. Also, particular behaviors noted in the finite element analysis were corroborated with the physical test and the design methodology recognizes these behaviors. The research also compares the steel diaphragm SMC connection to concrete diaphragm connection and demonstrates that the steel diaphragm design has several desirable features. The steel diaphragm design provides for a more economical and quicker to construct steel bridge design and requires less total construction time than other SMC schemes. Additionally, since the girder ends are exposed, the girders are able to fully weather and they may be easily inspected.
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Subject
simple-made-continuous
SD-CL
steel bridges