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Many twin plate girder bridges have been recently rated inadequate for their current design loads... more Many twin plate girder bridges have been recently rated inadequate for their current design loads. The controlling members that determine the bridge rating is often the transverse floor beams. The current provisions assume no lateral load distribution on the floor beams. This research focused on determining how the load is actually distributed. Using the SAP2000 finite element program, different floor system models were studied. The floor beam moments found by finite element modeling were 5-20% lower than the moments predicted by the current provisions due to load distribution and the moment carried by the concrete slab. An experimental test was also run on a similar floor system and the moments on the floor beam for this test were even lower than the moments predicted using finite element modeling showing that the finite element results are conservative as well. Recommended load distribution methods for the design and rating of floor beams are presented.
Bridges that are classified as fracture critical by AASHTO require more frequent inspections than... more Bridges that are classified as fracture critical by AASHTO require more frequent inspections than other types of bridges, resulting in greater costs for their maintenance. Several historical events have shown, however, that severe damage can occur to a bridge without necessarily resulting in its collapse. A primary objective of this research project was to characterize the redundancy that exists in twin steel box-girder bridges, which are widely used in Texas and are classified as fracture critical. The main goal of the research was to develop guidelines for modeling a bridge’s behavior in the event that a fracture of a critical tension flange takes place. The research carried out under this project included laboratory testing, experimental evaluation of a full-scale box-girder bridge, and detailed structural analyses. Data gathered from the experimental testing program were used to validate nonlinear finite element models as well as simplified engineering models. Based on the resul...
Journal of Bridge Engineering, 2006
The objective of this scanning tour was to conduct a broad overview of newly developed manufactur... more The objective of this scanning tour was to conduct a broad overview of newly developed manufacturing techniques that are in use abroad for steel bridge fabrication and erection. The trip focused on the role of steel production, design, innovation, and fabrication in modern steel fabrication facilities in Japan, Italy, Germany, and the United Kingdom. The team also shared information on U.S. practice, initiatives, and research activities in these areas. As a result of the review, the team identified six high-priority areas on which the U.S. industry should focus: computer aided drawing and computer aided manufacturing; automated recording of inspection, welding variables, and geometric measurements for quality control and virtual assembly; high-performance steels and coatings; cutting and joining steel components, members, and structures; certification and contracting of steel fabrication and erection; and design innovation. Within each of these areas, the team made recommendations f...
This report documents a research investigation on connection details and bracing layouts for stab... more This report documents a research investigation on connection details and bracing layouts for stability bracing of steel bridges with skewed supports. Cross-frames and diaphragms play an important role in stabilizing steel girders, particularly during construction. The commonly used bent plate connection between skewed braces and steel girders can introduce flexibility that can have detrimental effects on the bracing behavior. An alternative detail investigated in this study is a split pipe stiffener used to connect cross-frames to girders at a skew. The split pipe stiffener allows perpendicular connections to the cross-frame connection tab, regardless of the skew angle. The split pipe provides a stiffer connection between the cross-frame and the girder. More importantly, the split pipe stiffener increases the torsional stiffness of the girder by introducing substantial warping restraint. This increases the lateral torsional buckling capacity of the girder and allows the first line o...
Journal of the Structural Division
Journal of the Structural Division
Journal of Structural Engineering, Aug 11, 2012
ABSTRACT
Journal of Bridge Engineering, 2016
Many twin plate girder bridges have been recently rated inadequate for their current design loads... more Many twin plate girder bridges have been recently rated inadequate for their current design loads. The controlling members that determine the bridge rating is often the transverse floor beams. The current provisions assume no lateral load distribution on the floor beams. This research focused on determining how the load is actually distributed. Using the SAP2000 finite element program, different floor system models were studied. The floor beam moments found by finite element modeling were 5-20% lower than the moments predicted by the current provisions due to load distribution and the moment carried by the concrete slab. An experimental test was also run on a similar floor system and the moments on the floor beam for this test were even lower than the moments predicted using finite element modeling showing that the finite element results are conservative as well. Recommended load distribution methods for the design and rating of floor beams are presented.
Bridges that are classified as fracture critical by AASHTO require more frequent inspections than... more Bridges that are classified as fracture critical by AASHTO require more frequent inspections than other types of bridges, resulting in greater costs for their maintenance. Several historical events have shown, however, that severe damage can occur to a bridge without necessarily resulting in its collapse. A primary objective of this research project was to characterize the redundancy that exists in twin steel box-girder bridges, which are widely used in Texas and are classified as fracture critical. The main goal of the research was to develop guidelines for modeling a bridge’s behavior in the event that a fracture of a critical tension flange takes place. The research carried out under this project included laboratory testing, experimental evaluation of a full-scale box-girder bridge, and detailed structural analyses. Data gathered from the experimental testing program were used to validate nonlinear finite element models as well as simplified engineering models. Based on the resul...
Journal of Bridge Engineering, 2006
The objective of this scanning tour was to conduct a broad overview of newly developed manufactur... more The objective of this scanning tour was to conduct a broad overview of newly developed manufacturing techniques that are in use abroad for steel bridge fabrication and erection. The trip focused on the role of steel production, design, innovation, and fabrication in modern steel fabrication facilities in Japan, Italy, Germany, and the United Kingdom. The team also shared information on U.S. practice, initiatives, and research activities in these areas. As a result of the review, the team identified six high-priority areas on which the U.S. industry should focus: computer aided drawing and computer aided manufacturing; automated recording of inspection, welding variables, and geometric measurements for quality control and virtual assembly; high-performance steels and coatings; cutting and joining steel components, members, and structures; certification and contracting of steel fabrication and erection; and design innovation. Within each of these areas, the team made recommendations f...
This report documents a research investigation on connection details and bracing layouts for stab... more This report documents a research investigation on connection details and bracing layouts for stability bracing of steel bridges with skewed supports. Cross-frames and diaphragms play an important role in stabilizing steel girders, particularly during construction. The commonly used bent plate connection between skewed braces and steel girders can introduce flexibility that can have detrimental effects on the bracing behavior. An alternative detail investigated in this study is a split pipe stiffener used to connect cross-frames to girders at a skew. The split pipe stiffener allows perpendicular connections to the cross-frame connection tab, regardless of the skew angle. The split pipe provides a stiffer connection between the cross-frame and the girder. More importantly, the split pipe stiffener increases the torsional stiffness of the girder by introducing substantial warping restraint. This increases the lateral torsional buckling capacity of the girder and allows the first line o...
Journal of the Structural Division
Journal of the Structural Division
Journal of Structural Engineering, Aug 11, 2012
ABSTRACT
Journal of Bridge Engineering, 2016