Field Investigation of Spread Slab Beam Bridge Systems and Development of Design Parameters
April 6, 2016
Field Investigation of Spread Slab Beam Bridge Systems and Development of Design Parameters
Abstract: The Texas Department of Transportation (TxDOT) uses precast prestressed concrete slab beam bridges in a side-by-side configuration as an alternative to prestressed concrete I-girder bridges for short span bridges in low clearance areas. In order to reduce costs, a new bridge type called a spread slab beam bridge was recently developed using the same concept as spread box beam bridges in which the beams are spaced apart. The research team evaluated spread slab beam bridges in terms of design, constructability, and performance. Forty-four bridge geometries were designed using standard TxDOT slab beam types to determine the feasible design space. One of the most challenging geometries with widely spaced slab beams was constructed at full-scale in the field. The bridge was tested under static and dynamic vehicular loads to evaluate constructability and structural performance. Another in-service spread slab beam bridge was also instrumented and tested to obtain important insight on the performance of the new bridge system with more closely spaced beams. The load distribution behavior was investigated in the field testing and the measured data of both bridges was utilized to validate computational modeling techniques for this new bridge system.
Based on the research findings, it is concluded that spread slab beam systems that utilize precast concrete panels with a cast-in-place concrete deck provide a viable construction method for short-span bridges. For both tested bridges, the desired performance was achieved for in-service loading. During field testing the beam live load deflections were within the design limits and no significant cracking or reduction in the overall stiffness of the bridge was observed. Experimental load distribution factors (LDFs) were evaluated using alignments that provided the most adverse loading cases. In addition, LDFs for design were developed based on computational models of spread slab beams with varying geometric parameters.
Bio: Dr. Mary Beth Hueste is a Professor in the Zachry Department of Civil Engineering at Texas A&M University. She joined Texas A&M University in 1998 where she is a member of the structural engineering faculty. Dr. Hueste is the Major Highway Structures Program Manager within the Texas A&M Transportation Institute. She is a Fellow of the American Concrete Institute (ACI) and Chair of ACI-ASCE Committee 352 (Joint and Connections in Monolithic Concrete Structures). Dr. Hueste conducts research focused on earthquake resistant design of reinforced concrete structures, performance-based seismic design, design and evaluation of prestressed concrete bridge structures, and assessment of aging and historic infrastructure. She has authored or co-authored over 70 technical papers and reports. She is a registered professional engineer in Kansas and Texas and holds a BS from North Dakota State University, a MS from the University of Kansas, and a PhD from the University of Michigan; all in Civil Engineering.
