Developing Prestressed Concrete Girder Cross-Sections for Longer Spans and New Materials: The pursuit of structural efficiency and reduced environmental footprint have motivated the use of ever longer spans in the world of Accelerated Bridge Construction (ABC). These trends will inevitably amplify the significance of stability considerations in the transport and handling of long-girders. It is not currently known whether existing cross-sections are sufficient, let alone optimal, for long-span applications, but field reports with long girders have shown visible lateral displacements that suggest that the girders are nearing their stability limits. This proposed work will seek to characterize long-span girder performance (strength, weight, and lateral buckling load) as a function of girder design choices, and provide insight into high-performance cross-section geometries.
Impact of Construction Eccentricity on Direct Pier-to-Pile Connections for Permanently Cased Shaft (CFST) Piles [ABC-UTC-2016-C4-UW02]: For seismic design of transportation structures, there are competing demands including: economy, strength, stiffness, inelastic deformation capacity, and seismic resilience. Prior research at the University of Washington (UW) demonstrates that concrete-filled steel tubes (CFSTs) can meet these competing demands. This proposed research builds on the prior CFST research to develop direct pier-to-pile connections specific for use in wide range of transportation systems including bridges, high speed rail (HSR), and port structures. Initially finite element analyses (FEA) were conducted to develop the connection and experimental test matrix.
3rd-Cycle Projects (2016-grant)
Design Guidelines for ABC Column-to-Drilled-Shaft Foundation Connections in High Seismic Zones [ABC-UTC-2016-C3-UW01]: The current AASHTO ABC design recommendations for shafts are based on the results of cast-in-place column behavior and a single cyclic test of a column-to-shaft subassembly. This research will use experimental data from a past study and data from a PEER-funded study to calibrate strut-and-tie and finite-element models of connections between precast columns and cast-in-place drilled shafts. The models will make be used to develop/revise design recommendations for such connections.
Economic Pier-to-Pile Connections for Permanently Cased Shaft (CFST) Piles [ABC-UTC-2016-C3-UW02]: Accelerated bridge construction (ABC) of transportation systems is important and advantageous, but most ABC techniques do not address the foundation construction. However, foundations require a large percentage of the site construction time and more than 50% of the cost. The proposed system in this research uses concrete-filled steel tubes as deep foundation elements to address many of these issues. Using the prior finite element analysis (FEA) results as a basis for the future work and specimen design and selection, the research project will investigate the connection experimentally with a focus on the impact of the pier and pile diameters, bar size, bar length (embedment) and connector design. The results will be used to determine design methods for these new connections.
2nd-Cycle Projects (2016-grant)
Development of Non-Proprietary UHPC Mix – Evaluation of the Shear Strength of UHPC[ABC-UTC-2016-C2-UW01]: Ultra-high performance concrete is a relatively recent advancement in cementitious composite materials with mechanical and durability properties far exceeding those of conventional concrete, which makes it an ideal material for bridge deck joints and other connections. While considerable information has been developed about many characteristics of UHPC, information about shear behavior is sparse. This project investigates experimentally the behavior of UHPC mixes subject to a variety of stress states, focusing on shear and including variables such as mix design and fiber content. The experimental data collected in this project will be used to develop a constitutive model for the shear behavior in UHPC, and in particular the non-proprietary UHPC materials being developed by the partner universities.
Development of ABC Course Module – Seismic Connections[ABC-UTC-2016-C2-UW02]: The goal of the proposed research is to provide a summary of the different types of seismic connection that can be achieved using ABC methods, for the benefit of future users who may not be familiar with the extensive literature on the subject. Many different connection types have been developed, so the primary effort will go into the process of categorizing them in a rational way.
Design of CFST Components and Connections for Transportation Structures: Course Module[ABC-UTC-2016-C2-UW03]: Over the past decade, significant research has been conducted on concrete-filled steel tubes (CFSTs) and their connections for use in regions of low to high seismicity. CFSTs have application to the superstructure (piers) and substructure (deep foundations). Advantages of the system included: (i) larger strength and stiffness for a given diameter in comparison with conventional RC construction, (ii) facilitation of accelerated bridge construction, (iii) improved constructability, (iv) use of environmentally-friendly (low cement) concrete for the concrete fill, and (v) improved seismic performance through damage mitigation. The course module will provide an overview of the research conducted, design expressions for the CFST components and connections, nonlinear modeling techniques, system-level response to vertical and lateral demands including earthquake and tsunami loading, and design examples.
Performance of Existing ABC Projects – Inspection Case Studies[ABC-UTC-2016-C2-UW04]: Performance of Existing ABC Projects – Inspection Case Studies: The overall goal of the proposed research is to investigate the long-term performance of projects that were constructed in the past using ABC methods, and therefore to determine whether the short-term benefits of ABC are matched by good long-term performance as well. This will be done by selecting two ABC bridges in Washington State and using them as indicators of others. Washington State was one of the first to adopt the use of precast, prestressed concrete girders, and so offers the opportunity to review a long history of that type of construction.
Tsunami Design Forces for ABC Retrofit[ABC-UTC-2016-C2-UW05]: The catastrophic damage that tsunamis cause to coastal communities is often exacerbated by the destruction of much of the transportation infrastructure. To reduce the impacts of tsunamis, it is essential that transportation agencies retrofit bridges using methods that minimize disruption to the current transportation system. This project leverages funds from the University of Washington to provide initial estimates of forces that a tsunami would impose on a bridge as the result of debris-laden flows.
1st-Cycle Projects (2016-grant)
Performance Evaluation of Structural Systems For High Speed Rail In Seismic Regions[ABC-UTC-2016-C1-UW01]: The overall goals of the proposed research are to evaluate the structural systems presently under consideration by CAHSR, develop alternative concepts and obtain feedback from CAHSR to guide their further development, and develop preliminary calculations and drawings for selected Conceptual Designs for CASHR evaluation.
New Seismic-Resisting Connections for Concrete-Filled Tube Components In High-Speed Rail Systems[ABC-UTC-2016-C1-UW02]: The overall goals of the proposed research are to investigate CFT and other column-to-pile connections through a literature review, select column-to-pile connections for study in consultation with the CAHSR technical team, investigate the seismic response and resilience of selected connections through FE analysis, and conduct limited structural analysis simulation and parametric study for a HSR bridge system.