NCHRP 24-38 Payload Project – Development of Bridge Girder Movement Criteria for Accelerated Bridge Construction

One graduate student and one undergraduate student in addition to one post- doctoral fellow/visiting scholar.

The main objective of the payload project is to develop bridge girder movement criteria in a multi-girder superstructure of bridges for accelerated bridge construction in seismic region. To achieve the main objective, the scope of work includes, but is not limited to,

• Analyze the multi-girder superstructure of a representative real-world highway bridge in Missouri and quantify critical tolerances of the relative movement between steel or RC girders, corresponding to the strength limits of girders and the bridge deck due to lateral loads.
• Build and test under a slowly-increasing, pseudostatic load a three-girder superstructure with steel I-girders supported on a cap beam with pedestals (teeth) in between the girders in order to validate the numerically determined critical tolerant movement between steel girders.
• Built and test a three-girder superstructure with RC I-girders supported on a cap beam with pedestals (teeth) in between the girders to validate the numerically determined critical tolerant movement between RC girders.

It was observed after the 2010 Chile Earthquake that the bridges with full-depth end diaphragms always performed well. Partial-depth end diaphragms sometimes caused transverse shear block or lateral fracture failures of reinforced concrete (RC) girders. The bridges with no end diaphragms and no concrete teeth on cap beams suffered more damage. However, a number of bridges with no end diaphragms but with concrete teeth on a cap beam survived the earthquake with no significant damage except for local spalling at the concrete teeth due to the earthquake-induced pounding effect.

The above observations from the real-world bridge constructions indicated that bridge superstructures with no end diaphragms but with concrete teeth between girders are a potential alternative to the well-understood superstructures with end diaphragms. The key to make this no-diaphragm concept work is to understand how multiple girders work together during a transverse earthquake excitation or how much relative deformation they can tolerate without breaking the girders and bridge deck. The proposed payload project represents the first feasibility study towards this direction. It can greatly benefit the U.S. and beyond in terms of understanding of the seismic behavior of accelerated bridge construction connections between precast girders and thus cost effectiveness of rapid bridge constructions.

The main objective of the payload project is to develop bridge girder movement criteria in a multi-girder superstructure of bridges for accelerated bridge construction in seismic region. Specifically, a representative real-world, multi-girder highway bridge in Missouri will be analyzed and critical tolerances of the relative movement between steel or RC girders will be quantified, corresponding to the strength limits of girders and the bridge deck due to lateral loads. Two three-girder superstructures with steel I-girders and RC girders supported on a cap beam with pedestals (teeth) in between the girders will be built and tested under a slowly-increasing, pseudostatic load in order to validate the numerically determined critical tolerant movement between steel girders.

Relationship to other Research/Projects

New project

Transportation-Related Keywords

Technology Transfer Activities

A technology transfer presentation will be prepared and presented at the CIES/NUTC annual conference. A short article will also be prepared for the NUTC Newsletter. In addition, at least one technical paper will be prepared and published at archival journals or technical conferences such as the annual Transportation Research Board meeting.

Project Deliverables

Anticipated Benefits

Accelerated bridge construction (ABC) is a worldwide trend in urban areas as observed and informed by international colleagues on various post-earthquake reconnaissance trips. In the U.S., significant efforts have been devoted to understanding the seismic behavior of ABC connections between precast components. The ABC trend expects to continue in the years to come with increasing pace for implementation. Therefore, the proposed payload project can greatly benefit the U.S. and beyond.

Specifically, the numerical and experimental data and results obtained from this pilot study will allow the research team to further explore the possibility of replacing end diaphragms with concrete pedestals (teeth) in accelerated bridge constructions. Once validated and implemented, the new bridge concept with no end diaphragms but with concrete teeth will make bridge field constructions with precast components more rapidly and cost-effectively since cast-in-place diaphragms or precast diaphragm connections to girders cost time and money.

Representing a unique synergetic effort with the NCHRP project, the payload project will add significant values to the future accelerated bridge construction in the U.S., which is also an important research topic on the NCHRP agenda.

Milestones