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3
OBJECTIVE OF THE STUDY imens simulated a single beam line in a two-span bridge. This
specimen used Type III girders. In preparing this work plan,
The objective of the study, as stated by the project panel, an analysis program, RESTRAINT, was developed.
was to recommend details and specifications for the design of
durable and constructable connections that achieve structural
continuity between simple-span precast/prestressed concrete
Task 4: Prepare an Interim Report
girders. The specifications developed should be suitable for
consideration by the AASHTO Highway Subcommittee on Task 4 was a report summarizing Tasks 13.
Bridges and Structures (HSCOBS).
Task 5: Experimentally Validate
RESEARCH APPROACH the Connection Details
This project was divided into eight tasks. In Task 5, the connection details were tested in accordance
with the work plan.
Task 1: Review of Existing Data
Task 6: Develop Connection Details,
Task 1 consisted of reviewing the existing data on precast/ Recommended Specifications, Commentary,
prestressed bridges made continuous for live load. Part of this and Design Examples
task was accomplished with a literature search. The remainder
was done using surveys of state DOTs, designers, fabricators, For Task 6, the pertinent sections of the AASHTO LRFD
and contractors. The surveys focused on connection details, Specifications were reviewed and changes were recommended
materials used, constructability issues, and reported problems. based on the results of Tasks 15.
Task 2: Propose Connections To Be Tested Task 7: Seismic Issues
Using the results of Task 1, it was determined that the typi- Using available literature and some limited data from the
cal connection details could be divided into four broad cate- experiments, a discussion of seismic issues was prepared.
gories: (1) bent strand with the ends of the girders not embed-
ded in the diaphragm, (2) bent bar with the ends of the girders
not embedded in the diaphragm, (3) bent strand with the ends Task 8: Prepare the Final Report
of the girders embedded into the diaphragm, and (4) bent bar
with the ends of the girders embedded into the diaphragm. The findings of Tasks 17 are summarized in this report.
Some states used horizontal bars through the girder web for The results of the survey done under Task 1 are found in Chap-
additional strength. There was also a suggestion that additional ter 2. Chapter 2 also contains the proposed connection details
stirrups in the diaphragm, but outside of the girder bottom that were tested, details of the experimental work plan, and the
flange, would strengthen the connection. These data were used experimental results (Tasks 2, 3, and 5). Chapter 3 discusses
to propose six types of connection details for testing. the results and interpretation of data and addressed the seismic
issues (Task 7). Chapter 4 contains conclusions and recom-
mendations for future research. The RESTRAINT spreadsheet
program, developed under Task 3, is Appendix A and is avail-
Task 3: Prepare a Work Plan
able upon request from NCHRP. Appendix B provides details
A work plan was developed which centered on testing of the experimental program (Task 5). The proposed changes
six connection details for capacity and two full-size speci- to the AASHTO LRFD Specifications and Design Examples
mens. The capacity specimens consisted of two short (or (Task 6) are contained in Appendixes C and D, respectively.
stub) AASHTO Type II girders with a slab, connected to a Appendix E is the summary data from the project (in elec-
diaphragm. The connections were loaded to the anticipated tronic form) and is also available (as a diskette) upon request
design load and then subjected to fatigue. The full-size spec- from NCHRP.
