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Newmark Structural Laboratory Report Series (NSEL Report Series ISSN 1940-9826) >
Please use this identifier to cite this item:
http://hdl.handle.net/2142/5117
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| Title: |
Nontraditional Limitations on the Shear Capacity of Prestressed Concrete Girders |
| Authors: |
Nagle, Thomas J.
Kuchma, Daniel A. |
| Keywords: |
shear
high-strength concrete
prestressed girders
end regions
shear friction |
| Issue Date: |
2007-Dec |
| Publisher: |
Newmark Structural Engineering Laboratory. University of Illinois at Urbana-Champaign. |
| Series Name / Report no.: |
Newmark Structural Engineering Laboratory Report Series 003 |
| Abstract / Summary: |
Code based shear design provisions principally use a sectional force design procedure
in which it is assumed that plane sections remain plane. However, the shear capacity of a
member may be limited by other shear related phenomena that are not captured in codes of
practice. These nontraditional limitations on the shear capacity of a member can result from
incorrectly evaluating the shear stress that needs to be transmitted across a crack, shearcompression
failure along a web-flange interface, or insufficient capacity of longitudinal
tension reinforcement at the support.
A series of 20 shear tests were completed on ten 52-foot long and 63-inch deep
prestressed bulb-tee bridge girders cast with high-strength concrete. An extensive amount of
experimental data was gathered and advanced data analysis tools were utilized to evaluate
these nontraditional limitations on shear capacity.
It was determined that interface shear transfer resistance in high-strength concrete is
predicted well by relationships developed from tests on normal-strength concrete specimens.
It was further observed that the angle of web-shear cracking was generally steeper than the
angle of principal compressive stress as given by the AASHTO LRFD Bridge Design
Specifications. This difference in angles creates a significant shear demand on a crack that is
not accounted for in the LRFD Specifications.
A method is presented for determining if a shear-compression failure along a webflange
interface is a potential mode of failure for a prestressed bridge girder. This approach
provides a means of calculating the shear stress that must be transmitted across the interface
as a function of the geometry and loading on the member as well as a means of calculating the
shear resistance along the web-flange interface. This method can be used to guard against a
shear-compression failure by placing a limitation on the maximum shear capacity a member.
It was also determined that the requirement for longitudinal tension reinforcement near
the support included in the 4th edition of the AASHTO LRFD Bridge Design Specifications
may underestimate the demand on longitudinal tension reinforcement. Alternatively an
equilibrium based approach is presented for determining demand on longitudinal tension
reinforcement near the support. |
| URI: |
http://hdl.handle.net/2142/5117 |
| ISSN: |
1940-9826 |
| Type of Resource: |
text |
| Genre of Resource: |
technical report |
| Publication Status: |
published or submitted for publication |
| Appears in Collections: |
Newmark Structural Laboratory Report Series (NSEL Report Series ISSN 1940-9826)
|
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NSEL.Report.003.pdf (8Mb)
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NSEL report 003 |
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44 |
319 |
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