Precast, prestressed concrete panels (PCPs) have been widely used in Texas as
stay-in-place formwork in bridge deck construction. Although PCPs are widely popular
and extensively used, Texas is experiencing problems with collinear cracks (cracks along
the strands) in panels. One reason for the formation of collinear cracks is thought to be
the required level of initial prestress. Currently, PCPs are designed assuming a 45-ksi,
lump-sum prestress loss. If the prestress losses are demonstrated to be lower than this
value, this could justify the use of a lower initial prestress, probably resulting in fewer
collinear cracks. For this purpose, 20 precast, prestressed panels were cast at two
different plants. Half of those 20 panels were fabricated with the current TxDOT-required
prestress of 16.1 kips per strand, and the other half were fabricated with a lower prestress
of 14.4 kips per strand based on initially observed prestress losses of 25 ksi or less.
Thirteen of those panels were instrumented with strain gages and monitored over their
life time. Observed losses stabilized after five months, and are found to be about 24.4 ksi.
Even with the reduced initial prestress, the remaining prestress in all panels exceeds the
value now assumed by TxDOT for design. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/ETD-UT-2012-08-6180 |
| Date | 29 October 2012 |
| Creators | Azimov, Umid |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Type | thesis |
| Format | application/pdf |
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