United States Department of Transportation
ROSA P serves as an archival repository of USDOT-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by USDOT or funded partners.
As a repository, ROSA P retains documents in their original published format to ensure public access to scientific information.
i
Improving the accuracy of camber predictions for precast pretensioned concrete beams.
-
2015-07-01
-
[PDF-4.73 MB]
Details:
-
Creators:
-
Corporate Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
Corporate Publisher:
-
Abstract:The discrepancies between the designed and measured camber of precast pretensioned concrete beams (PPCBs) observed by the
Iowa DOT have created challenges in the field during bridge construction, causing construction delays and additional costs. This
study was undertaken to systematically identify the potential sources of discrepancies between the designed and measured camber
from release to time of erection and improve the accuracy of camber estimations in order to minimize the associated problems in
the field.
To successfully accomplish the project objectives, engineering properties, including creep and shrinkage, of three normal
concrete and four high-performance concrete mix designs were characterized. In parallel, another task focused on identifying the
instantaneous camber and the variables affecting the instantaneous camber and evaluated the corresponding impact of this factor
using more than 100 PPCBs. Using a combination of finite element analyses and the time-step method, the long-term camber was
estimated for 66 PPCBs, with due consideration given to creep and shrinkage of concrete, changes in support location and
prestress force, and the thermal effects.
Utilizing the outcomes of the project, suitable long-term camber multipliers were developed that account for the time-dependent
behavior, including the thermal effects. It is shown that by using the recommended practice for the camber measurements
together with the proposed multipliers, the accuracy of camber prediction will be greatly improved. Consequently, it is expected
that future bridge projects in Iowa can minimize construction challenges resulting from large discrepancies between the designed
and actual camber of PPCBs during construction.
-
Format:
-
Alternate URL:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type:
