Time-Dependent Prestress Loss Behavior of Girders in Missouri Bridge A7957 Compared with a U.S. Data Set of High Performance Concrete Bridge Girders

PCI Journal ◽  
2017 ◽  
Vol 62 (6) ◽  
Author(s):  
Hayder H. Alghazali ◽  
John J. Myers
Author(s):  
Yumin Yang ◽  
John J. Myers

Prestress losses have a direct impact on concrete stress development and deflection behavior of highway bridge members. A poor estimate of prestress losses can result in a structure in which allowable stresses are exceeded or camber and deflection behavior is poorly predicted, such that the serviceability of a structure may be adversely affected. This paper reports the prestress losses observed throughout fabrication, shipment, erection, and the first 2 years of service for the first high-performance superstructure concrete bridge in Missouri. The prestress losses investigated included prerelease losses, elastic shortening losses, relaxation losses, creep losses, and shrinkage losses. Results from the study were compared with eight commonly used loss estimate models for total prestress losses, including AASHTO and Prestressed Concrete Institute methods. Recommendations were proposed by the authors for the most appropriate methodology to use to predict prestress losses in high-strength concrete girders accurately.


2010 ◽  
Vol 24 (11) ◽  
pp. 2294-2311 ◽  
Author(s):  
Hazim M. Dwairi ◽  
Matthew C. Wagner ◽  
Mervyn J. Kowalsky ◽  
Paul Zia

Author(s):  
C. Sauer ◽  
F. Bagusat ◽  
M.-L. Ruiz-Ripoll ◽  
C. Roller ◽  
M. Sauer ◽  
...  

AbstractThis work aims at the characterization of a modern concrete material. For this purpose, we perform two experimental series of inverse planar plate impact (PPI) tests with the ultra-high performance concrete B4Q, using two different witness plate materials. Hugoniot data in the range of particle velocities from 180 to 840 m/s and stresses from 1.1 to 7.5 GPa is derived from both series. Within the experimental accuracy, they can be seen as one consistent data set. Moreover, we conduct corresponding numerical simulations and find a reasonably good agreement between simulated and experimentally obtained curves. From the simulated curves, we derive numerical Hugoniot results that serve as a homogenized, mean shock response of B4Q and add further consistency to the data set. Additionally, the comparison of simulated and experimentally determined results allows us to identify experimental outliers. Furthermore, we perform a parameter study which shows that a significant influence of the applied pressure dependent strength model on the derived equation of state (EOS) parameters is unlikely. In order to compare the current results to our own partially reevaluated previous work and selected recent results from literature, we use simulations to numerically extrapolate the Hugoniot results. Considering their inhomogeneous nature, a consistent picture emerges for the shock response of the discussed concrete and high-strength mortar materials. Hugoniot results from this and earlier work are presented for further comparisons. In addition, a full parameter set for B4Q, including validated EOS parameters, is provided for the application in simulations of impact and blast scenarios.


2018 ◽  
pp. 424-431
Author(s):  
Y. Malier ◽  
D. Brazillier ◽  
S. Roi

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