Frictional Loss of Prestress Caused by Locally Deflected Tendons in Prestressed Concrete Girder Bridges

2015 ◽  
Vol 1119 ◽  
pp. 716-720 ◽  
Author(s):  
Kyung Joon Shin ◽  
Yun Yong Kim ◽  
Hwan Woo Lee

Prestressed concrete girder bridges are one of the most widely used bridges in the world because of their excellent construction feasibility, economic efficiency, serviceability, and safety. In certain situations, however, the prestressing tendon is supposed to be bent locally, and this leads to the loss of prestress force. This kind of prestress loss is not considered in the design and construction processes. This study shows that prestress loss occurs at the locally bent tendon, and that a 2% maximum of prestress loss occurs at the locally bent tendon, due to eccentricity.

2014 ◽  
Vol 513-517 ◽  
pp. 2599-2602 ◽  
Author(s):  
Kyung Joon Shin ◽  
Yun Yong Kim ◽  
Hwan Woo Lee

Bending of a prestressing tendon by construction error or the radius of curvature at the continuous joint of PSC girders cannot be avoided. However, this kind of prestress loss is not considered in design and construction processes. This study proves that prestress loss occurs at the continuous joint due to local bending of the tendon which is induced by construction error or the radius of curvature. The result shows that a maximum 3 % of prestress loss occurs at the continuous joint for a single tendon.


2020 ◽  
Vol 19 (3) ◽  
pp. 103-115
Author(s):  
Andrzej S. Nowak ◽  
Olga Iatsko

There has been a considerable progress in the reliability-based code development procedures. The load and resistance factors in the AASHTO bridge design code were determined using the statistical parameters from the 1970's  and early 1980’s. Load and resistance factors were determined by first fixing the load factors and then calculating resistance factors. Load factors were selected so that the factored load corresponds to two standard deviations from the mean value and the resistance factors were calculated so that the reliability index is close to the target value. However, from the theoretical point of view, the load and resistance factors are to be determined as coordinates of the so-called “design point” that corresponds to less than two standard deviations from the mean. Therefore, the optimum load and resistance factors are about 10% lower than what is in the AASHTO LRFD Code. The objective of this paper is to revisit the original calibration and recalculate the load and resistance factors as coordinates of the “design point” for prestressed concrete girder bridges. The recommended new load and resistance factors provide a consistent reliability and a rational safety margin.


2002 ◽  
Vol 1 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Samer Barakat . ◽  
Ali Salem Al Harthy . ◽  
Aouf R. Thamer .

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