Implication of increased live loads on the design of precast concrete bridge girders

PCI Journal ◽  
2012 ◽  
Vol 57 (4) ◽  
pp. 78-95 ◽  
Author(s):  
Nagib Gerges ◽  
Antoine N. Gergess
Keyword(s):  
Precast Concrete ◽  
Bridge Girders ◽  
Concrete Bridge ◽  
Live Loads

Saint-Venant torsion constant of modern precast concrete bridge girders

PCI Journal ◽  
2021 ◽  
Vol 66 (3) ◽  
pp. 23-31
Author(s):  
Richard Brice ◽  
Richard Pickings
Keyword(s):  
Prestressed Concrete ◽  
High Performance Concrete ◽  
Precast Concrete ◽  
The United States ◽  
Bridge Girders ◽  
Concrete Bridge ◽  
Approximate Methods ◽  
Standard Design ◽  
Prestressed Concrete Bridge ◽  
Precast Prestressed Concrete

Many bridge owners have developed new precast, prestressed concrete bridge girder sections that are optimized for high-performance concrete and pretensioning strands with diameters greater than 0.5 in. (12.7 mm). Girder sections have been developed for increased span capacities, while others fill a need in shorter span ranges. Accurate geometric properties are essential for design. Common properties, including cross-sectional area, location of centroid, and major axis moment of inertia, are generally easy to compute and are readily available in standard design references. Computation of the torsion constant is a different matter. This paper presents the methods and results of a study to determine the torsion constant for many of the modern precast, prestressed concrete bridge girders used in the United States and compares the results with values from the approximate methods of the AASHTO LRFD specifications.

Influence of Thermal Sweep on Girder Stability during Construction

2018 ◽  
Vol 2672 (41) ◽  
pp. 44-55
Author(s):  
Jeffrey M. Honig ◽  
Zachary S. Harper ◽  
Gary R. Consolazio
Keyword(s):  
Prestressed Concrete ◽  
Precast Concrete ◽  
Solar Heating ◽  
Bridge Girders ◽  
Concrete Bridge ◽  
Design Standards ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Fabrication Tolerances ◽  
Type V

During construction, girder stability of precast, prestressed concrete bridge girders is adversely affected by fabrication imperfections. Consequently, limits on lateral sweep imperfection caused by fabrication tolerances are imposed by design standards, thus reducing the possibility of girder instability and rollover. However, thermal sweep, induced by solar heating during early stages of construction, can add to pre-existing fabrication tolerances thereby amplifying girder imperfections and reducing stability. In the present study, lateral thermal gradients available in the literature were adopted and enhanced for purposes of computing thermal girder sweep. A variety of girder types—PCI BT-63, Florida-I Beams, and AASHTO Type-V—were then investigated to quantify the influence that lateral thermal sweep has on the stability of individual precast concrete bridge girders under lateral wind load. Previously validated finite element analysis modeling and analysis techniques were used to conduct a parametric study that included 10 girder types, varying span lengths, and five geographic locations. Results revealed that thermal sweep may cause wind carrying capacity reductions of the order of 30 to 60% for typical span lengths, and even greater reductions at span lengths that approach maximum design limits. Consequently, it is crucial that thermal sweep, caused by environmental solar-heating conditions, be considered in construction-stage girder stability analyses.

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