Title:
Box Girder Bridge Deflections
Author(s):
Vladimir Kristek, Zdenek P. Bazant, Milos Zich, and Alena Kohoutkova
Publication:
Concrete International
Volume:
28
Issue:
1
Appears on pages(s):
55-63
Keywords:
box girder bridges; creep; drying; humidity effects; long-term deflections; prestressed concrete; serviceability; shrinkage.
DOI:
Date:
1/1/2006
Abstract:
Long-span prestressed concrete box girders typically exhibit deceptively small deflections, possibly even upwards. However, after about 3 to 10 years, deflections may begin to increase rapidly. To predict deflections correctly, a creep and shrinkage model that realistically describes the moisture diffusion process must be used to calculate the delay of shrinkage and drying creep of the thick bottom slab. The effects of this delay are discussed, and comparisons are made to measured deflections of actual structures.