Last February I worked on a rating for MassDOT on two simple span prestressed concrete I-beam bridge with an 8" composite deck. The bridges were built in 1982 and carries route 146 through Sutton MA. The bridges span 78'-4" with a 8°-22'-09" skew.
I used Virtis to perform the rating of the prestressed concrete I-beams. The rating of the reinforced concrete deck was computed by hand in accordance with the AASHTO Standard Specifications and MassHighway Bridge Manual.
The prestressed concrete I-beams have a set of 16 straight low relaxation strands and 7 harped or draped relaxation strands. At first I had trouble modeling the beams in Virtis and would come up with rating factors lower than 0.05. At first I thought the strand pattern may have been incorrect or a material was entered wrong. After exhausting all the typical mind fart errors, we were able to figure out a problem with the live load modeling.
When we inspected the bridge to confirm measurements and gather other information we noticed that the majority of the prestressed beam ends had areas of rust staining with minor cracking throughout but nothing serious enough to effect the rating.
No comments:
Post a Comment