Tuesday, October 7

8:00am – 9:30am

(T15) Bridge Design and the LRFD Specifications

 

Track: National Bridge Conference

 

The Dilemma of Prestressed Girder Camber Variability (39), Maher Tadros and Prasan Purisudh, PBS&J, Tampa, FL

 

It has been common knowledge that precast prestressed girder camber at prestress release and at time of erection can vary significantly. This paper addresses several camber issues related to prediction, design and construction.

 

A Review of Shear Rating Procedures (12), David Liu, Shaoyun Sun and Roger Winkelmann, Parsons, Chicago, IL

 

The LFD procedure for shear rating in negative moment region is quite different among DOTs. This study finds the selection of shear rating procedure could change the scope of work and affect the cost associated with rehabilitation of prestressed concrete I-beam bridges.

 

Reliability of Bridge Structures and Their Design Load (44), Reynaldo Pablo, Indiana University-Purdue University Fort Wayne, Fort Wayne, IN

 

Vehicles exceeding truck weight limits are permitted to cross many bridges. As heavier loads cross bridges, the design load may need to be adjusted to maintain an acceptable safety margin. This paper examines the safety and reliability of selected bridges. A new design load is developed as a response to the observed vehicular overloads.

 

I Girder Bearing Design for Improved Stability (38), Maher Tadros, PBS&J, Tampa, FL

 

A number of bridge spans approaching 200 feet have recently been completed, using girders that are 6- to 8-ft deep. Using narrow, thick elastomeric bearing pads has resulted in reduced stability and the possibly of the girders “tipping over.” This paper attempts to review bearing pad design, detailing and specification.