Load Rating of a CIP Open Spandrel Arch Bridge With Curved Widening and Offset Traffic Pattern Using

Presented BY: Soroush Fakhri Yazdi, P.E.

This presentation is about load rating of 11 span spandrel arch bridge with a major widening that shifted the traffic pattern, which could not be analyzed without using 3D refined model. Arches traditionally perform well by reducing the bending moment caused by vertical load and converting it into load into the axial load. This feature is most effective when the arch is loaded evenly. 

The open spandrel arch bridge carrying Rte. 58 over Smith river was built in 1927. In 1961 the deck was widened on one half of the arch to create a curved roadway alignment. The design engineers at the time added counterweight to the opposite side of the bridge for balancing the force flow through the supporting arch. The offset portion of the roadway was supported by a cantilever structure extended from the original spandrel arch.

This paper investigates the behavior of the bridge superstructure under standard AASHTO vehicles using 3D FEM, which proves to be a cost effective and precise analysis for load rating such sophisticated structure. Certain assumptions are made in modeling such complex system to simplify the process. This work will appraise these assumptions and different boundary conditions used in the model to determine what assumptions will lead to most realistic results. The results from 3D model showed that the counterweight added did not help balance the distribution of internal forces. In this paper traditional methods of calculation are used to better understand why the design engineers used such counterweight.

The behavior of the unusual arch widening will be explained to attendees. These topics are not only useful for bridge load ratings, but will develop the concepts of rehabilitation and future widenings of open spandrel arches. Additionally, challenges and findings throughout the structure analysis and load rating will be presented.

SPEAKER BIOS

Soroush Fakhri Yazdi is an achievement-oriented senior structural engineer with a solid educational background, and extensive finite element analysis experience. Soroush has more than 12 years of experience in project management, review, and design of Highway Structures in several states. He also has experience with many maintenance and rehab projects as well as evaluation of complex bridges. He has taught Structural Analysis as an Adjunct Professor at GMU’s Civil Engineering program. Soroush is knowledgeable of numerical analysis of structures using several FEM programs. He has published a paper in Analysis of a Horizontally Curved I-Girder Bridge for Blast Loading and Load Rating of a CIP Open Spandrel Arch Bridge With Curved Widening and Offset Traffic Pattern Using Refined Method of Analysis.