TECHNICAL FABRICATION ISSUES WITH STEEL ORTHOTROPIC BOX GIRDER BRIDGES, 2004
The technical difficulties with the fabrication of steel orthotropic box girder (OBG) bridges became very apparent during the construction of the third bridge crossing the Carquinez Strait at the town of Crockett, California. The new Carquinez Bridge has been officially designated the Alfred Zampa Memorial Bridge by the California Legislature. The Alfred Zampa Bridge (AZB) is located 20 miles northeast of San Francisco on I-80 and is in close proximity to several active seismic faults. The bridge was opened for traffic on November 8, 2003. The first and most complicated issue discussed in this paper is the welding of the partial joint penetrations (PJP) groove weld connecting the stiffening troughs to the steel plates of the deck, soffit, and side panels of the OBG. This critical joint in orthotropic steel bridges is prone to fatigue. The weld is subject to both normal forces and bending moments. Fatigue damage to this weld can cause significant damage to the function of the composite behavior of the steel girder box and its pavement. In addition, the repair of such a weld is extremely costly should this weld experience any fatigue damage. This paper will discuss the procedures used in developing, testing, and finally performing this weld on the AZB.
The second technical issue discussed in this paper is the how to address weld-induced distortion in order to achieve the required fabrication tolerances of the OBG. The basic concept of the OBG is to utilize relatively thin steel members in order to reduce the weight of the structure while obtaining orthotropic properties. Since thin steel members are welded together to achieve such properties, the heat distortion is a major consideration when attempting to determine how best to achieve the tight tolerances for the finished geometry of the structure. This paper will discuss some of the technical difficulties encountered during the fabrication of the components of the OBG for the AZB.
– Mazen Wahbeh, Brian Boal, Jim Merrill, August 21-24, “Technical Fabrication Issues with Steel Orthotropic Box Girder Bridges,” ASCE Othotropic Bridge Conference, California, USA, 2004.