SEAOI Workshop: Designing Cross-Frames & Diaphragms for Steel Bridges

Cross-frames and diaphragms are important steel bridge components--they provide stability to primary longitudinal girders and improve the bridge system's lateral or torsional stiffness and strength during construction and in-service. In horizontally curved bridges, they transfer forces between adjacent girders to provide equilibrium. In straight bridges, they have been historically designed to transmit wind loads.

Over the past few years, the steel bridge industry has seen a general increase in the size of cross-frames used in steel I-girder bridges across the country, in terms of both the individual member sizes and the connections themselves, resulting in significant inefficiencies. On a cost per pound basis, the cost to fabricate cross-frames can be the most expensive part of any steel girder bridge project.

This workshop will review the design history of cross-frames and guide designers to make better choices regarding cross-frame layouts, type, members, connections, loads, analysis, and design. The workshop will walk through design decisions for cross-frames in bridges that are straight with low skew, straight and heavily skewed, and horizontally curved with skewed supports. The workshop will cover efficient cross-frame and framing plan layout decisions, analysis considerations, stability requirements, design loads, member design, and connection design for each bridge type. We will also discuss fabrication techniques for cross-frames and diaphragms, explaining why certain decisions will result in more efficient fabrication of cross-frames.

  • Location: Association Forum 10 S Riverside Plaza, Ste. #800 Chicago, IL 60606
  • Date: September 14, 2022 - 8:00 am to noon

For more information, click here.