Transbay Joint Powers Authority outlines seismic design and glazing approach for new Transit Center

Robert Beck, Senior Program Manager for the Transbay Joint Powers Authority, presented the seismic‑safety design for the new Transbay Transit Center, focusing on structural performance and the design of a glass curtain wall.

Beck said the program replaces the existing Transbay Terminal, extends Caltrain alignment into the new center and anticipates future California high‑speed rail. The structure is being designed for an M8 event (described in the presentation as a 975‑year event on the San Andreas Fault), with the objective that the building remain structurally functional and occupiable after such an event even if repairable damage occurs.

On the skin of the building, Beck described independent panels (about 85 feet long) separated by roughly 6‑inch gaps and mounted on hinged frames that accommodate differential displacement. Each glazing panel is composed of two 10‑millimeter glass panes laminated with a 1.5‑millimeter interlayer, producing a composite glazing thickness the presentation said exceeds three quarters of an inch. Corner supports and neoprene gaskets allow movement and are intended to hold laminated glass in the frame if breakage occurs, preventing blowout.

Beck said testing plans include shake testing for structural frame components and blast‑resistance testing of glazing anchors (testing for seismic racking of glazing is secondary to blast criteria in current plans). He also acknowledged that extremely large blast events (citing Oklahoma City as a scale example) would overwhelm the system.

During questions a council member asked whether on‑site field testing would be performed; Beck confirmed targeted tests on structural frames and glazing anchors.

The presentation did not propose or trigger a formal action; council thanked the presenter and moved on to the next item.