This bridge is an excellent example of structural design from the days long before computers. Both photos show "pinned connections" which are cylindrical pins secured at their ends by hex nuts. In such connections, the member is free to rotate about the pin. They were (and are) used because they result in zero bending moment about the axis of the pin, thereby eliminating bending stress in the member. Only tension/compression stresses remain. It appears that pinned connections are used throughout the South Norwalk truss bridge.
MELGAR
Serenska posted:One of my favorite parts of that bridge is located along the base. The diagonal, vertical, and horizontal side struts are all supported by would looks like an operable hex "nut" about 1-2 feet in diameter. When passing over or under, I always imagine a large crescent wrench being used to tighten 'er up. The photo below shows one of these:MELGAR posted:
Second photo shows the adjacent truss bridge which carries the 4-track mainline across the intersection of Main and Washington Streets in South Norwalk. Both photos taken while on a Metro-North train from Danbury to Norwalk on June 1, 2017.MELGAR
July 30, 2019 MELGAR removed photo posted by Serenska.
Steven J. Serenska
