Transcript The Mianus River Bridge Collapse Group 11.ppt

The Mianus River Bridge
Collapse
Background


A cantilevered multi span structure
Two suspended spans supported from
main spans
Bridge Construction


“Pillow block cradle” and “pin and hanger” design
Problematic construction as no redundancy
measures
How it Failed




Rust builds between
plates and pins
SE Hanger plate slips
off pin (rust and
lateral forces)
NE Hanger fails due
to added load
West end falls from
cradle and bridge
collapses
Failure…



As well as the corrosion
the bridge endured
heavy lateral loads
Forces due to the
acceleration and
breaking of the cars
These forces may have
helped pop the pin cap
off
Lessons Learned




Regular checks on bridge drainage
Improved bridge inspection (execution and
guidelines)
Cleaning of critical bridge elements
Investigate other pin and hanger bridges,
particularly those with no redundancy
measures