Brittle Fracture in Cover Plate of Riveted Built-up Bridge Girder Illustrating Member Redundancy

<p>[[Video(http://www.youtube.com/watch?v=AUgiLRhS1jM)]]</p>

<p>This video shows a test in the laboratory in which a 1-inch-thick cover plate was fractured. During the test, the specimen was cooled to -80F to ensure that all materials were on the lower shelf. Then, load was applied to a stress of 0.55F<sub>y</sub>, but no fracture occurred. Next, the specimen was cycled a number of times between 0.45F<sub>y</sub> and 0.55F<sub>y</sub>, but again no fracture occurred. Finally, the wedges were driven into the notch in the cover plate. (This device can be seen attached to the bottom flange.). Under the full load of 0.55F<sub>y</sub>, the cover plate fractured after the wedges were driven using a hydraulic ram. After fracture, the stress on the remaining net section was slightly greater than F<sub>y</sub>. The fracture in the cover plate did not “jump” into the remaining components (i.e., the angles and web plate), indicating that member-level redundancy was present.</p>