Bridge Failures - Failure Case Studies in Civil Engineering - page 64

POINT PLEASANT BRIDGE — SILVER BRIDGE
(1967)
The Point Pleasant I-bar suspension bridge between Point Pleasant, West Virginia
and Kanagua, Ohio which was built in 1928, failed at 5:00 p. m. on December 15,
1967. Forty-six people died in the accident and thirty-seven vehicles on the bridge
fell with the bridge.
The center span was 213 m (700 ft) long and the side spans were 116 m (380
ft) each. The bridge was unique in that the stiffening trusses of both the center span
and the two side spans were framed into the eyebar chain to make up part of the
stiffening truss.
Investigation of the failure indicated that the collapse of the Point Pleasant
Bridge was caused by a defective eyebar at joint 13 of the north chain, approximately
15 m (50 ft) west of the Ohio Tower. The bar which connected Joint 11 to Joint 13
developed a cleavage fracture in the lower portion of its head. Once the continuity of
the suspension system was destroyed the bridge collapsed suddenly.
Lessons Learned
An eyebar suspension bridge is not a redundant structure. Failure of one eyebar is
sufficient to cause collapse. If a bridge of this type is to be constructed, close and
frequent inspection of the structure is necessary.
The tragedy of the failure of the Pleasant Point Bridge led to the national
policy for bridge inspections. In 1968 the United States Congress enacted the
National Bridge Inspection Standards (NBIS).
References
Ballard, W.T. (1929). "An Eyebar Suspension Span for the Ohio River," ENR , June
20, 997-1001.
Bennett, J. A. and Mindlin, Harold (1973). "Metallurgical Aspects of the Failure of
Point Pleasant Bridge," Journal of Testing Evaluation , ASTM, I(.2), 152-161.
Dicker, Daniel (1971). "Point Pleasant Bridge Collapse Mechanism Analyzed," CE ,
July, 61-66.
ENR. (1967). "Collapse May Never be Solved," ENR , December 21, 69-71.
ENR. (1968). “Possible Key to Failure Found," ENR , January 1, 27-28.
ENR. (1968). "Point Pleasant Bridge Failure Triggers Rash of Studies," ENR ,
January 4, 18.
ENR. (1968). “Collapsed Silver Bridge is Reassembled," ENR , April 25, 28-30.
ENR. (1969). "Bridge Failure Probe Shuts Twin," ENR , January 9, 17.
National Transportation Safety Board (NTSB). (1968). Collapse of US 35 Highway
Bridge, Point Pleasant, West Virginia, December 15,1967 Highway Accident
Report , NTSB, Washington, D. C., October 4.