Silver Bridge
38 845 - 82.141111111111Koordinaten: 38 ° 50 '42 " N, 82 ° 8' 28 " W
F1
Ohio River
The Silver Bridge ( officially the Ohio River Bridge ) was a chain bridge over the Ohio River, which from 1928 until its collapse in 1967 linked the city Point Pleasant, West Virginia and Kanauga, Ohio together.
- 3.1 Accident Analysis
- 3.2 knock-on effect
History
The General Corporation and the American Bridge Company constructed the two-lane suspension bridge, which was specified according to the guidelines of the American Society of Civil Engineers. She was the first bridge of its kind in the U.S.. The 681 m long bridge was completed on 30 May 1928, got its name because of the aluminum coating used for the first time.
Construction of the Silver Bridge
Carrying chains
The supporting chains of the Silver Bridge consisted of continuous tension members, so-called eye rods, which were bolted together at their eyes closed. This type of design was successfully implemented at the time of completion for more than 100 years. Until then such bridges were always designed with four -to six- fold redundancy, as was done in the designed by Isambard Kingdom Brunel English Clifton Suspension Bridge by 1864. This very old suspension bridge is traversed as before and demonstrates the structural reliability of such bridges.
The supporting chains of the Silver Bridge were carried out only with two rods made of heat treated, hardened steel, which had twice the tensile strength of ordinary steels. The break one of the poles can lead to sudden overuse of the other rod. In carrying chains with low redundancy, therefore, the security is highly dependent on the flawless production and assembly of components.
Buttress
The pylons were designed as 40 m high vibration pillars that were not rigidly connected at its base to the foundation. Thus, the bridge load change, vibration and temperature fluctuations could absorb, without overloading the suspension chains. The pylons required as a result the suspension chains on both sides as a support, and therefore a break in one of the carrying chains led to failure of the entire bridge.
Load acceptance
At the time of construction weighed a typical family cars like the Ford Model T about 680 kg. The maximum allowable total weight of a truck was approximately 9000 kg. 40 years later, at the time of the bridge collapse, the vehicle weight is a brand new Ford Mustangs already amounted to twice, namely 1400 kg, and large U.S. trucks weighing up to 27,000 kg. The traffic density had multiplied during the period.
Collapse
On December 15, 1967 17:04 clock the Silver Bridge collapsed. Because of the tight closing time traffic were at the time of the accident 37 cars on the bridge, of which 31 fell into the Ohio River. 46 people died and nine were seriously injured.
Accident Analysis
The four-year study of debris called a cleavage fracture on the connecting rod 330 due to an undetected manufacturing defect as the cause of the disaster. A minor structural defects introduced by corrosion and fatigue failure of the eye rod.
Knock-on effect
President Lyndon B. Johnson decreed in response to the misfortune of a nationwide review of all bridges on their reliability. 1800 bridges were currently already operating age of 40 years, of which 1100 were still specified on the load of a Ford Model -T. The collapse of the Silver Bridge led in this way to improved material testing, logged scheduled inspections and ultimately to the demolition and reconstruction of some older bridges.
The construction of the Silver Memorial Bridge was announced on February 8, 1968 by Lyndon B. Johnson and completed exactly two years after the disaster on 15 December 1969.
The bridge collapse has been associated with apparitions of the legendary figure of Mothman related recorded by journalist John A. Keel in his 1975 book The Mothman Prophecies. In them the film is based The Mothman Prophecies of 2002.