Collapse of U.S. 35 Highway Bridge, Point Pleasant, West Virginia, December 15, 1967 (HAR-71/01)

The results of these investigations, reported in February 1969 (Reference 29), show that the material of the eyebars was susceptible to fretting-fatigue, and that such action could reduce the fatigue life at a given stress range, as compared to rotating beam specimens of equal initial surface finish, by about 17 percent, as indicated by the S-N curves of Figures 31a and 31b. On a basis of these data, Professor Starkey estimated that the material in the critical location at the edge of the pinhole would have a life expectancy of about 200,000 cycles, assuming nominal stresses in the shank of the eyebar to vary from 40,000 psi. to 50,000 psi. and considering the effects of stress concentration and fretting. However, he also pointed out that the presence of water in the joint would contribute further to the acceleration of fatigue damage by the mechanism of corrosion-fatigue, possibly reducing the life by as much as 50 percent, thus approaching the 73,000 cycles would correspond to five cycles per day for 40 years. Professor Starkey concluded his report with the observation that the static proof tests of the eyebars did not relate in any way to the ability of the bar to sustain the high local stresses in the head over a long period of time and under variations of load.

## 6. Static Tests of a Full-Scale Eyebar at Lehigh University

A tension test of a full scale eyebar removed from the wreckage on the Ohio shore was performed at Lehigh University in April of 1969 at the direction of the firm of Modjeski and Masters, consultants to the West Virginia Department of Highways. The eyebar used had a nominal length of 25 feet, 4 inches between pin hole centers, and was one of the elements in the north chain between panel points 0 and 1. The bar was loaded in the large universal testing machine by means of clevis connections. The pins were 10 inches in diameter but were fitted with sleeves made from one of the 11-1/2 inch diameter pins removed from the Point Pleasant Bridge wreckage. The length of the pin between the inside faces of the clevis yoke was 10-1/2 inches.

The eyebar was loaded in increments of 50,000 lbs. up to a load of 400,000 lbs., then by increments averaging about 100,000 lbs. until some definite yielding was observed at 1,775,000 lbs. At this time, load was reduced, then the extensometer was removed. Loading was then applied and raised until a fracture was produced in the shank of the bar near its midlength at a load of 2,450,000 lbs. This corresponds to a unit stress of 112,000 psi. in the shank of the bar. Analysis of the data from the test indicated that the actual yield load was 1,650,000 lbs., corresponding to a unit stress of 76,040 psi. in the shank. The percent of elongation measured over an 18 foot gage length was 8.54 percent. The reduction of area at the fracture was 30.55 percent.

Both faces of one head of this eyebar were extensively strain gaged to assess stress concentration factors under load. The stress concentration factors averaged 2.64 on the left side of the hole and