Low-Temperature Tests of Simulated Bridge Members

Low-Temperature (—30? F or colder) impulse (impact) tests were performed on six simulated bridge girders after they had been previously subjected to room-temperature cyclic loading corresponding to the AASHO allowable fatique stress. All girders contained cover-plate-end details; three were of A36 steel and three were of A572 Grade 50 steel. The fracture stress for simulated bridge members containing the most critical common structural detail was determined for the worst combination of temperature, strain rate, and prior fatigue loading. In the impulse tests, the specimens were able to reach nominal bending stresses close to the specified minimum yield point of the steel even though they contained severe fatigue cracks that would have caused a fatigue failure in a relatively short time in service. The simulated bridge members had sufficient fracture toughness to prevent premature failure in service.