| Because of its superior toughness and weldability, high performance steel (HPS) has gained increasing popularity for use in highway bridges. Its fatigue resistance, however, is not yet well characterized. Established analytical methods that can predict both fatigue crack initiation and propagation, coupled with a material-based testing program, provide a sound and cost effective approach to studying fatigue behavior of HPS.; In order to obtain the necessary material input parameters for the proposed methods, and to better understand the properties of high performance steel, material tests were conducted on ASTM A709 HPS 485W steel and on two conventional structural steels to characterize their monotonic and cyclic material properties. HPS 485W steel shows high strength and good ductility, resulting in high fracture toughness. Fatigue test results, however, indicate that HPS 485W steel exhibits a fatigue resistance comparable to that of lower strength and toughness structural steels but with significantly higher fatigue limit.; Fatigue life prediction analysis was performed on six common structural details of which test results are available in literature. The proposed methods predicted fatigue lives of all details well, comparing with the test results. HPS shows slightly higher fatigue resistance than conventional structural steels in the high cycle fatigue region for non-welded details. However, fatigue resistance of HPS welded details is similar to that of conventional structural steels welded details. The current fatigue design provisions are still applicable to HPS welded details. |
