A Report of the Investigation on Steel Bridge Design Criteria to Help Minimize the Probability of Fracture; Project IHR-304, Illinois Cooperative Highway Transportation Research Program

In this study the nature of actual random traffic stress histories in steel beam or girder highway bridges has been investigated. Quantitative field test results have been used to develop mathematical models that can be used to represent the stress histories for such bridges. The beta distribution function has been found to be an effective mathematical model for the actual stress-range histograms and has been used to establish random stress factors and can be used in fatigue design to account for the random nature of loadings in highway bridges.State of Illinois. Department of TransportationU.S. Department of Transportation. Federal Highway Administratio

Report on Phase 2.3, Investigation of Welded Highway Bridges. Project IHR-64

The object of this investigation was to study the effect of internal flaws on the fatigue behavior of butt-welded connections in mild structural steel, the initiation of fatigue cracks from these flaws and the propagation rates of these cracks in the connections. Since internal flaws occur in many welds it is essential to obtain a better understanding of the behavior of flawed connections so that adequate, yet realistic, code requirements can be established. The study is limited to two major types of defects, porosity and incomplete penetration. The porosity was further subdivided into two categories based on the severity of the defect. The specimens with incomplete penetration were made with an initial 3/16" centrally located crack the full width of the- specimen. The fatigue behavior of the connections with the defects is compared with that of sound welds to observe the effects of the defects on the fatigue strength of the connections. The data are compared with result~ of similar studies found in the literature and also with the AASHO 1970 Specification design requirements. Three of the specimens with incomplete penetration were examined radiographically during the fatigue testing to determine when initiation of the fatigue cracks occurred, and how rapidly they propagated. The results of the crack propagation tests are compared with similar relationships developed for high strength steels. A relationship that better fits the data for mild steel has been developed in a manner similar to that used for the high strength steels.State of Illinois. Department of Transportation. Division of HighwaysU.S. Department of Transportation. Federal Highway Administratio

Fatigue Behavior of Welded Joints and Weldments in HY-80 Steel Subjected to Axial Loadings

Bureau of Ships, U.S. Navy.Contract N0bs 77137Index No. NS-021-20

Evaluation of Flow and Fracture Propensity of Notched Steel Plates by Means of a Photoelastic Model

Ship Structure Committee. Bureau of Ships, U.S. Navy.Contract NObs 88283Project Serial No. S-F 013 0304, Task 2022Project SR-14

Effect of Notches on the Axial Fatigue Properties of Structural Steels

The effect of the stress concentration on the zero-to-tension axial fatigue strength of notched members of four structural steels has been studied. For each of the four steels a critical notch severity was found at which a transition in behavior takes place. When the theoretical stress concentration exceeds this critical value the fatigue strength increases instead of continuing to decrease as would normally be expected. The maximum effective stress concentration determined from these tests corresponds to a critical notch severity which is dependent on the material) the geometry of the specimen) and the cyclic conditions of stress. Microscopic examinations of the roots of the notched specimens which did not fail revealed cracking in most cases. Some of the cracks apparently were nonpropagating cracks but the test lives in most cases were insufficient to isolate such cracks positively as non-propagating. A study of other data on non-propagating cracks revealed that the laws governing their formation are not yet fully understood. However, there are indications that the increase in fatigue strength obtained above the critical notch severity is coincident with the formation of non~propagating cracks.The Engineering FoundationAmerican Iron and Steel InstituteChicago Bridge and Iron FoundationThe Welding Research Counci

Tests of Welded Copper Joints

The Copper and Brass Research Associatio

Effect of Repeated Loads on the Low Temperature Fracture Behavior of Notched and Welded Plates

The influence of repeated loadings on the susceptibility of weldments to fracture in a brittle manner is studied for an ABS-Class C steel. The test members have consisted primarily of 12, 24 and 36 in. wide notched-and- welded specimens that, at low temperatures, have been known to provide low-stress brittle fractures. The repeated loads or loading history are found to affect the fracture behavior of the weldments. In all but one instance the fracture stresses obtained for the notched-and welded wide plates were greater than the stresses to which the members had been subjected during the repeated loadings. Furthermore, the repeated loadings appeared to eliminate the two-stage fractures observed in some of the tests of as-welded specimens. This latter condition is in general desirable, but only if the fracture stress is raised to a high-stress level.Bureau of Ships - Department of the Navy Contract NObs 88283 Proj ect SR-149 Ship Structure Committe

Fatigue and Static Properties of Welded Joints in Low Alloy Structural Steels

Ohio River Division LaboratoriesCorps of Engineers, U.S. Army.Contract No. DA-33-eng-25

Crack Propagation in Low-Cycle Fatigue of Mild Steel

Ship Structure Committee. Bureau of Ships, U.S. Navy.Contract NObs 77008Index No. NS-731-034Project SR-14

Effects of Repeated Loadings on Structural Connections with High-Strength Bolts

Research Council on Riveted and Bolted Structural JointsThe Division of Highways. State of Illinois.The Bureau of Public Roads. U.S. Department of CommerceProject I