|Title:||Fatigue behavior of steel structures under multiaxial loading from wheel loads: detailed report on the research project|
|Other Titles:||Fatigue behavior of steel structures under multiaxial stresses due to wheel loads|
|Abstract:||In building construction, crane construction and conveyor technology, the movement of goods and machines causes migrating concentrated loads that usually act as wheel loads on the supporting structures, which are usually made of steel. In the area of the wheel load introduction, the connections and connections of these constructions experience a state of stress from local compressive and shear stresses, which are superimposed with global stresses from beam bending and shear force. Since this multi-axis stress state occurs with every roll-over, fatigue damage to the connections and connections can be the result. In contrast to the old national design rules for cranes and crane runways, which contained comparable calculation and strength approaches for the proof of fatigue based on nominal stresses, the new European design rules for cranes and crane runways differ. As a result, a number of construction details with wheel load introduction for cranes are classified as more favorable in terms of their fatigue strength compared to crane runways with identical designs. The notch case classification of these construction details has so far been theoretically derived in all design standards, since there are no corresponding fatigue tests. The difference between the old national and the new European design rules is partly due to a different consideration of the influence of residual stresses on the fatigue strength of welded connections. The European design rules assume high residual stresses and therefore neglect the influence of medium stresses. The notch case catalog of the design standards is limited and, for example, does not contain any classification for the frequently executed construction detail of the welded-on crane rail with wheel load introduction. The limited catalog of notch cases represents an obstacle for the fatigue evaluation of new types of construction. An overview of the known fatigue tests for the construction details with wheel load introduction is given. The well-known evaluation concepts for welded joints with multi-axis fatigue loading are presented. The state of knowledge on the development of residual stresses and their influence on the fatigue strength of welded joints is described. A test program of fatigue tests on crane runway girders with welded-on crane rails and on a new type of crane runway construction with upper chords made of hollow profiles under stationary swelling and rolling over wheel loads is being developed. The investigation of both types of wheel loads takes into account that wheel loads rolling over lead to a non-proportional and stationary swelling wheel loads to a proportionally multiaxial fatigue load. The fatigue strength of the examined crane runway girders is determined on the basis of nominal, structural and notch stresses. When evaluating the multiaxial fatigue stress, both the classic fatigue strength hypotheses and more recent evaluation approaches such as the hypotheses of the critical sectional plane and the integral effort are used. A welding simulation, which is calibrated by temperature measurements during production, is used to derive reference values for the level of residual welding stresses as input values for the fatigue assessment for the crane runway girders with welded crane rails.|
|Appears in Collections:||15 Cross-faculty / other institution|
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