Research On Stress Mechanism Of Steel Crane Beam Under Dynamic Load

Present research on steel crane beam more focused on the theory and model test, and underthe dynamic load the stress performance measurement research of heavy duty steel crane beamis almost blank.Through the methods of field test and finite element simulation, this article have researchedthe stress of the steel crane beam under dynamic load. Field test, chose four crane beam as testobject, which have different span and bearing form.Then in full load, the rated load and no-loadthree conditions, collected the strain value of stress concentrated parts (bearings, flange andweb on junction), when crane driving and the car driving along the workshop transversevertical direction along the plant. Later the test data are analyzed. By create the finite elementsimulation of the three crane beam, analyzed the stress of the steel crane beam bearing and theadditional bending stress on the web of the biggest bending moment on the crane beam, whenthe crane rail eccentricity e grew gradually (increases from0to web thickness), and the verticaleccentric loading and lateral horizontal braking force work together on the beam. Finally thestress state of two kinds of variable cross-section bearing which are the circular arc transitiontype and rectangular mutations is analyzed, and compared the fatigue resistance performance oftwo kinds of variable cross-section bearing.The results show that, using flange bearing in the form of a simply supported crane beam,the support side has stress concentration phenomenon. When the crane is operated frequently,the support side has stress concentration phenomenon and the location is easy to producefatigue crack. The crane girders arc variable cross-section, the first principal stress act on thearc tangent, the second principal stress act on the circular radial, the fatigue crack of the radialand tangential is easy to be seen on the variable cross-section. For rectangular cross-section ofbearing, on the premise of meet the requirements of a certain structure, its anti-fatigueperformance is better than arc variable cross-section bearing. When the eccentricity e increases,the stress of the eccentric crane beam flange and web on the side of the border increasedgradually. When the gap of the eccentricity is4mm, the stress grow up to16%. Eccentricity can lead to larger eccentric crane beam on the other side of tensile strain, thus is advantageousto the top flange and web plate at the junction of the development of the cracks. Because of theeccentric role will worsen the working performance of crane beam upper area, the crane railshould be regularly straightened. Move in eccentric load under the action of reciprocating, thecycle of principal stress and the shear stress is one reason of fatigue damage between the topflange and web junction. Encryption of the crane beam transverse stiffener to improve theworking performance of the web under the vertical eccentric load will play a good effect.