Research On Fatigue Performance And Reinforcement Method Of A Crane Beam

With the continuous development of the economy in China and the further reformation and transformation of the industrial plants,the steel demand has dramatically increased,which makes the production work in metallurgical plants much heavier.Due to the frequent use,the fatigue life of well-functioning steel crane girder is greatly shortened.Fatigue cracks appear on the steel crane beams in the most frequently operated sections because of heavy workload and complex working environment such as high temperature,high dust,etc.Therefore,fatigue damage now has become the major cause of fatigue failure in steel crane beams.Besides,since this fatigue damage is a process of cumulative damage,and its damage to steel is a brittle failure,it will pose great danger to the security of human life and property once it occurs,and cause the pause of production activities as well as huge economic losses.In a word,it is of increasing practical significance to conduct the on-site inspection of the existing steel crane beams to discover the potential dangers in time and check the fatigue strength.In this paper,the on-site inspection of in-service steel crane beams was conducted in a metallurgical plant to get knowledge of the current condition of the existing steel crane beams.Then three representative crane beams were selected as the test subjects from the feeding span,molten steel receiving span,and billet exit span,the ones which were the most frequently used in the production and operation.Strain gauges were pasted at the measuring points of the steel crane beams.The statistical analysis of the data acquired in the dynamic stress test by the rainflow counting method was conducted to obtain the corresponding Equivalent coefficientα_fof each tested span.After the analysis of the real operating conditions of the crane on the beam through numerical simulation,the stress change curve at the measuring point of each steal crane beam,the maximum shear stress at the beam end,and the maximum real stress was extracted.When the maximum stress amplitude was found,the fatigue strength was checked and the arcs that did not meet the requirements of the fatigue strength verification were subsequently reinforced by the method of“oblique brace”and CFRP.After that,the influence of the size of the“oblique brace”on the reinforcement effect was analyzed based on the exploration of the optimal reinforcement effect of the different inclination angels,using the finite element simulation.The optimal reinforcement effect of one layer and two layers of CFRP pasted on the arc was also explored,which would be of great enlightenment to future studies on the reinforcement of similar engineering crane beams.