Effect of Welding Procedure on Main Girder Fatigue Property

Hoisting machinery is an important part of the equipment manufacturing industry, and the general bridge crane is the most widely used hoisting machinery. The main girder of bridge crane is the main load-bearing structure. Further, fatigue failure of main girder usually occurs not on the material itself but in the welding joint. The article has carried out three groups of experiments, which are experiment on fatigue property under vertical force, experiment on fatigue property under the comprehensive function of vertical force and horizontal force and experiment on failure mode of main girder under the prefabricated crack, to further discuss the effect of welding procedure on main girder fatigue property. Finally the following three conclusions are obtained. Firstly, the crack occurs closely to the middle position of welding place of the lower board and the main web, with the trend of scaling up along the main web perpendicular to the welding place. Secondly, the crack occurs on the main web close to the upper board, with the two-way expansion trend. Thirdly, fatigue failure cracks do not occur in the welding joint except the prefabricated crack position close to the square steel rail after the cyclic loading of two million times on main girder, which indicates that the uniformity of welding quality has an importance influence on the fatigue reliability of the whole main girder.