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针对大型桥式起重机静载试验大吨位载荷加载困难影响起重机结构安全评价的问题,基于起重机结构设计理论,提出了大型桥式起重机降载当量试验方法,并对降载计算及计算误差进行了探讨。由相似理论建立位移、变形与载荷的关系,以确定相似控制量,通过测试起重机起升载荷较小时的变形和位移,推断起重机起升载荷为极限值时的变形和位移情况。通过逐级加载的方式测试与大型桥式起重机结构特性近似相似的50 t中型双梁桥式起重机跨中截面危险点的应力,将测试应力值与理论计算值进行比较。结果表明,适当降载比例的降载试验能实现一定精度的结构响应预测,可用于起重机结构安全评价。
According to the structural design theory of crane, this paper puts forward the test method of load-equivalent for large-scale overhead cranes, and discusses the calculation of load-shedding and calculation error . By the similarity theory, the relationship between displacement, deformation and load is established to determine the similar amount of control. By testing the deformation and displacement of the crane when the lifting load is small, the deformation and displacement of the crane when the lifting load is the limit value are deduced. The stress of cross-section cross-section of 50 t medium-sized two-girder overhead traveling crane with similar structural characteristics to that of large-scale overhead traveling crane is tested step by step. The test stress is compared with the theoretical value. The results show that the load-shedding test with appropriate load-shedding ratio can predict the structure response with a certain accuracy and can be used in crane structural safety assessment.