Research for the Crane Boom Length Coefficient Considering the Tower Head Flexibility in Rotary Plane

When the crane boom length in rotary plane is determined, the traditional methods only consider support condition, non-uniform, boom end lateral displacement constraint effect of amplitude dragline and hoist rope tensile forces. Ignoring tower head elastic deformation will cause false analysis results. The feasible method is following: not only consider support condition, non-uniform, boom end lateral displacement constraint effect of amplitude dragline and hoist rope tensile forces but also consider the tower head flexibility. The tower crane boom in-of-rotary-plane stability is studied, which has a flexible tower head and rope end displacement constraint. By the equivalent elastic support method, the small deflection buckling differential equation of the tower boom with non-conservative loading is established in critical condition. According to the buckling boundary conditions, the expressions for the deflection curve, Euler critical load and length coefficient of the crane boom are obtained in rotary plane after considering the tower head flexibility. Taking a constant section and length boom as an example, the tower head flexibility effect on the length coefficient is analyzed in rotary plane. In the same working case, the boom length coefficient after considering tower head flexibility is larger than the length coefficient without considering tower head flexibility in rotary plane. The worse the tower head rigidity, the larger the boom length coefficient in rotary plane.