Stability Analysis Of Huge Box Variable Section Leg Of Shipyard Gantry Crane

With the development of national economy, the shipbuilding industry of our country is developing rapidly and there is an increasing demand for shipyard gantry cranes. The shipyard gantry crane has the features as long span, high leg, and big lifting weight, which usually adopts a structural form of one rigid leg and one flexible leg. The section of rigid leg belongs to variable box section, and there is no clear regulation on selecting effective length coefficient when calculating the overall stability of this kind pillar. At the same time, the leg has a thin-wall box section,which results in the larger width to thickness ratio of plates. So how to take the appropriate construction measures to ensure its local stability is a problem worthy of study.This paper takes the CS1500/1000×87 double-beam shipbuilding gantry crane that Xin Da Fang Limited Company develops for Singapore as research sample, set up finite element model by using software Ansys, analyze the stability of the leg with huge box variable section, and the main works is as follows:(1)Introduce the theory of structural stability and analysis method in detail,mainly the calculating method of critical load.(2)Set up overall stability analysis model of gantry crane with BEAM189 element, find out the critical stress when the rigid leg of gantry crane happen to eigenvalue buckling in different stiffness ratio of beam and pillar by changing the height, span and sectional properties of beam and pillar.Obtain effective length coefficient of the leg by comparing with Euler’s formula. Fit formula respectively to get estimate calculation formulas of effective length coefficient of the rigid leg of constant cross-section and variable cross-section.(3)Establish local stability analysis model of the rigid leg with SHELL181 element, which is used for geometry nonlinear analysis and material nonlinear analysis to get the nonlinear buckling load.On the condition that nonlinear buckling load of the local stability is not lower than the buckling load of the overall stability,study reasonable and effective construction measures for the local stability, study the influence of diaphragm plate on local stability.The results of the paper can provide certain reference for the design of the leg of shipyard gantry cranes and the column of large thin-wall box section.