大型门式起重机风荷载响应仿真分析

Simulation analysis of wind load response for large gantry crane

风荷载是起重机设计及运行时的重要荷载,近年来门式起重机呈现"大型化""柔性化"的发展趋势。大型门式起重机受其结构特性影响,对风荷载极其敏感,现行《起重机设计规范》仅通过风力系数及挡风折减系数对起重机迎风面的静风荷载进行界定,因而无法获得起重机各表面的风荷载分布情况。为解决这一问题,利用计算流体力学(computational fluid dynamics,CFD)软件对大型门式起重机的风场绕流特性进行仿真分析,并运用单向流固耦合方法将风荷载数据引入起重机计算结构力学模型并进行有限元分析,从而获得自然风场中大型门式起重机的风荷载响应,并将它与根据《起重机设计规范》计算得到的结果进行对比。结果表明:利用计算流体力学仿真分析得到的起重机整机风荷载与根据《起重机设计规范》计算得到的结果相近,但基于流固耦合方法所得的起重机结构应力大22.77%,结构应变大17.23%,这是因为自然风场中起重机各表面均受风荷载影响,而《起重机设计规范》仅对迎风面风荷载进行量化,忽略了流体在非迎风面产生的负压以及黏性力作用;门式起重机的主梁及支腿为串列结构,上游结构对下游结构有屏蔽效应,使得下游结构表面为负压,且屏蔽效应随着上下游结构间隔比的增大而减弱。研究结果可为起重机的设计校核提供参考。

Wind load is an important load in crane design and operation. In recent years, gantry cranes have shown a development trend of "large-scale" and "flexible". Large gantry crane is increasingly sensitive to wind load due to its structural characteristics. However, the current Design rules for cranes only defines the static wind load on the upwind surface by the wind force coefficient and wind shield reduction coefficient, so that the wind load distribution on each surface of the crane can not be obtained. To solve this problem, the wind flow characteristics of large gantry crane were simulated by the computational fluid dynamics(CFD) software.Then, by using the unidirectional fluid-solid coupling method, the wind load data was introduced into the computational structural mechanics modelof crane and analyzed. Finally, the wind load response of gantry crane in the natural wind fieldwas obtained and compared with the calculation results according to the Design rules for cranes. The results showed that the wind load of the crane by using the CFD simulation was similar to that calculated according to the Design rules for cranes. However, the structural stress and structuralstrain of the crane obtained based on the fluid-structure coupling method were 22.77% and 17.23% larger, respectively.This was because each surface of the crane was affected by the wind load in the natural wind field, but the Design rules for cranes only quantified the wind load on the upwind surface, while ignoring the negative pressure and viscous force effects on the non-windward surface. The main beam and outriggers of the gantry crane were in tandem structure, and the upstream structure had a shielding effect on the downstream structure,which led to negative pressure on the downstream structure surface, while the shielding effect weakened with the increase of spacing ratio between the upstream and downstream structures. Resecrch results can provide a reference for the design and verification of large gantry cranes.