基于许用应力法的桥式起重机金属结构设计验证及安全性评价

发布时间：2018-07-28 15:54

【摘要】：起重机金属结构设计的目的使设计结构具备一定的可靠性,即在经济合理的前提下,在预定的使用期限内使其满足各种预期的功能。历来桥式起重机在我国重型机械中的地位和作用为人们所重视,随着起重机械的发展,其金属结构的重量通常占整机的60%～70%,对于装卸桥这类大型港口机械,金属结构的比重甚至上升到80%～90%。相关统计结果表明,许多起重机事故是由于金属结构失效引起的。当前现役的接近或超过二十年的桥式起重机存在安全生产的隐患,同时受当时各种条件限制,老龄机械设计方案、生产工艺等也不一定适合当前生产的要求,因而对桥式起重机金属结构验证及安全性的评价方法进行研究具有重要的理论意义和工程应用价值。受钢材的锈蚀、环境气候的变化、载荷的变化等因素的影响,起重机在使用过程中其结构性能将随时间而逐渐的退化,引起金属结构部分构件的断裂或损坏,从而将会引起起重机整体结构的失效,因此对现役的起重机的结构验证及安全性的评价引起了工程技术人员的广泛关注。桥式起重机结构的设计验证及安全性评价是我国起重机工程界亟待研究的问题。本文针对这一问题,运用许用应力法,对现役桥式起重机金属结构从设计角度——强度、刚度及稳定性方面进行验证分析,在此基础上结合其他外观因素提出了一种基于贝叶斯网络的理论对现役桥式起重机结构进行现状评价。本文将上述验证过程,依据Visual C++为开发平台,结合Access强大的数据库存储能力,开发出“基于许用应力法的通用桥式起重机结构验证系统”。从影响桥式起重机金属结构安全因素入手,分析目前桥式起重机结构发生事故原因和存在不安全的潜在因素,综合考虑强度、刚度、稳定性及其他外部因素对桥式起重机结构安全的影响,对各因素进行详细的分析,根据其内部的因果关系,建立一种比较实用的桥式起重机结构安全评价指标体系。在对其结构安全进行评价时引入贝叶斯网络,确定网络节点及其值域,进而建立贝叶斯网的拓扑结构,确定了节点的条件概率分布,最终构建了桥式起重机结构安全贝叶斯网评价模型。使用贝叶斯网分析软件包GeNIe软件进行仿真,结果表明,使用贝叶斯网对桥式起重机结构安全评价是可行的。
[Abstract]:The purpose of crane metal structure design is to make the design structure have certain reliability, that is, under the premise of economy and reasonable, make it meet all kinds of expected functions within the scheduled service period. The status and function of bridge crane in heavy machinery of our country has always been paid attention to. With the development of lifting machinery, the weight of its metal structure usually accounts for 6070 parts of the whole machine. For the large port machinery such as loading and unloading bridge, The proportion of the metal structure even rises to 80 and 90. The results show that many crane accidents are caused by metal structure failure. At present, bridge cranes in active service which are close to or more than 20 years have hidden dangers in production safety, and at the same time, due to various conditions at that time, the design scheme of aging machinery and the production process are not necessarily suitable for the requirements of current production. Therefore, it has important theoretical significance and engineering application value to study the metal structure verification and safety evaluation method of bridge crane. Affected by the corrosion of steel, the change of environmental climate, the change of load and so on, the structural performance of crane will degrade gradually with time, which will lead to the fracture or damage of part of metal structure. This will lead to the failure of the whole structure of the crane, so the structural verification and safety evaluation of the existing cranes have attracted wide attention of engineers and technicians. The design verification and safety evaluation of bridge crane structure are urgent problems to be studied in crane engineering field of our country. In this paper, the allowable stress method is used to verify and analyze the design of metal structure of bridge crane in terms of strength, stiffness and stability. On the basis of this, a Bayesian network theory is proposed to evaluate the current situation of bridge crane structure. In this paper, according to the development platform of Visual C and the powerful database storage ability of Access, a general bridge crane structure verification system based on allowable stress method is developed in this paper. Starting with the factors affecting the safety of the metal structure of the bridge crane, this paper analyzes the causes of accidents and the potential factors of insecurity in the structure of the bridge crane at present, and considers the strength and stiffness comprehensively. The influence of stability and other external factors on the structural safety of overhead crane is analyzed in detail. According to the causality within the crane, a practical evaluation index system for structural safety of bridge crane is established. The Bayesian network is introduced to evaluate the security of the network, and the network node and its range are determined. The topological structure of the Bayesian network is established, and the conditional probability distribution of the node is determined. Finally, the Bayesian network evaluation model of bridge crane structure safety is constructed. The simulation results of GeNIe software show that it is feasible to use Bayesian network to evaluate the structure safety of bridge crane.
【学位授予单位】：太原科技大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH215

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