工业建筑钢结构疲劳测试、评估及加固研究

发布时间：2018-04-24 02:19

本文选题：工业建筑 + 钢结构　；参考：《天津大学》2014年博士论文

【摘要】：对钢结构而言，以突然发生为特点的疲劳破坏对结构安全危害很大。工业建筑所处环境恶劣、负荷大且承受重复动载，出现事故的几率更大，尤其是钢吊车梁不断出现未达到设计使用年限就发生开裂甚至断裂，以及一些间接承受动力荷载或理论上不出现拉应力构件如钢柱吊车肢柱头等出现疲劳破坏的工程实例，极大地影响着工业建筑结构安全。本文以线性累积损伤原理为理论基础，以炼钢厂原料跨、接受跨和机械水压机车间为工程背景，测试分析不同车间吊车梁的欠载效应等效系数，重点针对实腹式吊车梁上翼缘与腹板连接处、变截面吊车梁梁端、吊车肢柱头等开展结构损伤检查、动静态测试、结构有限元计算分析等工作，分析疲劳开裂出现的原因，探讨不同疲劳评估方法的运用，研究不同结构加固方式并进行优化选择，形成成套实用的工业建筑钢结构疲劳评估和加固技术。 1、对不同生产性质和天车的车间开展疲劳问题普查、分类，根据不同类型疲劳问题的危险程度，选择实腹式吊车梁上翼缘与腹板连接处、变截面吊车梁的梁端、吊车肢柱头等三部位展开重点研究。 2、针对十一个炼钢原料跨和接受跨、机械水压机厂房的十八根吊车梁开展应力测试，推算吊车梁以2×106次疲劳强度为基准的欠载效应等效系数，推算值比我国规范推荐值普遍偏大，给出了规范调整欠载效应等效系数取值的建议。 3、对实腹式钢吊车梁上翼缘附近开展疲劳研究，将轨道和吊车梁作为一个体系开展有限元计算，以接触单元模拟轨道和吊车梁之间的相互作用，展示了轨道偏心作用下该部位复杂的应力状态；采用有限元计算结果，首次依据德国规范对上翼缘附近进行了基于剪应力和正应力的疲劳评估，为我国规范增加相关疲劳评估的内容提供了工程验证。 4、结合现场测试、有限元计算分析吊车肢柱头的开裂原因，，对钢柱吊车肢柱头提出多种加固方案并进行优化选择；首次以实测数据为基础对吊车肢柱头开展了疲劳可靠性评估。 5、通过有限元计算确定不同形式直角突变式吊车梁端部应力集中部位和程度，首次基于Verity理论对疲劳裂纹扩展驱动能理论进行改进，推导出对网格划分、单元类型不敏感的裂纹扩展驱动能计算公式，对直封板和角钢封板形式的直角突变式吊车梁端部开展疲劳性能评估，验证了角钢封板直角突变式吊车梁相对于直封板吊车梁的优越性，提出多种加固方案并对加固效果进行计算验证。
[Abstract]:For steel structures, fatigue failure characterized by sudden occurrence is very harmful to structural safety. Industrial buildings are in a harsh environment, with heavy loads and repeated dynamic loads, and there is a greater chance of accidents, especially when steel crane beams continue to crack or even break if they do not reach their design life. Some engineering examples of fatigue failure such as steel column crane column head and so on which are indirectly subjected to dynamic load or without tensile stress in theory have greatly affected the safety of industrial building structure. Based on the principle of linear cumulative damage, the equivalent coefficient of underloading effect of crane beams in different workshops is tested and analyzed in this paper, based on the engineering background of material span, acceptance span and mechanical hydraulic press workshop of steelmaking plant. Focusing on the joint of the upper flange and web of the solid web crane beam, the end of the variable section crane beam, the head of the crane limb and column, etc., the structural damage inspection, dynamic and static test, structural finite element analysis and so on are carried out to analyze the causes of fatigue cracking. This paper discusses the application of different fatigue assessment methods, studies and optimizes the strengthening methods of different structures, and forms a complete set of practical fatigue assessment and reinforcement techniques for steel structures of industrial buildings. 1. Carrying out a general survey and classification of fatigue problems in workshops with different production properties and cranes. According to the dangerous degree of different types of fatigue problems, the joint of the upper flange and web plate of the full web crane beam and the beam end of the variable section crane beam are selected. Three parts, such as the pillar head of crane limb, are studied emphatically. 2. For eleven steel raw materials span and acceptance span, eighteen crane beams of mechanical hydraulic press workshop are tested, and the equivalent coefficient of underload effect of crane beam based on 2 脳 106 fatigue strength is calculated. The calculated value is generally larger than the recommended value of our country's code, and the suggestion of adjusting the equivalent coefficient of underloading effect is given. 3. The fatigue research is carried out near the upper flange of the solid web steel crane beam. The track and crane beam are taken as a system to be calculated by finite element method, and the interaction between track and crane beam is simulated by contact element. The complex stress state of this part under eccentric action of track is shown, and the fatigue assessment based on shear stress and normal stress near the upper flange is carried out for the first time according to German code, using finite element calculation results. It provides engineering verification for increasing the content of fatigue assessment in the code of our country. 4. According to the field test, finite element method is used to analyze the cracking reason of the column head of the crane, and a variety of reinforcement schemes are put forward and the optimum selection is carried out. The fatigue reliability of the column head of the crane limb is evaluated for the first time on the basis of the measured data. 5. Through the finite element calculation, the stress concentration position and the degree of stress concentration at the end of the crane beam with different forms of right angle mutation are determined, and the fatigue crack propagation driving energy theory is improved based on the Verity theory for the first time, and the mesh division is derived. The formula for calculating the driving energy of crack propagation, which is insensitive to the element type, is used to evaluate the fatigue performance of the straight seal plate and the angle steel seal plate in the end of the right angle mutant crane beam. The superiority of angle steel seal plate right angle mutant crane beam compared with that of straight seal plate crane beam is verified. Several reinforcement schemes are put forward and the effect of reinforcement is verified by calculation.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU391

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