【作者】 邱枫；

【导师】 王化杰；

【作者基本信息】 哈尔滨工业大学 ， 土木工程， 2019， 硕士

【摘要】 随着近三十年来国民经济的高速发展,具有良好性能的钢结构越来越多的在建筑领域得到了广泛的应用,近年来一大批改革开放初期建设的大跨空间钢结构建筑逐渐步入了其设计使用年限的后期,其耐久性问题有必要得到足够的重视,而腐蚀是影响钢结构耐久的一个重要因素,因此研究腐蚀后钢结构力学性能具有非常关键的意义,焊接空心球节点作为空间网架结构中广泛应用的一种节点形式,目前对于其腐蚀后受力性能研究很少,为了对空心球节点网架及相似结构的安全性能及使用寿命评估提供参考,本文对腐蚀后焊接空心球节点抗压力学性能进行一定研究,主要包括以下四部分内容:1.钢表面腐蚀后坑蚀形貌分布研究为研究钢表面凹凸不平的蚀坑现象对空心球节点应力分布及承载力退化的影响,本文分别对自然腐蚀、游泳馆潮湿环境下腐蚀以及通电加速腐蚀等三种腐蚀模式下的Q235钢表面坑蚀现象进行充分调研,运用光学数码显微镜以微米为单位对各腐蚀模式下的钢表面蚀坑分布进行几何测量,总结并建立这三种典型环境腐蚀模式下钢表面蚀坑几何尺寸的概率分析模型。2.受腐蚀影响的焊接球节点模型建立基于《JGJ7-2010空间网格结构技术规程》对常用空心球节点进行了尺寸设计,并基于ANSYS有限元平台,建立了可以考虑焊接残余应力和构件初弯曲影响的焊接空心球节点精细化有限元模型,并提出了高效的蚀坑模拟方法,为类似节点腐蚀后力学性能分析提供了方法支持。3.坑蚀现象对节点力学性能影响研究分析中是否应该考虑局部蚀坑的影响是钢结构腐蚀分析的关键问题,为考察钢表面坑蚀分布对空心球节点受压力学性能的影响,以自然环境、游泳馆潮湿环境以及通电加速腐蚀环境下的不同尺寸空心球节点为对象,对其进行了不同蚀坑分布范围、不同蚀坑深度的下的力学性能分析,得到了腐蚀中蚀坑设置对节点承载力的影响规律。4.局部腐蚀球节点承载力退化研究采用所建立的腐蚀节点精细化有限元模型,以腐蚀位置、腐蚀形状以及腐蚀深度为指标,对局部腐蚀后的焊接空心球节点承载力退化进行参数分析,探究各关键腐蚀参数对节点承载力退化的影响规律,在此基础上,给出了可以考虑腐蚀位置、腐蚀形状、腐蚀深度以及坑蚀影响的焊接空心球节点腐蚀后承载力退化率计算公式,为类似结构节点设计提供了技术参考。更多还原

【Abstract】 With the rapid development of national economy in the past 30 years,steel structures with good performance have been widely used in the construction field,In recent years,a large number of large-span space steel structure buildings constructed in the initial stage of the reformation and opening have gradually entered the later stage of their design working life.Therefore,it is necessary to pay enough attention to their durability.And corrosion is an important factor affecting the durability of steel structures,so it is of great significance to study the mechanical properties of steel structures after corrosion.As one of the widely used joints in space grid structure,there are few researches on welded hollow ball joints’ mechanical properties after corrosion at present.In order to provide a reference for the safety performance and service life evaluation of the hollow ball joint grid frame and similar structures,this paper studies the pressure-resistant performance of welded hollow ball joints after corrosion,mainly including the following four parts:1.Study on pit corrosion morphology distribution of steel surfaceIn order to study the effect of the pitting phenomenon on the steel surface on the stress distribution and bearing capacity degradation of hollow ball joints,this paper conducted a full investigation on the pitting phenomenon on the surface of Q235 steel under three corrosion modes,namely natural corrosion,corrosion in the wet environment of the swimming pool and accelerated corrosion by electrification.We used optical digital microscope to geometrically measure the distribution of corrosion pits on steel surface under various corrosion modes,summarized and established the probability analysis model of the geometric size of corrosion pits on steel surface under these three typical environmental corrosion modes.2.Establishment of welding ball joint model affected by corrosionBased on "Technical specification for space frame structures" size for common hollow ball node design,and based on the ANSYS platform,The study establishes welding hollow ball joint model considering the influence of welding residual stress and initial bending component,and proposes the effective corrosion pit simulation method,which offers method for the analysis of similar joints after corrosion.3.Study on the influence of pit corrosion on mechanical properties of jointsAnalysis should consider the effect of local corrosion pit or not is the key to the analysis of steel structure after corrosion.In order to explore the influence of pit corrosion distribution on the mechanical properties of hollow ball joints under compression in detail,this paper analyzes the parameters of the ring range,depth and size effect of corrosion on hollow ball joints with pit corrosion distribution under three typical corrosion environments,namely natural environment,wet environment of swimming pool and electrified accelerated corrosion environment,and obtains the influence of pit setting on the bearing capacity of the joint.4.Study on bearing capacity degradation of locally corroded ball jointsBased on the refined finite element model of the corroded joint,the corrosion position,the corrosion shape and the corrosion depth are taken as the indexes to analyze the parameters of the weld hollow ball joint after local corrosion so as to explore the influence law of each key corrosion parameter on the joint bearing capacity degradation.A formula for calculating the bearing capacity degradation rate of welded hollow ball joints after corrosion is given on this basis,which can take the influence of corrosion location,shape,depth and pit corrosion into consideration,and provides technical reference for similar structure joint design.更多还原