【作者】 刘发起；

【导师】 杨华；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2010， 硕士

【摘要】 钢管混凝土以其承载力高、塑性韧性好、施工方便及抗火性能好等优点,在多、高层建筑中得到了广泛的应用。矩形钢管混凝土柱作为钢管混凝土结构的一种重要的构件形式,除兼具上述优点外,还因其抗弯刚度大、节点构造简单而备受结构工程师的青睐。结构的抗火性能是决定结构能否安全工作的重要因素之一,现行钢管混凝土结构的抗火规范或规程,如《矩形钢管混凝土结构技术规程》(CECS159:2004)和《钢管混凝土结构技术规程》(DBJ13-51-2003)等,均假设钢管混凝土柱承受四面火灾作用,而实际结构中由于墙体的阻隔作用,框架柱除可能承受四面均匀火灾作用之外,尚可能遭遇三面火灾作用。由于非对称的温度分布,构件截面材料的劣化程度也非对称,导致截面材料的强度中心发生偏移,从而形成附加的偏心距;此外,非对称的温度分布导致柱子受火面膨胀变形大,背火面膨胀变形小,从而产生向受火面挠曲的附加变形。综上所述,矩形钢管混凝土柱三面受火与四面受火存在诸多差异,有必要对三面受火矩形钢管混凝土柱的抗火性能进行研究。据此,本文对三面受火的矩形钢管混凝土柱进行了试验研究和有限元分析,具体包括以下三部分内容:(1)三面受火的矩形钢管混凝土柱试验研究和分析进行了2根三面受火1根四面受火的矩形钢管混凝土柱足尺抗火试验,实测了受火全过程中构件的截面关键位置的温度、轴向变形和侧向挠曲,获得了三面受火的矩形钢管混凝土柱的破坏模式,基于试验数据,分析了荷载比和受火边界对耐火极限的影响规律。(2)三面受火的矩形钢管混凝土柱有限元分析基于ABAQUS建立了可用于分析三面受火的矩形钢管混凝土柱温度场和抗火性能的三维有限元分析模型,并得到了相关试验验证。进而对三面受火的矩形钢管混凝土柱的受力机理进行了深入研究,包括矩形钢管混凝土柱的温度分布、破坏模式、应力应变的分布以及发展等。(3)三面受火的矩形钢管混凝土柱抗火性能的参数分析进行了三面受火的矩形钢管混凝土柱抗火性能的参数分析,包括升温时间、截面尺寸、含钢率、保护层厚度和截面高宽比对温度场的影响规律;荷载比、截面周长、长细比、含钢率、钢材强度、混凝土抗压强度、荷载偏心率、截面高宽比和保护层厚度对耐火极限的影响规律;提出了可考虑不同背火边界的三面受火矩形钢管混凝土柱耐火极限的简化计算公式,以期为工程应用提供参考。更多还原

【Abstract】 Concrete filled steel tubular (CFST) columns have gained wide applicatioin in multi-storey and high-rise buildings for their advantages of high load carrying capacity, good ductility, flexibility of construction and high fire resistance. As one form of CFST columns, Rectangular Hollow Section (RHS) columns acquire more attention for their high flexural rigidity, simple construction of joint besides advantages metioned above. Fire resistance is one of the most important factors affecting building safety, current criterions and specifications in operation, CECS159:2004 and DBJ13-51-2003, etc. assume CFST columns being exposed to fire uniformly. But in fact, because of the barrier effect of adjacent walls, columns maybe under three-surface fire loading, which would result in asymmetry thermal field and then form additional eccentricity owning to offset of section material strength center. In addition, asymmetry thermal field causes dilatational strain of surface exposed to fire is greater than that not exposed to fire, which arouses additional dilatational strain. It’s therefore significant need to investigate RHS columns under three-surface fire loading based on previous research on those under four-surface fire loading. Experimental research and finite element analysis are carried out for RHS columns under three-surface fire loading, includeing:(1) Experimental research of RHS columns under three-surface fire loadingThree full-scale RHS columns, including one column subjected to four-surface fire loading and the others three-surface fire loading, were tested, thermal field of cross section, axial deformation and lateral deformation were measured. The failure mode of the columns was obtained and the affection of load level and fire boundaries to fire resistance was analysed.(2) Finite element analysis of RHS columns under three-surface fire loadingThree-dimensional FEM model was developed using ABAQUS to analyze thermal field and fire resisrance of RHS columns and the results were validated by the experimental results. Then the mechanism of RHS columns under three surface fire loading and sustained load was researched, including thermal field, failure mode, distribution of stress, strain and evolution, etc.(3) Parametric studies of RHS columns under three-surface fire loadingParameters were studied to investigate their influence on thermal field and fire resistance, including the influence of exposure time, dimension of cross-secition, steel ratio, thickness of fire proof and depth to width ratio on thermal field; the influence of load level, dimension of cross-section, slenderness ratio, steel ratio, strength of steel and concrete, load eccentricity, depth to width ratio and thickness of fire proof on fire resistance, summarize the rules of their affection. A simple equation was put forward for predictinig the fire resistance of RHS columns under three-surface fire loading, which may provide a reference for engineering applications.更多还原