L形型钢混凝土异形柱火灾后力学性能的试验研究

发布时间：2018-03-23 09:10

  本文选题：L形异形柱　切入点：火灾后　出处：《青岛理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：型钢混凝土异形柱除配置有型钢外，还含有适量箍筋，其承载力和抗震性能得到明显提高，轴压比限值也可适当放宽。当前国内外对型钢混凝土异形柱的研究主要集中于常温情况下，，而对抗火性能的研究几乎处于空白阶段，且尚未形成一套系统的计算理论和设计方法。通过对L形型钢混凝土异形柱火灾后力学性能的研究，不仅为其火灾后损伤评估及修复加固工作提供依据，也可更好的完善我国抗火设计理论及相应规程。全文从试验研究、数值模拟、截面特性三个方面进行系统研究，其主要工作和结论包括以下四个方面： 1．对8根L形型钢混凝土异形柱进行ISO834标准升温曲线下两面受火试验，测得截面温度场分布、轴向和侧向位移、考察试件火灾后表面裂缝分布规律。结果表明：(1)炉温曲线与ISO834标准升温曲线基本吻合；(2)测点温度随着距受火面距离减小而逐渐增高，最高温度达到500℃，15min~20min时间段内曲线较为平缓，尔后升温逐渐加快；(3)轴向位移最大值约6mm，最小值仅为1.1mm。 2．进行常温下静力加载试验，测得其火灾后极限承载力、混凝土和型钢各自应变、轴向和侧向位移，以及柱中截面处混凝土与型钢之间的粘结滑移，并观察破坏现象。结果表明：(1)异形柱受压过程可分为弹性、带裂缝工作和破坏三个阶段；(2)当偏心距为60mm、100mm、180mm、240mm时，沿45°加载试件相对于0°加载，极限承载力分别降低了20.3％、20.8％、35.2％和38.1％；(3)忽略加载初期及末期产生的轴向位移值，基本维持在（10±2）mm范围内，混凝土和型钢之间粘结滑移小于2mm。 3．采用有限元软件ABAQUS进行温度场分析及损伤后结构分析，得到截面温度场分布、极限承载力、变形及应变计算结果。结果表明：(1)截面温度场变化规律与试验结果基本一致；(2)柱1~柱9极限承载力计算结果与试验结果误差分别为7.7％、0.57％、11.2％、15.17％、15.08％、7.3％、9.9％、8.06％和13.5％；(3)轴向位移与侧向位移曲线变化规律基本相似，沿0°加载时， Y轴方向最大侧移约为X轴方向的1/2。 4．通过试验与计算结果，分析广义中性轴位置、截面平均应变、Nu-e曲线及Nu-Mu相关曲线，进一步揭示其火灾后的力学性能，此外，通过数值计算评估其在不同受火时间后的截面损伤。结果表明：(1)从平均应变意义上讲，平截面假定对火灾后L形型钢混凝土异形柱仍然适用；(2)由Nu-Mu相关曲线可以看出，0°加载时得到的相关曲线与坐标轴之间的包络面积与45°加载相比较大；(3)严重损伤区域边界在截面内类似于“圆弧形”，试件受火1h、1.5h、2h、3h后损伤深度分别为30mm、36mm、46mm和65mm，占整个截面面积的17.68％、20.05％、25.75％和36.91％。
[Abstract]:In addition to the profile steel, the special-shaped steel reinforced concrete column also contains a suitable amount of stirrups, and its bearing capacity and seismic performance are obviously improved. The limit of axial compression ratio can also be relaxed. At present, the research on SRC special-shaped columns at home and abroad is mainly focused on the normal temperature, but the research on fire resistance is almost blank. And a set of systematic calculation theory and design method have not been formed. Through the study of mechanical properties of L-shaped steel reinforced concrete special-shaped columns after fire, it not only provides the basis for damage assessment and repair and reinforcement work after fire. It can also better improve the fire design theory and the corresponding rules. This paper studies systematically from three aspects: experimental research, numerical simulation and cross-section characteristics. The main work and conclusions include the following four aspects:. 1. Eight L-shaped steel reinforced concrete special-shaped columns were subjected to fire test under ISO834 standard heating curve. The temperature field distribution, axial displacement and lateral displacement of the section were measured. The distribution of surface cracks in specimens after fire is investigated. The results show that the temperature curve of the furnace agrees with the ISO834 standard temperature curve basically. (2) the temperature of the measuring point increases with the decrease of the distance from the fire surface. The maximum temperature of 500 鈩

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