钢纤维高强混凝土三桩承台试验研究与有限元分析-水工结构工程专业论文.docxVIP

摘要摘 摘要 摘 要 桩基础具有承载力高、沉降量小而均匀和抗震性能好等特点，因此桩基础 的应用比较广泛。承台作为桩基础中承上启下的关键构件，提高其受力性能十 分重要。在桩基承台中应用纤维高强混凝土可提高其抗裂性能、抗剪性能、抗 震性能及耐久性，同时能减小承台厚度，为满足高层和超高层建筑对桩基承台 的要求提供了新的途径。本文通过试验研究和有限元分析，探讨了钢纤维高强 混凝土(SFHSC)三桩承台的受力性能和传力机理，主要内容如下： (1)通过对6个比例为1：5的钢纤维高强混凝土三桩承台试件进行模型试 验，研究了承台厚度和钢纤维体积率两个变化参数的影响，描述了承台的裂缝 开展和破坏形态。结果表明：三桩承台的破坏己不同于一般的受弯构件，属于 剪切或冲切破坏。 (2)综合本文试验结果和国内外相关研究成果，分析了钢纤维高强混凝土 三桩承台极限承载力的影响因素。影响钢纤维高强混凝土三桩承台极限承载力 的主要因素有：承台有效厚度、钢纤维体积率、混凝土强度、承台距厚比、配 筋量和配筋方式。同时，钢纤维类型也是影响承台极限承载力的一个重要因素。 (3)通过试验分析了三桩承台底部纵向钢筋的应力变化以及承台侧面混 凝土的应变特征。结果表明：底部纵向钢筋沿长度的应力变化很小，犹如一根 拉杆，说明三桩承台的受力性能类似于空间桁架模型；混凝土应变不再符合平 截面假定。三桩承台受力性能符合空间桁架模型。 (4)建立三桩承台的有限元模型，探讨了三桩承台的传力模型。结果表明： 三桩承台的传力模型符合空间桁架模型，承台的破坏是由于桩柱连线范围内的 钢纤维高强混凝土斜压杆发生剪切或劈拉破坏引起的。 关键词：钢纤维高强混凝土，三桩承台，试验研究，有限元分析 ABSTRACTABSTRACT ABSTRACT ABSTRACT Recently,pile foundation has been widely applied owing to its high bearing capacity,small and uniform settlement and good anti-seismic performance，in which the caps of pile form a connecting link between the upper structure and the down pile SO that it is the crucial bearing component of pile foundation．It is very important to improve the mechanical properties of caps．The steel fiber reinforced high strength concrete can improve the crack resistance，shear resistance，earthquake resistance and the durability of pile caps．Also，it can reduce the thickness of pile caps． Therefore the application of SFHSC provides a new way to meet the request of high—rise and high—rise building to pile caps．The mechanical properties and transfer model of SFHSC three—pile caps were discussed by experimental research and theoretical analysis in this paper，and the main contents are as follows： (1)Based on the experimental study on 6 specimens of SFHSC three—pile caps with the ratio of the model to the real of 1：5，the effects of two variable parameters including the thickness of the cap and the volume fraction of steel fiber were studied． The developing of cracks and failure of caps were described．The test results indicate that the destruction of thr