Failure Mechanism of Concrete Pile

桩基支撑钢筋混凝土建筑抗震性能分析在进行结构计算时，通常将建筑物分为地上部分和地下部分。正如已经提到的，审查地下部分的最终强度并不是法律义务。因此，地下部分的最终强度是未知的。因此，由于1995年日本南部地震，许多钢筋混凝土建筑物在地下部分遭到破坏，而地上部分却没有受到破坏。为了模拟轴力和弯矩之间的相互作用，本文引入了多弹簧模型。对一幢7层钢筋混凝土建筑进行了分析。起初，我们只分析了这座建筑的地上部分。屈服几乎发生在梁的末端。这是一种理想的铰链机构。其次是地上部分和地下…更多的部分被作为一个整体进行分析。在梁到达屈服曲率之前的早期阶段，桩顶已发生屈服。这与地震造成的破坏是一致的。预制高强混凝土桩的抗剪强度这是分析结果与试验最大抗剪强度的比较。横轴表示轴向应力、预应力和外部轴向应力的总和。当轴向应力之和较小时，分析结果大于实验结果。该公式是Shibata和Joh为了计算方形截面柱的极限抗剪强度而提出的。我们将该方程应用于圆柱形截面桩。轴向应力之和越大，安全系数越低。我们研究了桩在桩顶开始屈服之前通过剪切破坏的可能性。在大多数情况下，当桩顶开始屈服时，桩的抗剪强度小于抗剪强度。日本目前使用的PHC桩容易产生剪切破坏。较少

Analysis on the Seismic Behavior of Reinforced Concrete Building supported by PileIn making structural calculation, a building is commonly divided into two parts, aboveground part and underground part. As already mentioned, it is not legal obligation to examine the ultimate strength for the underground part. So, the ultimate strength of the underground part was left unknown. Therefore, many reinforced concrete buildings were damaged at the underground part due to the 1995 Hyougoken Nanbu Earthquake without damage of aboveground part.Here, we analyzed the damage considering the interdependence of aboveground part and pile. In order to simulate the interaction between axial force and bending moment, the multi spring model is introduced here. A 7 storied reinforced concrete building is analyzed. At first, we analyzed only the aboveground part of this building, alone. Yielding has occurred at the end of almost beams. This is ideal hinge mechanism. Next the aboveground part and underground … More part are analyzed together as a body. The yielding has occurred at the top of pile in the early stage before beams reach at the yield curvature. This agreed with the damage due to the earthquake.Shear Strength of Pre-cast High Strength Concrete PileThis is the comparison between analytical result and experimental maximum shear strength. The horizontal axis shows the sum of the axial stresses, pre-stress and external axial stress. When the sum of axial stresses is low, the analytical results are larger than the experimental one. The equation was proposed by Shibata and Joh in order to calculate the ultimate shear strength of column with square section. We apply this equation to the pile with cylindrical section. The higher the sum of axial stresses becomes, the lower the factor of safety is. We examine the possibility that the pile fails by shear before the yielding has begun at the top of pile. In almost cases, the shear strength is smaller than the shear force when yielding has begun at the top of pile. The PHC pile now in use in Japan tends to cause the shear failure. Less