A study on the ultimate performance of steel high-rise buildings subjected to long period seismic ground motions which are estimated during severe earthquakes

据推测，在东京都、大阪和名古屋地区，由预计将在不久的将来发生的东海、东海或南开等破坏性深海地震所引起的大功率长周期地震动将持续数分钟以上。本研究旨在明确钢结构高层建筑在强震过程中估计的长周期地震动作用下的临界性能。钢结构框架的抗震性能在大多数情况下都受到梁的倒塌的限制。为了弄清梁的受力性能及其临界性能，采用与既有高层框架相同的宽厚比和端部连接细节的梁试件进行了反复荷载试验。总共使用了30个样本进行测试，涵盖8种不同的类型。对于Purp…更多的是为了弄清加载滞后对能量吸收能力的影响，对具有相同形状的试件进行了不同幅值和不同循环模式的加载试验。研究结果表明：对于梁的临界性能而言，梁的最大强度取决于梁端连接处翼缘的断裂。1)断裂行为可分为以下两种类型。类型(F1)：裂纹后的试件断裂从翼缘宽度的中心扩展，截面积比下降到7080%。类型(F2)：裂纹后的试件断裂从翼缘边缘扩展翼缘焊缝宽度和截面积比减小到90~95%。2)随着塑性循环次数的增加，循环荷载作用下的最大强度比减小。然而，3)单调加载情况下的最大强度比可以用现有的方法估计。4)单调加载情况下的能量吸收能力可以用单调加载情况下的最大强度比来估计。5)提出了一种利用单调加载的能量吸收能力和循环加载的有效次数来估计循环加载下的能量吸收能力下限值的方法对于由局部屈曲确定最大强度的梁，1)单调加载情况下的吸能能力可以用现有文献中的方法估计。2)推导出一种同时使用单调加载的能量吸收能力和循环加载的有效次数来估计循环加载情况下的能量吸收能力下限值的方法。较少

It is conjectured that in the Tokyo Metropolitan, Osaka and Nagoya areas seismic ground motions with large power over a long period component caused by destructive deep-sea earthquakes such as Tokai, Tonankai or Nankai earthquakes, which are expected to occur in the near future, will continue over several minutes. This study aims at making clear the critical performance of steel high-rise buildings in cases where they are subjected to long period seismic ground motions which are estimated during severe earthquakes.The seismic performance of steel structural frames is limited by the collapse of beams in most cases. In this study, in order to make clear the behavior of beams and their critical performance cyclic loading tests were carried out using beam specimens with about the same width-thickness ratio as well as with the same end connection details as those which are used in existing high-rise frames. In all, 30 specimens were used in the tests covering 8 different types. For the purp … More ose of making clear the effects of the loading hysteresis on the energy absorption capacity, several types of loadings each with different amplitudes and cyclic patterns were carried out for the specimens which have the same shapes.The results obtained from this study can be summarized as follows :With regard to the critical performance of beams whose maximum strength is determined by the fracture of flanges at the beam end connection1)The fracture behavior can be divided into the following two types.Type (F1): The specimen fractures after cracks expand from the center of the width of the flange weld and the sectional area ratio decreases to 70 80%.Type (F2) : The specimen fractures after cracks expand from the edge of the width of the flange weld and the sectional area ratio decreases to 90 95%.2)The maximum strength ratio in the case of the cyclic loading decreases with an increase in the number of the plastic cyclic loading. However, the decreasing degree in the case of type (F2) is smaller than that for (F1).3)The maximum strength ratio in the case of the monotonic loading can be estimated using the existing method.4)The energy absorption capacity in the case of the monotonic loading can be estimated using the maximum strength ratio in the case of the monotonic loading.5)A method for estimating the lowest limit value of the energy absorption capacity in the case of the cyclic loading using both the energy absorption capacity for the monotonic loading and the effective number of the cyclic loading has been derived.With regard to the critical performance of beams in which the maximum strength is determined by the local buckling1)The energy absorption capacity in the case of the monotonic loading can be estimated using the method prescribed in the existing reference.2)A method for estimating the lowest limit value of the energy absorption capacity in the case of the cyclic loading using both the energy absorption capacity for the monotonic loading and the effective number of the cyclic loading has been derived. Less