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，由于预计在不久的将来发生的东海、东南海或南开地震等破坏性深海地震造成的大功率、长周期分量的地震地面运动将持续几分钟。本研究旨在明确钢结构高层建筑在遭受强震时估计的长周期地震动的情况下的临界性能。在大多数情况下，钢结构框架的抗震性能受到梁倒塌的限制。在本研究中，为了明确梁的行为及其临界性能，采用与现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循环加载试验。总共使用了30个标本，涵盖8种不同类型。为了更清楚地了解加载滞后对吸能能力的影响，对相同形状的试件进行了几种不同幅值和循环模式的加载。研究结果总结如下：对于以梁端连接处法兰断裂决定最大强度的梁的临界性能：1)断裂行为可分为以下两种类型。型（F1）：裂纹从法兰焊缝宽度中心扩展后试样断裂，截面积比减小到70 ~ 80%。（F2）型：试件从法兰焊缝宽度边缘扩展后发生断裂，截面积比减小至90 - 95%。2)循环加载时的最大强度比随塑性循环加载次数的增加而减小。但（F2）型的下降幅度小于（F1）型。(3)单调加载情况下的最大强度比可用现有方法估算。(4)单调荷载下的能量吸收能力可以用单调荷载下的最大强度比来估算。5)推导了利用单调荷载的能量吸收能力和循环荷载的有效次数估算循环荷载下能量吸收能力最低限值的方法。关于由局部屈曲决定最大强度的梁的临界性能1)单调荷载情况下的能量吸收能力可用现有参考文献中规定的方法估计。2)推导了利用单调荷载的能量吸收能力和循环荷载的有效次数估算循环荷载下能量吸收能力最低限值的方法。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