A Study on Impulsive Fracture of Steel Plates and Members Caused by the Shaped Charge during the Blasting Demolition of Steel Buildings

本研究的主要目的是建立聚能装药数量与钢板切割面积的关系，并开发1/3尺度h柱的切割方法。1999年选用了5种钢板（SS400、SM490、SA440B、HITEN690B、HITEN780B）进行聚能装药切割，得出了聚能装药用量与钢板切割面积的关系。在爆炸试验中使用高速摄像机，得出以下结论：1) Pentolite聚能药静爆速度约为7000m/s。2)钢板的切断不仅受到金属射流的作用，而且受到金属射流后的线刀效应的影响。2000年进行了1/3比例尺h柱切割爆破试验。测试了四种切割模式。它们是水平和倾斜的完整岩屑和两个部分岩屑（水平和l形），其中法兰仍未被切割。这些试验表明，根据1999年试验结果确定的聚能装药量可以成功地切割h柱，并且可以控制爆破拆除中结构的倒塌模式。

Main objectives of this research are establishment of the relation between the quantity of the shaped charge and cutting area of steel plate, and development of a cutting method of 1/3-scale H-columns.In 1999 five kinds of steel plates(SS400, SM490, SA440B, HITEN690B, HITEN780B)are selected and cut by the shaped charge, which give rise to the relation between the quantity of the shaped charge and cutting area of steel plates. During the explosive tests a high-speed camera is used and the following conclusions are derived. 1)Stationary explosive speed of the shaped charge using Pentolite is about 7000m/sec. 2)Steel plates are cut off not only by the effect of metal jet but also by the liner-cutter effect following the metal jet.In 2000 explosive tests of cutting 1/3-scale H-column are performed. Four cutting patterns are tested. They are horizontal and inclined complete cuttings and two partly-cuttings(horizontal and L-shaped)where a flange remains not to be cut. According to these tests it is concluded that the amount of shaped charge decided according to experimental results in 1999 brings successful cuttings of H-columns and that it is possible to control the collapse mode of the structures in the blasting demolitions.