Explosive demolition planning of building structures using key element index
Daigoro ISOBE, Ranmeng Jiang
Abstract
A systematic and appropriate selection of columns to be removed should be conducted to ensure the safe and reliable demolition of old or uninhabitable buildings. However, the explosive demolition techniques used at present mostly rely on experiences and know-how built up by predecessors and are not fully open to general users. Therefore, a clear selection criterion for columns to be removed should be developed based on a quantitative value that indicates the contribution of each column in a building structure. This study applied a key element index to evaluate the contribution of columns and their variance to multistage explosive demolition planning. An adaptively shifted integration (ASI)-Gauss code was used to simulate and investigate the explosive demolition sequences of a 10-story steel-framed building. Various timings between the multistage blasts were evaluated by comparing the efficiencies and levels of safety during demolition. By removing the groups of columns from those that had a greater influence on the variance of the key element index values, a large difference was obtained in the distribution of the index values, especially in the lower structure. The results showed that if a building is not too weakened in the initial blast, the 2nd blast of the main blasts should be conducted at the moment of impact between the upper and lower structures or the following short time to make the most of the impact. The results also showed that too much weakening of a building at the preceding stage might not provide full advantage of the impact that occurs between the main blasts.