Abstract
The technology used in the demolition of buildings has always been a major
interest in the civil engineering field. Conventional demolition techniques
using hydraulic concrete crusher, concrete cutter or non-explosive demolition
agent requires a longer period of work and higher cost. A demolition technique
by controlled explosion using high explosives has developed in recent years.
In Japan, the explosive demolition technique has recently been used only
in a few demolition cases, such as on the buildings of the international
exhibition in Tsukuba or a vacant hotel in Kyoto. The explosive demolition
has a high risk of damaging other neighboring buildings especially in urban
areas, even though it increases work efficiency. Therefore, the pre-assumption
by computational analysis has become an essential matter in the process.
The Great Hanshin Earthquake, which occurred in January 1995, damaged a
wide area. The structural design guidelines for buildings especially against
vertical seismic wave has been thoroughly reconsidered. Therefore, the
arrival of a convenient technique to analyse collapse modes of structure
objects under 3 axes of excitation, is now desired.
However, generally used finite element code needs some extra complicated
processes to simulate these kinds of dynamic collapse problems which contain
strong nonlinearity and discontinuity, such as fracture occurred in flexural
damage or shear damage in reinforced concrete members.
The Adaptively Shifted Integration (ASI) technique, which produces the highest computational efficiency in the finite element analyses of framed structures including static and dynamic collapse problems, is applied to the explosive demolition analysis and the seismic damage analysis of a reinforced concrete building. By expressing an explosion or a fracture by a plastic hinge located at the exact position with a simultaneous release of resultant forces on the element, discontinuous problems such as these dynamic collapse problems can be easily analysed even by the finite element code with the displacemental form. By using the algorithms described in this paper, sufficiently reliable solutions for the practical use have been obtained in the explosive demolition and seismic damage analyses of a 5 stories-5 span reinforced concrete building. The present technique can be easily implemented with a minimum effort into the existing finite element codes utilizing the linear Timoshenko beam element.