Numerical study of Ashiyahama residential building damage in the Kobe Earthquake

Studies are made on the structural damage at Ashiyahama residential high-ri se steel building complex due to the Hyogo-ken Nanbu Earthquake (Kobe Earth quake), which occurred on 17 January 1995. The axial breakage of very thick -plated steel columns of the mega-structure is unprecedented and has been a ttracting the special attention of structural engineers. The cause of the d amage is first investigated from numerical computation with recourse to an explicit method of dynamic analysis based on a continuous medium. The numer ical result is compared with that obtained from a conventional multi-mass l umped stiffness model combined with an equivalent lateral-force procedure. By comparing both the numerical results, the latter conventional method is shown to be inadequate for achieving earthquake-resistant capability. The d estructive power of the ground motion is found to have exceeded the horizon tal earthquake-resistant capacity that is prescribed in the structural desi gn criteria. Great axial stresses are produced in columns by combined actio n of bending moment and axial force due to over-turning moment. The fractur e of heavy steel columns is caused from only the horizontal component of se ismic ground motion. Actual locations of significant damage are closely rel ated to the occurrence of plastic hinges in the analysis. It is emphasized as a warning to avoid yielding concentration in particular storeys. Lastly, recommendations to enhance earthquake-resistant design are proposed from a practical point of view. Copyright (C) 2001 John Wiley & Sons, Ltd.