DYNAMIC ANALYSIS OF TALL BUILDING USING REDUCED-ORDER CONTINUUM MODEL

On Oct. 17, 1989, a tall, steel-framed, San Francisco office building with 47 above-grade stories was excited by the Loma Prieta earthquake. The building response was recorded by accelerometers maintained by th e California Division of Mines and Geology Strong Motion Instrumentati on Program. From the records, important characteristics of the buildin g response can be identified. In this paper, a computationally efficie nt, approximate dynamic analysis of the building using a reduced-order continuum model is conducted. By making use of the repetitive nature of the lattice framing system, finite-element models generated using c ontinuum methodology have significantly fewer degrees of freedom than models generated using classical discrete finite-element techniques. T hese reduced-order models can therefore lead to significant savings in the computational effort and cost typically associated with dynamic a nalyses of large structures. The vibrational characteristics of the co ntinuum model, as well as the results of the dynamic analysis, are com pared to the building's recorded response. The continuum model is accu rate in capturing the dominant periods of vibration as well as the tim e-history response and shows promise as a tool for preliminary design of large lattice structures.