On the Characteristics of Vertical Ground Motions Induced by
Earthquakes and the Seismic Provisions regarding Vertical Ground Motions in
Each Building Code of Japan, China and U.S.A.
By T. Shimazu
Concrete Journal, Vol.43, No.11, Nov. 2005
- Synopsis
- First, this paper explains the characteristics of vertical ground motions, mainly based on the recorded data obtained during 1994 Northridge earthquake. Ratios of peak vertical to horizontal ground motions are discussed together with illustrated accelerograms and spectral acceleration of vertical ground motions. Ratios of peak vertical to horizontal acceleration at roof of buildings are also disucussed with the illustration of behaviors of parking concrete buildings during 1994 Northridge earthquake. Second, the seismic provisions regarding vertical ground motions in each building code of Japan, China and U.S.A are intruduced. In the Japan building code, no special provisions are provided exept the precast beams of PC building structures. In China, special provisions are given for high-rise buildings (more than 9 storied buildings) calculated based on spectral acceleration and the distribution of inverted triangle as well as for large span beams. In U.S.A., special provisions are given for strength design method, taking into considerations the effects of vertical ground motions on load factors. Finally, suggestions are given for design methods regarding vertical ground motions induced by big earthquakes in the near future.
- Keywords:
- recorded data on ground motions, response spectra, response of buildings, large span beams, tall buildings, load combinations, natural period
