Seismic drift response of building structures in seismically active and near -fault regions

The main goal of this study is the development of a simple procedure for the assessment of seismic drift response of building structures located in seismically active and near-fault regions. The displacement-based design approach which correlates observed damage of a structure according to its drift ratio will be the reference point. The concept of ground velocity change, ΔV and its effects on the nonlinear displacement response of building structures are investigated. Ten ground motion data obtained from recording stations located in one of the most seismically active regions in the world, Turkey where two consecutive earthquakes occurred within three months in 1999 are used. The results of the nonlinear displacement response of the building structures revealed that for ΔV \u3e 0.75 m/s and [special characters omitted] \u3c 1.0 the displacement demand exceeds the displacement spectrum defined by Lepage (1997). In general, it is observed that the increase in ΔV increases the nonlinear displacement demand and the observed damage accordingly. To avoid excessive displacement demand an increase in base shear strength is beneficial to the performance of the building. Nonlinear displacement spectra are defined for single-degree-of-freedom systems and a three-dimensional displacement response spectrum for Earthquake-Resistant Design in Turkey is developed. Eight five-story reinforced concrete buildings are proposed which are proportioned to reflect the common construction practice in Turkey. Their behavior is investigated assuming that these buildings act as multi-degree-of-freedom systems. A relationship between the nonlinear displacement spectra of MDOF systems and SDOF systems is defined. A set of four buildings located close to a recording station were previously investigated (Engvall 2002) to determine the correlation between the calculated nonlinear behavior of the building structures and their observed damage. It revealed that a nonlinear SDOF system represented best the behavior of a building during an earthquake excitation. This station recorded the ground motions at the town of Duzce which was destructed during both earthquakes. In the light of the described findings it is concluded that the proposed methodology regarding the effect of ground velocity change on the maximum drift of the building structures represents the observed behavior of the building structures located in seismically active regions well