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Effect of vertical ground motion on the performance of high-rise buildings

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2020
Keskin, Engi
Throughout the history, the creation of new environments to support the needs of urban populations has been attained to a great extent through horizontal construction. When settlements with limited territories started to face rapid population growth, designers and government bodies started to give preference to vertical construction as it allowed urban growth within bounds. Vertical construction, also referred to as high-rise buildings, has quickly become an integral method for the development and expansion of settlements into urban areas, and cities into megacities. As the trend for construction moves from horizontal to vertical, there is a need for engineers to introduce new concepts and notions for the engineering of high-rise buildings that are safe and structurally sound. This study focuses on the effect of vertical components of ground motion records on the performance of a typical high-rise buildings. To see the effect of the vertical ground motion, 100 earthquake records are selected according to the source-to-site distance, site class, and earthquake magnitude. A generic high-rise reinforced concrete building designed according to Turkish Building Seismic Code (TBSC18) has been evaluated in terms of inter-story drift ratio, overturning moment, column axial force, and story shear force under the selected earthquake records. According to the nonlinear time history analysis, it was observed that the vertical ground motion has a very slighly effect in terms of interstory drift ratio, overturning moment and base shear. However, it is observed that the vertical ground motion has a significant effect on the axial force on columns as expected. Results show that axial force (both compressive and tension) on a column, normalized with column axial capacity, is increased by 20% in the near-field zone. The observed maximum increase in compressive force is around 105%, 57%, and 68% of the column axial capacity for site classes A,B, anc C, respectively. When the results are examined in detail it is seen that the influence of vertical ground motion increases significantly when the contribution of horizontal ground motion is small. The above observations prove that the effect of vertical ground motion should be included during seismic design of high-rise structures.