Comparative Research Between a Core-Walled Fixed Base and a Base Isolated Tall Buildings

Abstract

This study seeks to evaluate and compare the effectiveness of the two predominant seismic protection methodologies employed for safeguarding tall buildings against seismic forces in regions prone to high seismic activity. One such approach that is widely used to resist lateral loads caused by seismic loads is the earthquake-resistant method. In this design approach, the structure is made rigid usually by applying a concrete core wall to resist lateral loads. This method is widely used in USA. Another design approach is the structure response control method which focuses on increasing the damping and/or period of the structure in most cases making the structure flexible while dissipating energy. This method is widely used in countries like Japan to protect buildings. The two conventional methods of seismic protection are presented in this research to compare the seismic behavior of the structures under seismic demand. Numerous seismic isolation devices with periods of up to 4 seconds have been developed and are extensively utilized in seismic-prone regions, including but not limited to Japan, China, New Zealand, and Turkey. These devices are commonly applied to a variety of buildings for enhanced seismic protection. A tall building with a concrete core wall was selected and used. The dynamic performance of a high-rise RC building with a shear wall core is compared to a redesigned model of the same building with base isolators inserted between the mat foundation and the foundation slab. A redesign of the sections of the building with base isolators was then carried and compare to a core-walled fixed base building with the original section properties. The design and seismic performance of the two buildings under seismic demands is presented. The thickness of the core wall was reduced by 37.78% and shear wall reinforcement by 34.10% due to the addition of base isolation. This translated to a cost reduction $1300641 that is almost equal to the estimates cost of procuring lead core rubber isolators which is $1306800. The peak floor accelerations at the roof and base shear responses of the Base isolated building structure were 78% and 58% on average lower than the core-walled fixed base structure respectively. The story drift ratios are well within the limits prescribed by the code. i.e. seismic (1/50) and wind design loading (1/400) respectively for both cases. Fundamental period of the base isolated structure was larger (6.95sec) when compared to the core-walled fixed base building (4.6sec). © 2024, International Organization on 'Technical and Physical Problems of Engineering'. All rights reserved.