vibrations project - Bulletin of the Department of Geology...

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Bulletin of the Department of Geology, Tribhuvan University, Kathmandu, Nepal, Vol. 10, 2007, pp. 55–62 Dynamic analysis of foundation of Bir Hospital Trauma Centre, Kathmandu, Nepal * Ajay Raj Adhikari and Prakash Chandra Adhikary Central Department of Geology, Tribhuvan University, Kathmandu, Nepal ABSTRACT The rapid incrase in population of Kathmandu metropolitan city in last two decades has demanded the construction of multistoried buildings. As the height of building increases, variation in moments and force along the height of the structure becomes vulnerable and is more pronounced when the structure rests in soft fluvio-lacustrine sediments like in the Kathmandu Valley. Similarly, the amplitude of vibration causes bending of rebars which can damage the foundation and ultimately the building, if proper care is not taken during the design phase. Therefore, this paper aims in calculating the amplitude of vibration at natural frequency, seismic interial force and its change for the height of the Bir Hospital Trauma Centre, Kathmandu. The elastic parameter, modulus of elasticity needed for analysis was estimated from a graphical method. Shear modulus was calculated using empirical ralation. Density of strate was estimated in the laboratory and load of the structure was referred from Indian Standard of design loads. The maximum amplitude of vibration calculated was 12 mm at 19.3 Hz whereas it was 1.5 mm at the natural frequency for all portions avoiding coupling effect. The variation in seismic horizontal force and moment was largest at the height of 9–15 m showing the possibility of failure at such height at the time of earthquake. *Corresponding author: E-mail address: [email protected] Bulletin of the Department of Geology INTRODUCTION The Kathmandu Valley lies in a synclinal basin filled up by fluvio-lacustine sediments of Pleistocene age (Yoshida and Igarashi 1984). Bir Hospital lies in the core of the Kathmandu City (Fig. 1). The surrounding area is incorporated by heavily constructed buildings and those which are being constructed. Most of the buildings of the area belong to public concern parties. The Bir Hospital Trauma Centre is seven storied with raft foundation above 12 mm thick slab over the back filled boulders. The major portion of the structure is founded at the depth of 8 m and the arch shaped portion (Fig. 2) lies at the depth of 4 m. Dynamic characteristics of the foundation was not considered as a compulsory work in construction except for the major buildings due to lack of legal act and awareness among builders. To aware the builders about subsurface soil behavior and suitable foundation design which has less risk from earthquake vulnerability, this paper primarily focuses on vibration of the foundation at natural frequency and at the time of earthquake. Because enough data on the elastic properties of soil of the study area was not available, evaluation of the vibration analysis of foundation was crried out by
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This note was uploaded on 04/17/2010 for the course MENG 17781 taught by Professor Sang during the Spring '10 term at University of Texas-Tyler.

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vibrations project - Bulletin of the Department of Geology...

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