A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 2000

An investigation on seismic performance of a large roof structure is ·carried out in this study. The structure is an important structure that covers the terminal building of the Second Bangkok International Airport, which is planned to be built in the year 2004. The investigation is necessary because a seismic hazard assessment of Bangkok conducted recently indicates that Bangkok, though located at a remote distance from seismic sources, is still at risk of damaging earthquake ground motions due to significant site amplification. In this investigation, several tasks are conducted. First, a finite element model of the entire structure is formulated by using a commercial program named STRAND (version 6.16). Second, an eigen analysis is carried out. The results show that the structure has a large number of vibration modes within the excitation frequency range, and many computed natural periods of these modes are closely spaced. Third, the vibration modes that will participate significantly in the seismic response are identified by using the concept of participation factor. Finally, a linear dynamic analysis is carried out. The responses are expressed in terms of the 84 percentile value of the maximum stress in all structural members. Based on the obtained results, it can be conclude that the structure is safe under earthquake ground motions at 72 and 475 years return period. However, it would experience a damage in some structural members under earthquake ground motions at 2500 years return period.