ABSTRACT

1. ABSTRACT Earthquakes can and do happen in the Southeastern United States. In areas where earthquakes are likely to occur, knowing where to build and how to build can be helpful in reducing property damage. This study involves producing a detailed earthquake analysis of an existing high-rise structure in the southeast region. The analysis of the structure is based on the effects of past earthquakes in the Eastern United States. The probability of structural and non-structural damage, caused by the building’s displacement, was approximated through the use of fragility curves. Repair costs were estimated based on the probability of exceeding each damage state. Passive control devices were used to improve the response of the building and reduce the extent of damage. The findings of this study will be used as a means of educating both students and professionals on the importance of earthquake hazards in the southeast region. BACKGROUND While hurricanes have historically been the main cause of damage to structures located in the Eastern and Southeastern United States during the June-November period, the probability of earthquakes in this region cannot be ignored. Believe it or not, earthquake hazard is prevalent in this area. Most earthquakes occur at the boundaries of tectonic plates (e.g., California), however, they can occur in inner zones. This is most likely caused by the build-up of strains from pressures developed at the plate boundaries (Hu 1996). The most notable events of this type were the New Madrid earthquakes of 1811-1812 and the Charleston earthquake of 1886. The four New Madrid earthquakes were the largest intraplate earthquakes in the world. The Mississippi River changed its course, the land surface sunk to form new lakes and the violent shaking snapped off trees. The Charleston earthquake, whose maximum intensity and magnitude were equal to X and 7.3, respectively, caused damage for an estimated $5,000,000 and was felt as far as 160 km away from the epicenter. This was the most damaging earthquake ever to strike the Eastern United States. To date, there have been more than 60 earthquakes in the Charleston area. On April 13, 1998, a small earthquake of magnitude 3.9 shook Kershaw County, SC, and on April 30, 2003, Fort Payne, Alabama experienced a 4.9 magnitude earthquake. The quake was felt throughout the state, however, there was no damage. The probability of another event like the 1886 earthquake occurring somewhere in the Eastern United States is equal to 40-60% in the next 20 years (Nishenko and Bollinger 1990, Sibol et al., 1990). Mitigation of the effects of earthquakes is no longer a goal in earthquake-prone areas only. Therefore, there is a need to develop a methodology to guide future decision-making regarding seismic hazard. OBJECTIVE Analyze the effects of an earthquake on an existing structure constructed in the southeastern region of the United States; Turlington Building, Tallahassee, Florida. Relate building motion to probability of damage. Approximate the amount of earthquake damage, in terms of monetary cost. CONTROL TECHNIQUE DAMAGE APPROXIMATION RESULTS CONCLUSION FEM was effective in capturing the dynamics of the structure The proposed method is effective in relating the building response to repair cost TMD and BI were effective in reducing building vibration TMD and BI reduced the amount of the repair cost by 70+% A magnitude 8 earthquake damaged 30% of the structure, approx. $12 million worth ACKNOWLEDGEMENTS This research was carried out under the supervision of Professor Makola M. Abdullah, and supported in part by the Multidisciplinary Center for Earthquake Engineering Research. Earthquake Analysis of an Existing Structure in the Southeast Region of the United StatesTerri Norton and Makola M. Abdullah, Ph.DWind Hazard & Earthquake Engineering LabFAMU-FSU College of Engineering • : median value of spectral displacement at which the building reaches the threshold of damage state, ds. • : is the standard deviation of the natural logarithm of spectral displacement for damage state, ds. • : is the standard normal cumulative distribution function. Structural Damage: Nonstructural Damage: Total Damage from Displacement: • RCS, RCD: repair cost to structural and displacement-sensitive damage, respectively • PMBTSTR: probability of model building type j being in structural damage state ds • PONSD: probability of occupancy I being in nonstructural damage state ds • CI: cost index multiplier (local index = 0.8) • FA: floor area (FEMA, 1998) CHARLESTON RESPONSE NEW MADRID RESPONSE Equation of Motion: Base Isolator: Tuned Mass Damper: (Chopra 2001) (Rana 1998)