Impact of Near-Fault Ground Motions on the Efficiency of Passive Control Systems: Single Degree of Freedom System

• Main Authors: Chia-Ren Liu, 劉家仁
• Other Authors: Yin-Nan Huang
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/mx98q9

碩士 === 國立臺灣大學 === 土木工程學研究所 === 103 === ABSTRACT Passive control systems are used to improve seismic capacity of the structure and maintain the function and security of the main structure during an earthquake. In the far-fault region, passive control systems have been studied and proven to be an effective way to improve structural seismic capacity; however, the past record of near-fault earthquake is not as rich now, the advantage of structure equipped passive control elements cannot be estimated quantifiably subject near-fault earthquake. The difference between near-fault and far-fault earthquake is that near-fault record has a long period and pulse-like signal in velocity record. Seismic energy input structure in a very short time with pulse-like signal. The passive control systems are divided into two categories, isolation systems and damping systems. For the isolated structure, the displacement of isolator may be too large to control and leads isolator damage subject near-fault earthquake. For the damping structure, the input energy apply in the structure instantly. Whether the dampers can dissipate energy as good as far-fault region is a problem. In this study, single degree of freedom system is adopted to analyze the impact of near-fault ground motions on the efficiency of passive control systems. In the isolated systems, the study focus on lead rubber isolators ; in damping system, the elastic framework equipped liquid viscous dampers is adopted. The results is that the ratio of near-fault pulse period(Tp) and structure natural period is an important parameter of the maximum response. In the damping system, when the ratio is close to 1, the reduction of displacement and acceleration is the most effective than other ratio. When the structure natural period is much larger than the near-fault pulse period, the acceleration response will be magnified . For the isolation systems, when the ratio of the equivalent period and near-fault pulse period is about 1, the displacement reaction may be amplified than predict. Seismic assessment of passive control system have been proposed in this study when near-fault pulse period is known. Keywords: near-fault, near-fault pulse period, passive control, liquid viscous dampers, lead rubber bearing