Seismic Retrofit Study of Rectangular RC Bridge Columns using FRP (二)

近年來美、日等國分別發生強烈地 震，大量橋梁嚴重損壞或倒塌，使交通嚴 重受阻，造成救災及災後重建之困難。由 災後報告及研究指出，倒塌或嚴重損壞之 橋梁大多為未經現代補強技術加以耐震加 固之既有橋梁，其破壞模式和以往橋梁之 震害大致相同，都顯示出以往設計觀念及 規範之缺失。台灣地區地震頻繁，近年來 雖無大地震發生，但橋梁耐震設計規範大 多依循美、日等國，因此一旦有大地震發 生，類似之橋梁震害極可能重現於我國。 因此，如何對國內現有耐震能力不足之橋 梁進行補強，使其於強震下不致於嚴重損壞或倒塌乃為當務之急。 美國自1971 年以來即持續地進行橋梁 耐補強技術之研究與應用，目前研究已較 成熟且已應用於實際工程之橋柱耐震補強 技術包括鋼板包覆法，FRP 包覆法，及RC 包覆法等。國內目前橋梁問題甚多，對極 需補強之橋柱則尚未有一套針對國內橋梁 設計施工特性所擬訂之耐震補強技術及設 計施工準則。尤其重要的是，國內以往所 制定之設計規範，大多依循美、日等國。 截至目前為止，尚無較完整之本土性試驗 資料可供研擬耐震設計及評估補強方法所應用。The 1994 Northridge earthquake and 1995 Kobe earthquake have caused catastrophic loss in human life and property loss in both the US and Japan. Due to the large amount of bridges collapsed or severely damaged, emergency handling and recovery from the disaster became extremely difficult. Research and investigation after the earthquakes showed that most of the bridges collapsed or severely damaged were existing bridges without being strengthened by modern seismic retrofit techniques. In addition, the failure types and damage patterns are similar to those observed in many previous earthquakes. This reveals the inadequacy of the seismic design code and construction practice in the past. Taiwan is in a region of very frequent seismic activities. In addition, most of the earlier seismic design codes in Taiwan closely followed those of the US and Japan. Although there has been no major earthquake occurred in recent years, similar types of bridge damage may happen here in case of a strong earthquake. Therefore,it is a very urgent matter to seismically retrofit the existing bridges in Taiwan to minimize the possibility of bridge collapse or severely damage in the future. The USA, typically the Caltrans has been carrying out seismic retrofit research and applications since 1971. One of the seismic retrofit measures that have been proved effective and economical is the FRP (Fiber reinforced Plastics) wrapping/jacketing methods on RC bridge columns