非線性結構系統識別之研究

Abstract

在兼顧安全與經濟之原則下,現行的建築耐震設計準則容許結構在強震中 產生局部之破壞,惟結構須有足夠的韌性以避免突然崩塌的危險.據此理念 所設計之結構以及老舊建築物,在歷經強震後鮮有不遭破壞者,因此對受損 結構進行迅速之檢測與安全評估為一相當實際之問題.直覺上,吾人認為結 構受損後會有軟化現像,蓋因勁度損失造成結構周期變長所致.吾人可由結 構在強震中周期變化的情形研判其是否受損,再決定是否進行進一步之評 估與修復工作.發展適當的系統識別方法為建立有效之結構破壞偵測與安 全評估程序的基礎. In order to accomodate concerns on both safety and economy, theseismic design criteria adopted by the building code currentlyin practice allows partial damage of structures during severe earthquakes,provided that sufficient ductility of structureis available to avoid a sudden collapse.Structrres designed under such a concept or aged can rarely survive without anydamage after experiencing strong earthquakes. Therefore,itis really a pracrical issue to be able to quickly performdamage detection and safety assessment of damaged structuresonce occurred. We think intuitively that a structure willbecome"softened"after being damaged,since the vibrational period of the structure will be lengthened as a result ofstiffness loss.One may judge whether a structure is damagedin the first place from the variations of its natural frequenctes, and determine if further assessment and reinforcement id desired.Development of a proper system identification technique is the basisof establishing an effective damage detection and safety assessmentprocedure for structures.