P-△ effect on inelastic displacement ratio spectra for inelastic structures

• 作 者: ZHAI Chang-hai LI Ning MA Yu-h
• 机 构: School of Civil Engineering,Earthquake Engineering Research and Test Center,Institute of Engineering
• 出 处: 哈尔滨工业大学学报（英文版）
• 发表日期: 2004年期
• 关键词: constant-ductility displacement ratio spectra inelastic displacement estimation
• 基金项目: Opening Laboratory of Seismic Control and Structural Safety Foundation;Opening Laboratory of Earthquake Engineering and Engineering Vibration Foundation;国家自然科学基金

For the evaluation of structures with known ductility demands, the constant-ductility displacement ratio spectra (CDDRS) are particularly useful for providing inelastic displacement ratios to estimate maximum lateral inelastic displacement demands from maximum elastic displacement demands.The CDDRS are computed for single-degree-of-freedom systems (SDOF) by considering or ignoring P-△ effect for different ductility levels when subjected to 344 earthquake ground motions recorded in four site classes.The modified expressions of CDDRS for P -△ effect are proposed.It is concluded that the P- △ effect on CDDRS is significant, and the effect increases with the increase of ductility level.In the long-period region, the CDDRS ignoring P-△ effect almost conforms to the equal-displacement rule.But in the case of higher ductility level, the CDDRS considering P-△ effect are much higher than 1.0, which do not conform to the equal-displacement rule.