Experimental and Analytical Study on Retrofit of Buildings by Adding Reinforced Concrete Walls with Asymmetric Openings

• Main Authors: Yi-En Lin, 林毅恩
• Other Authors: Lap-Loi Chung
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/334j98

碩士 === 國立臺灣大學 === 土木工程學研究所 === 105 === Significant earthquakes happened in recent years, such as Chi-Chi earthquake in 1999, reflected insufficient seismic capacity of many public and residential buildings. Therefore, there are many retrofit solutions proposed, and retrofit method of adding reinforced-concrete walls (RC walls) was commonly adopted by engineers. Although retrofit method of adding RC walls provides high lateral strength and stiffness, this method results in lack of lighting and ventilation and also affects the interior route of the building. Hence, National Center for Research on Earthquake Engineering (NCREE) in Taiwan planned the retrofit method of adding RC walls with openings. The research in previous years from 2014 to 2015 focused on retrofit of adding RC walls with symmetric openings. However, retrofit method of adding RC walls with asymmetric openings is needed for engineers and building users, and there is little domestic and foreign experimental research on this method. This research focused on the influence of asymmetric-opening RC walls on seismic capacity, and it allowed engineers to design a retrofitting RC wall to fulfill clients'' requirement and seismic demand. Three retrofitted specimens with asymmetric openings were planned. These specimens included different locations of openings and a retrofitting wall with a window and/or a door. They were designed to retrofit an existing bare frame with a net span of 420cm and net height of 300cm. Pushover tests of these specimens were performed in NCREE. Experimental results showed that the asymmetric-opening specimens enhanced to about 8.9 times of lateral strength, and at least 65 times of stiffness of the bare frame; the symmetric-opening specimen enhanced to about 8.2 times of lateral strength and 34 times of stiffness of the bare frame. This research verified that the retrofit method of adding RC walls with asymmetric openings is feasible and effective, and these retrofitted frames were able to participate in early earthquake force distribution. Drift ratio of all retrofitted specimens could go up to 2%. This research used Technology Handbook for Seismic Evaluation and Retrofit of School Buildings, Third Edition, published by NCREE to evaluate the seismic performance of 9 retrofitted specimens. The analytical method introduced by the handbook may overestimate lateral strength of certain specimens with wall piers of low height-width ratio. Therefore, an improved method and plastic-hinge models were proposed as reference for engineers and researchers.