| Summary: | 碩士 === 臺灣大學 === 土木工程學研究所 === 98 === During the 1999 Chi-Chi earthquake in Taiwan, a large number of old buildings suffered from severe damage or complete failure, and there were thousands of casualties and a great loss of property. A large majority of building collapse resulted from the loss of vertical-load carrying capacities of columns. Most of the damaged columns were found with non-ductile detailing, such as widely spaced hoops with 90 degree end hooks. These columns are known to have poor seismic performance in terms of ductility and energy dissipation capacity. There are several important variables which can affect the strength and behavior of columns, such as axial load and hoop detailing. Therefore, six full scale specimens with light transverse reinforcement were tested quasistatically under cyclic lateral load with double curvature and constant axial load until failure to observe the behavior of flexural shear and axial failure of columns.
Test results show that under different magnitude of axial load, the collapse behavior is different in sense that higher axial load can accelerate the failure process. Columns with larger transverse reinforcement ratio can sustain higher lateral displacement capability. On the other hand, after shear failure, the lateral load resisting capacity of columns reduced significantly, leading to total lost of vertical-load carrying capacity. The flexural shear failure displacement is close to axial failure displacement.
The experimentally observed behavior is compared with predicted behavior based on several available analytical models. The ASCE/SEI 41-06 update assessment model provides the most closest estimations with the experimental results. Meanwhile, the models from Elwood and Moehle, Technology Handbook for Seismic Evaluation and Retrofit of School Buildings of NCREE, and Kuo et al. seem to overestimate the axial failure displacements.
|
|---|
