Seismic assessment and fragility analysis of traditional Chinese timber frame building considering degraded connections

ABSTRACT

This paper studies the influence of degraded connections on dynamic characteristics, seismic response, and seismic fragility behaviors of traditional Chinese timber-framed buildings. Numerical models are developed based on the extended distinct element method, and calibrated with 1:3.52 scaled shake-table test data. The influence of fracture and wood aging on the performance of both mortise-tenon joints and Dougong brackets connections is discussed. A set of 20 ground motion records are selected for an incremental dynamic analysis, seismic behaviors, and fragility assessment. Results indicate that considering 0.75 times and 0.85 times degradation of mortise-tenon joints, natural frequencies are reduced by 8%, and 4%, respectively, and 4%, and 2% for Dougong brackets connections, respectively. The maximum acceleration response is reduced at most by 1.8% and 0.9%, respectively, and the maximum relative displacement is promoted by 7.3% and 5.3%, respectively. In addition, for a peak inter-structural layer drift of 1/442, 1/148, and 1/48, seismic intensities corresponding to median probabilities of exceedance of the structure with 0.75 times degraded performance of mortise-tenon joints are reduced by 32%, 16%, and 9%, respectively, and 14%, 6%, and 3% for Dougong bracket connections.

KEYWORDS:

• Degraded connections
• extended distinct element method
• incremental dynamic analysis
• seismic fragility analysis
• seismic performance assessment
• traditional Chinese timber frame buildings

Acknowledgment

Special thanks to Associate Professor Nakagawa Takafumi, at the Research Institute for Sustainable Humanosphere, Kyoto University (Japan), for his generous help and invaluable advice.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The research described in this paper was financially supported by National Natural Science Foundation of China (Grant No. 51978568, 51908454), National Key Research and Development Plan of the 13th Five-Year (Grant No. 2017YFC0703505), Shaanxi Key Scientific and Technological Innovation Team (Grant No. 2019TD-029), Natural Science Foundation of Shaanxi Province (Grant No. 2019JM-078), and Natural Science Basic Research Project of Shaanxi Province (Grant No. 2020JZ-50).