Seismic performance evaluation and economic feasibility of self-centering concentrically braced frames.

摘要

Self-centering concentrically braced frame (SC-CBF) systems have been developed to increase the drift capacity of braced frame systems prior to damage to reduce post-earthquake damages in braced frames. However, due to special details required by the SC-CBF system, the construction cost of an SC-CBF is expected to be higher than that of a conventional CBF. While recent experimental research has shown better seismic performance of SC-CBF system subjected to design basis earthquakes, superior seismic performance of this system needs to be demonstrated for both structural and nonstructural components in all ground motion levels and more building configurations. Moreover, Stakeholders would be attracted to utilize SC-CBF if higher construction cost of this system can be paid back by lower earthquake induced losses during life time of the building.;In this study, the seismic performance and economic effectiveness of SC-CBFs are assessed and compared with CBF system in three building configurations. First, probabilistic demand formulations are developed for engineering demand parameters (inter-story drift, residual drift and peak floor acceleration) using results of nonlinear time history analysis of the buildings under suites of ground motions. Then, Seismic fragility curves, engineering demand (inter-story drift, peak floor acceleration and residual drift) hazard curve and annual probabilities of exceeding damage states are used to evaluate and compare seismic performance of two systems. Finally, expected annual loss and life cycle cost of buildings are evaluated for prototype buildings considering both direct and indirect losses and prevailing uncertainties in all levels of loss analysis. These values are used evaluate economic benefit of using SC-CBF system instead of CBF system and pay-off time (time when the higher construction cost of SC-CBF system is paid back by the lower losses in earthquakes) for building configurations. Additionally, parametric study is performed to find acceptable increase in cost of SC-CBFs comparing to CBFs and impact of economic discount factor, ground motion suite and building occupancies on economic effectiveness of the SC-CBF system in three configurations.;Results of this study indicates that, SC-CBF system generally shows better seismic performance due to damages to structural and non-structural drift sensitive components but worse performance due to damages to acceleration sensitive components. Therefore, loss mitigation in structural and non-structural damages are major source of economic benefit in SC-CBFs. SC-CBF system is not feasible for high rise buildings and low seismic active locations. If the cost of SC-CBFs are twice as CBF frames, the higher cost is paid back in a reasonable time during the life time of the buildings. SC-CBFs are more feasible for banks/financial institutions than general office buildings.