دانلود رایگان مقاله انگلیسی بهبود عملکرد لرزه ای کل ساختمان با استفاده از میراگرهای ویسکوز خطی مایع - اشپرینگر 2018

Abstract

Previous research has revealed that Eurocode-compliant structures can experience structural and nonstructural damage during earthquakes. Retrofitting buildings with fluid viscous dampers (FVDs) can improve interstorey drifts and floor accelerations, two structural parameters that characterize seismic demand. Previous research focusing on FVD applications for improving seismic performance has focused on structural performance. Structural parameters such as interstorey drifts and floor accelerations are often evaluated. Complexities arise as these parameters are often competing objectives. Other studies use damage indices that are influenced by several assumptions to represent performance. The use of repair costs is a more appropriate measure of total-building seismic performance, and avoids these limitations. This study investigates the application of linear FVDs to improve total-building seismic performance considering repair costs. The energybased method commonly used to calculate damper coefficients is modified to improve its accuracy. The optimal amount of damping with respect to repair costs (estimated using the FEMA P-58 procedure) is identified as 25–45%. This contrasts with a previously suggested optimal damping of 20–25%, based on structural parameters, that is frequently targeted. This study on the damping-repair cost relationship provides insight when selecting levels of damping for structural designs and retrofits. It also highlights that retrofit methods may be enhanced by using repair costs, rather than structural parameters. The FVD buildings significantly reduce both drift-sensitive and acceleration-sensitive damage. Structural damage is also negligible in the FVD buildings: a major step towards achieving building serviceability following an ultimate limit state level earthquake.

6 Conclusions

This paper has demonstrated a method of optimizing seismic performance of buildings through the addition of viscous dampers, by minimizing the total cost of both structural and nonstructural damage.

It was found that the energy formula underestimated the damping achieved by uniformly distributed viscous dampers. The energy method formula was modified to improve the accuracy of the damping ratio calculations by incorporating the effective modal mass. The mean absolute relative error between the target and achieved damping ratios was improved in comparison to the original energy method. The modified energy formula can be used to rapidly select the linear damper coefficients for a desired level of total damping and should be considered in future studies.

The optimal damping to minimize earthquake repair costs was found to be between 25 and 45% (considering uniform damping and linear FVDs). This contrasts with a previously suggested optimal damping of 20–25% total damping based on EDPs (Occhiuzzi 2009). The damping-repair cost relationship can provide insight when selecting levels of damping for structural design and retrofit. While practical considerations may sometimes prevent implementation of the highest levels of damping considered here, this highlights that retrofit decisions may be improved by using repair costs, rather than structural parameters.