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 energy-based 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.
Highlights
Previous research has revealed that concentric braced frame (CBF) structures designed using the Eurocode (CEN 2010a) can experience structural and nonstructural damage during earthquakes
The energy method formula for linear fluid viscous dampers (FVDs) is reproduced in Eq 4, where fd;n is the supplemental damping ratio in mode n, hj is the angle of damper inclination at storey j, /2rj is the relative modal displacement, and /i is the modal displacement of mass mi
This is in contrast to a previously suggested optimal damping of 20–25% total damping based on engineering demand parameters (EDPs) (Occhiuzzi 2009)
Summary
Previous research has revealed that concentric braced frame (CBF) structures designed using the Eurocode (CEN 2010a) can experience structural and nonstructural damage during earthquakes. Our use of repair costs is a more appropriate measure of total-building seismic performance and avoids these limitations. The optimal amount of damping with respect to repair costs is investigated using the FEMA P-58 procedure (FEMA 2012b). The seismic performance of the FVD-retrofitted buildings is evaluated and limitations of FVD performance improvements are identified. One of the first loss estimation methods, referred to as assembly-based vulnerability, was proposed by Porter and Kiremidjian (2001) In this method, the entire building is considered as a collection of individual components. It is the first study to investigate optimal damping using repair costs and the FEMA P-58 procedure. Nonlinear FVDs are often used in practice, and an obvious extension would be to consider nonlinear dampers
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have