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Kohei Fujita, Izuru Takewaki
Engineering Structures, Volume 33, Issue 12, December 2011
Abstract
An enhanced and efficient methodology for interval analysis is proposed to evaluate the robustness of an uncertain structure. While a basic assumption of “inclusion monotonic” is introduced in some of the interval analyses, the possibility is taken into account of occurrence of the extreme value of the objective function in an inner domain of interval parameters. It is shown that the critical combination of interval parameters can be derived explicitly so as to maximize the objective function by second-order Taylor series expansion. Two different approaches, called the FRP (Fixed Reference-Point) method and the URP (Updated Reference-Point) method, are proposed to obtain such a critical combination of interval parameters. The method is applied to building structures with passive dampers sustained by flexible supports. The objective function is given by the sum of the mean squares of interstorey drifts under random input. The damper capacity, its supporting member stiffness and building storey stiffness are taken as interval parameters. In order to investigate the validity of the proposed methods, numerical analyses are conducted for 2- and 20-storey building models including passive dampers. By comparing the results with the reference solution and those by other conventional methods, it is demonstrated that the URP method can provide the most accurate response bounds without hard computational effort.
Additional Information
Dr.Fujita and Prof.Takewaki extended their URP method to elastic-plastic structures. To overcome a difficulty in computing response sensitivities of elastic-plastic structures, they devised an algorithm based on the concept of the response surface method. The interested readers should read the following paper.
K.Fujita and I.Takewaki, Robustness Evaluation on Earthquake Response of Base-Isolated Buildings with Uncertain Structural Properties under Long-Period Ground Motions, Architectoni.ca Journal, Vol.1, No.1, pp46-59, 2012. (http://ccaasmag.org/arch_v1-
In order to better understand the contents, the readers should read the following monographs:
(1) I.Takewaki, Dynamic Structural Design: -Inverse Problem Approach-, WIT Press (UK), 2000.
(2) I.Takewaki, Critical Excitation Methods in Earthquake Engineering, Elsevier, 2006.
(3) I.Takewaki, Building Control with Passive Dampers: -Optimal Performance-based Design for Earthquakes-, John Wiley & Sons Ltd. (Asia), 2009.
(4) I.Takewaki, M.Nakamura and S.Yoshitomi, System Identification for Structural Health Monitoring, WIT Press (UK), 2011.
(5) I.Takewaki, A.Moustafa and K.Fujita, Improving the Earthquake Resilience of Buildings: The worst case approach, Springer (London), 2012 (to appear).
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