COMBINATORIAL OPTIMIZATION OF MULTIPLE-TYPE DEVICES IN SEISMICALLY ISOLATED BUILDINGS SATISFYING CONSTRAINTS IN RESPONSE HISTORY ANALYSES

DOI Web Site 1 Citations 8 References

Bibliographic Information

Other Title
  • 時刻歴応答制約を満足する免震建物の異種免震部材組合せ最適化

Search this article

Abstract

<p>A combinational optimization algorithm for the design of base-isolation devices (bearings and dampers) is proposed. Among multiple-type options in the devices, rational combinations with bearing and dampers are designed by applying the local search approach in the algorithm. The bearing sizes and numbers of dampers in addition to the device-types are treated as discrete design variables. For given structural conditions of superstructures, the total cost of the devices is minimized under the multiple constraints such as the maximum displacements in the isolation layers and floor accelerations in the superstructures. The responses under large earthquakes are simulated with multiple degree of freedom (MDOF) models of the superstructures in the response history analyses (RHA). The multiple Level 3 earthquake ground motions, which are recorded ground motions scaled and normalized as the maximum velocity of 75 kine, are used in RHA. The effects by higher modes are directly evaluated in RHA. The findings are as follows: </p><p>　</p><p>(1) A base isolation building with 21-story RC moment-frame superstructure was examined The natural rubber bearings (NRB) and sliding support with rubber-pad (SSB) are the design options for the bearing types. Also, the lead dampers (LD) and oil dampers (OD) are the options for the dampers. The effectiveness of using the proposed algorithm was confirmed by comparing the results with those by the alternative algorithm for fixed-device design. The obtained design solutions are defined as superior solutions, in which the constraints of maximum displacement in the isolation layer and bearing pressure under the sustained load are governing in the examined structure. The superior solutions are not globally optimized solutions but are rationally designed independent of the engineer’s skills.</p><p>　</p><p>(2) The effects in the responses induced by higher vibration modes were confirmed by a comparison of the responses with the models with rigid superstructure. While the difference between the MDOF and rigid models is less than 20 % in the responses of the maximum displacements at the isolation layers, the floor accelerations and story shear coefficients in higher stories are significantly greater (more than twice) in the MDOF models than rigid models. The proposed algorithm takes into account the higher-mode effect, which can significantly influence the floor accelerations and story shear coefficients.</p><p>　</p><p>(3) The influences in the superior solutions by the design constraints regarding the displacement in the isolation layer, floor accelerations and elastic base-shear coefficient were investigated. The ODs, whose cost is relatively high, are more used for desisting the floor accelerations at higher stories under the greater seismic ground motions and smaller displacement constraints at the isolation layer. In contrast, SSBs are more used rather than LDs for increasing the elastic lateral strength of the isolation layers, which is required for the design against wind loads. The usefulness of the proposed algorithm was confirmed through this study, identifying the governing design constraints for various superior solutions.</p>

Journal

Citations (1)*help

See more

References(8)*help

See more

Related Projects

See more

Keywords

Details 詳細情報について

Report a problem

Back to top