SUMMARY: Monofunctional poly(tetrahydrofuran), (poly(THF)), having a 1-(diphenylmethyl)azetidinium end group (1) was prepared and subjected to an ion-coupling reaction with various mono-and plurifunctional carboxylates (2a -j). Multiarmed polymers having 2, 3, 4 and 6 arms were obtained in almost pure form by repeating a simple precipitation of a THF solution of 1 into an ice-cooled aqueous solution containing an excess amount of the relevant plurifunctional carboxylates (2 c -g) as sodium salts. Another model-branched polymacromonomer was obtained in high yield through the macromolecular ion-coupling reaction of 1 with poly(sodium acrylate) (2 h) of DP = 22. Moreover, the ion-coupling reaction of 1 with sodium (L)-tartarate (2 i) or sodium 2,29-dihydroxy-1,19-binaphthyl-3,39-dicarboxylate (2j) allowed one to introduce two hydroxyl groups at the center of a linear poly(THF) segment.
We developed a large tuned mass damper (TMD) for counteracting the effects of long‐period earthquakes in existing high‐rise buildings. The TMD consists of a suspended weight and oil dampers with stroke control functions. The damper increases its damping coefficient when the TMD weight velocity reaches a predetermined value, preventing overstroke during large earthquakes. The system controls the TMD stroke with minimum impact on its response control performance. This paper describes the development and application of the TMD and verification of the response control performance using observation records. First, we examine the requirements for this type of TMD using a simple analytical model and determine the influence of the stroke control on the response control performance. Next, an example application is outlined. The components required for realization of the TMD are addressed, and a project for the seismic upgrade of an existing high‐rise building is described. To evaluate the response control performance, we developed accurate simulation models for the building and TMD, and we analytically confirmed the response control performance. Finally, this paper presents observation records obtained during an earthquake and strong wind. The control effect of the TMD was verified through comparison of the observation records and analytical results.
<p>This paper describes a large TMD developed as an effective seismic control device for an existing high-rise building. There were two challenges to be overcome to realize the system. One is how to support a huge mass move in any direction, and the second is how to control mass displacement that reaches about 2 meters. As a solution to the former problem, a simple pendulum mechanism is adopted. To solve latter problem, we developed a high-performance oil damper with unique failsafe functions. This paper first examines the requirements of the TMD using a simple model and clarifies the constitution of the actual system. After the control effect through earthquake response analyses is discussed, the results of performance tests conducted on a full-scale TMD system for retrofitting an existing high-rise building are described.</p>
This paper proposes a stroke control strategy for seismic control of a structure that includes large-weight sub-systems. Although it is possible to provide a large mass ratio by utilizing a part of the structure's weight as a dynamic mass damper, there is a problem to secure enough stroke length of sub-system in actual design. This paper first defines optimum parameter settings of a sub-system that minimizes the response of a main-system based on random vibration theory using a 2DOF analytical model. After several examinations of the influence of a sub-system's parameter on the response reduction effect, a relational expression that connects sub-system's parameters and stroke is derived.Then the setting procedure based on the response spectrum is presented. By applying the proposed strategy, rational parameter settings of a sub-system matched with the design objective stroke can be obtained without performing any time history analyses.
This paper presents a response evaluation methodology for a seismic control structure that includes a large-weight sub-system as dynamic mass damper. The fundamental idea is considering the sub-system's stroke as amplification caused by the interaction with the main-system from the independent sub-system. First, the concept of the method based on a 2DOF model is introduced. Then it is expanded to a MDOF system. After examining the influence of the parameter variation based on random vibration theory, practical expressions are derived that describe the relations between variation and response. Finally, the validity of the method are discussed through numerical analyses.
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