Spherical sliding isolation bearings with adaptive behavior: Theory

Abstract

SUMMARYThe principles of operation and force-displacement relationships of three novel spherical sliding isolation bearings are developed in this paper. These bearings are completely passive devices, yet exhibit adaptive stiffness and adaptive damping. That is, the stiffness and damping change to predictable values at calculable and controllable displacement amplitudes. The primary benefit of adaptive behavior is that a given isolation system can be separately optimized for multiple performance objectives and/or multiple levels of ground shaking. With the devices presented here, this is accomplished using technology that is inherently no more complex than what is currently used by the civil engineering profession. The internal construction consists of various concave surfaces and behavior is dictated by the different combinations of surfaces upon which sliding can occur over the course of motion. As the surfaces upon which sliding occurs change, the stiffness and effective friction change accordingly. A methodology is presented for determining which surfaces are active at any given time based on the effective radius of curvature, coefficient of friction and displacement capacity of each sliding surface. The force-displacement relationships and relevant parameters of interest are subsequently derived based on the first principles.

Semi-Active Control Systems in Bridge Engineering: A Review of the Current State of Practice

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The Relationship between Affective and Social Isolation among Undergraduate Students

“…Everyone experiences affective isolation, but in different degrees and at various times. However, it reaches its peak during adolescence; adolescents are considered the largest group to be affected by affective isolation (Fenz & Constantinou, 2008). Certainly, low levels of self-confidence, less containment and communication, and decreased interactions with friends increases a predisposition towards affective and social isolation.…”

“…Behaviorists assert that there is conflict between processes leading to behavior and those leading to inhibition. The latter are a result of individuals' inability to abandon old conditional responses acquired in childhood, which lead to the development of inappropriate habits that do not facilitate an effective, successful life with others (Fenz & Constantinou 2008).…”

Control De Aceleraciones De Entrepiso Para Sistemas Estructurales Con Aislamiento Sísmico De Base

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