DOI: 10.17603/ds2-shz7-gf65
title: Elastic Energy Dissipators via Multiple Elastic Instabilities
title: in Collaborative Research: Self-Centering Pendulum Shear Walls in Buildings via Nonlinear Elastic Kinematics

description: Elastic energy dissipation is possible by controlling the sequential snap-through elastic instabilities of periodically arranged slender elastic elements (units). The individual units exhibit a tailorable elastic limit-point response (snap-through instability) with a negative stiffness region. Their strategic arrangement and connection allows the generation of consecutive elastic snap-through buckling events that results in a hysteretic response with self-centering capability. Two novel elastic energy dissipating systems were studied. First, an energy-dissipative material that uses inclined beams in the material architecture was shown to manage the strain energy generated due to cyclic shear deformations and dissipate it through sequential snap-through instabilities. The second system consists of an arrangement in series of shallow cosine-curved domes, or multiple-cosine-curved-domes (MCCD) that results in an elastic flag-type hysteretic response with self-centering capabilities. The devices’ stiffness, strength, deformation capacity and energy absorption can be optimized through the design of the individual units and their geometrical arrangement. Both systems display repeatable response without damage and are insensitive to loading rate.
description: A new concept for unbonded post-tensioned shear walls was investigated with the objective of obtaining a system that performs damage-free and is self-centering under lateral loads from extreme events. The concept uses the complementary features of two systems: (1) a wall geometry with a circular profile at the footing interface, and (2) energy dissipation devices based elastic instabilities for use in coupled walls. This system is designated as a pendulum unbonded post-tensioned shear wall (UPSW) since the wall element rotates about a fixed point as it glides along the circular wall-base interface. The pendulum motion ensures that full contact is maintained between the wall and its base, resulting in negligible stress concentrations and energy dissipation through friction at the interface. For coupled pendulum UPSWs, supplemental energy dissipation and self-centering capabilities is provided by novel connectors that behave elastically yet provide hysteretic energy dissipation. Pendulum UPSWs address the limitations of traditional UPSWs with a flat interface, namely: concrete crushing at the wall toes, yielding of tendons, wall walking, and the need for supplemental energy dissipation.

Elastic energy dissipation is possible by controlling the sequential snap-through elastic instabilities of periodically arranged slender elastic elements (units). The individual units exhibit a tailorable elastic limit-point response (snap-through instability) with a negative stiffness region. Their strategic arrangement and connection allows the generation of consecutive elastic snap-through buckling events that results in a hysteretic response with self-centering capability. Two novel elastic energy dissipating systems were developed through analytical, numerical and experimental studies. First, an energy-dissipative material that uses inclined beams in the microstructure of the material architecture, was shown to manage the strain energy generated due to cyclic shear deformations and dissipate it through sequential snap-through instabilities. The second system consists of an arrangement in series of shallow cosine-curved domes, or multiple-cosine-curved-domes (MCCD) that results in an elastic flag-type hysteretic response with self-centering capabilities. The devices’ stiffness, strength, deformation capacity and energy absorption can be optimized through the design of the individual units and their geometrical arrangement. Both systems display repeatable response without damage and are insensitive to loading rate.