A new magnetostrictive force sensor is presented and its operation is verified experimentally. The sensor has a single excitation coil and a single detection coil, which utilize the magnetostrictive effect. The cores of the coils function as ‘‘spring elements’’ of the sensor, and are linked together by rigid end plates. The magnetostrictive force sensor is compensated for asymmetric magnetostrictive behavior, and measures both tensile and compressive forces. Force sensitivity increases with excitation current and coil turns, but is less influenced by excitation frequency.

SUMMARYActive energy dissipation is proved to be. very effective for abating seismic effects on buildings. The implementation of this concept in seismic design of buildings is studied by response simulations of a single storey building subjected to earthquake motion. Active energy dissipaters can be installed as part of the building lateral load bracing, and they regulate the strength and stiffness of the bracing during the building's response to the seismic events. The energy is dissipated when the bracing load exceeds the axial strength provided by the dissipater, and the bracing telescopes in and out. The design parameters of active energy dissipaters are described using the simulated response of a single storey building to ground pulse and harmonic ground excitation.The feasibility of the energy dissipater is demonstrated by the development and construction of a full-scale prototype device called an Active Slip Bracing Device (ASBD). The device utilizes Coulomb friction. The active characteristics are implemented by a computer controlled clamping mechanism on the friction interface. The ASBDs control of the strength and stiffness is investigated.

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