No abstract

A tension/compression device is developed for applications as bracing elements in buildings. The device is designed to allow Nitinol forms, such as helical springs or Belleville washers, to be used in compression. The device allows both overall extension (tension) and compression while subjecting the Nitinol to an optimum deformation mode. It is possible, due to the versatility of the design, to adjust the force and stroke of the device without changing the overall configuration. This new device is subjected to a cyclic loading protocol that tests the Nitinol elementÕs ability to recover large deformations. The effect of different Nitinol configurations and a cyclic loading history are evaluated in the study. The results show that Nitinol helical springs produce good recentering and damping behavior while Nitinol Belleville washers show good potential to form the basis for a Nitinol damping device.

No abstract

ASCE 41 is the industry standard for seismic evaluation and retrofit of existing buildings. It allows for alternative component modeling and acceptance criteria based on a backbone curve constructed from envelopes of component hysteresis loops derived via experimental cyclic tests. ASCE 41-13 requires use of loading protocols having fully reversed cyclic loadings with increasing displacement levels. However, recent research summarized herein indicates the need for inclusion of different protocols that pay specific attention to behavior incipient to collapse. This view is supported by example building computer earthquake response simulations described herein. A generalized loading pattern derived from the simulations found relatively few drift excursions having one-direction bias, suggesting one-sided cyclic and/or monotonic tests may be better for describing building inelastic seismic demands.

No abstract