Loading Protocols for ASCE 41 Backbone Curves

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.