Factors influencing the seismic design and evaluation of post-installed steel anchors in concrete

Abstract

The recent Amendment to the New Zealand concrete structures standard 3101 requires post-installed anchors to be qualified and designed in accordance with the European standards ETAG 001, Annex E and EOTA TR045 respectively, moving away from the American standards defined in ACI 355 and ACI 318. This amendment was introduced because the European standards are newer and the seismic requirements are more stringent and arguably more applicable to an actual seismic loading scenario. Despite these improvements, several concerns remain in place regarding the suitability of both the European and the American standards for the seismic conditions encountered in New Zealand. A review of the qualification and design process as outlined in both the American and the European standards had been compiled, highlighting the differences in how seismic actions are addressed. The weaknesses and shortfalls of both standards from a New Zealand perspective are summarised, critical questions are introduced, and solutions are proposed. The objective of the study was to stimulate discussion amongst engineers to reach a consensus on how post-installed anchors should be designed and evaluated in a seismic environment. The eventual motivation is to decide on appropriate content for a future release of NZS 3101 Chapter 17.