1170.5 Reimagined: from a structural designers view
Our loadings code has adapted and extended to incorporate new knowledge as it has emerged over the last 50+ years: could a re-write encourage engineers to design better buildings? This paper outlines some intentionally provocative suggestions from a structural designers’ point of view, with the intention of promoting discussions which may assist future code committees. Basic changes suggested involve entraining Displacement Based Design and having all of the adjustment factors turning hazard to design forces (Sp and the like) in one place and explicit. This also allows updating the scaling of time history records to more clearly benchmark against the target spectra. Suggested simplifications for everyday use include; having non-linear design spectra (to save scaling for ductility/damping for different types of systems) and providing two-speed (simplified-conservative, or more detailed) approaches to Parts and P-Delta effects. Space should be made for some incremental inclusion of the rapidly evolving field of subsoil classification and still encourage designers to create buildings that are less prone to resonate with the ground. A great legacy from the Canterbury Earthquakes would be a code which dovetails in with current and future assessment and low -damage design guidelines and is flexible enough to apply to the incorporation of new technologies as they emerge.