The Science of Structural Revolutions

A perspective on the very human process by which scientific paradigms change can help point the path forward in any science, or in an applied science, such as Structural Engineering. Understanding this process of change, we can examine earthquake engineering, seismic building codes and theories of structural engineering for earthquake loads. When we take this perspective, we recognize that Structural Engineering for earthquake resistance is in the midst of a number of revolutions, from paradigms embodied in current building codes in which earthquake demands are associated with forces, to a new paradigm in which earthquake demands are re-envisioned as resulting from structural displacements or drift. The new paradigm is embodied in the current national standard for the seismic rehabilitation of existing structures, ASCE 41 [2] and the emerging standards for performance-based earthquake engineering (PBEE). Associated with this is the shift from design oriented towards life-safety to design for a range of performance objectives, such as life-safety, damage reduction, or immediate occupancy. With this perspective, we further recognize deficiencies in research and development. We have failed to systematically use the experimental and computational tools we possess to fill in the gaps of scientific knowledge. We have not developed and deployed appropriate frameworks to collect and share ideas and results. As one example, the formulation of performance-based codes now outstrips the knowledge-base needed to ensure that structures designed by the new tools will meet their performance objectives.