Structural Engineering Issues for a Large Cascadia Event

Overview Need a Framework and Methods for Structural Hazard Assessment Under Long-Duration Motions Many Knowledge Gaps and Data Needs Two Zones Coastal (intensity and tsunami post-earthquake) Valley (attenuated motions and site specific responses) Swiss Agency for Development and Cooperation

Seismic Hazard Analysis for Long-Duration Motions Event scenarios (fault rupture, magnitude) Attenuation (changes over distance) Site specific responses (local shaking, soil behavior) Structural fragility (how building responds to shaking) Performance (damage/collapse) Fire Rahman and Mashfiq, ADPC

Build Case for Investment Predicts: Physical damage to residential and commercial buildings, schools, critical facilities, and infrastructure; Economic loss, including lost jobs, business interruptions, repair and reconstruction costs; and Social impacts, including estimates of shelter requirements, displaced households, and population exposed to scenario floods, earthquakes, and hurricanes. HAZUS-MH

Building Inventory Oregon Growth prior to hazard recognition (and after!) Unengineered buildings Foundations Reinforced concrete and masonry UR masonry Discontinuities Large Openings Soft stories Short columns Torsional eccentricities Elevation and plan stiffness changes Parapet walls Pounding

Fragility Curves for Building Inventory Describes Damage to Building as Function of Input (PGA) Slight damage to collapse Statistical Functions Unengineered buildings Foundations? New ones needed PGA adequate parameter? Optimistic?

Key Issues Building stock No shake out Fragility Curves for PBE Need input motions Real and synthetic Current Codes Adequate for New Design? Retrofit Methods for Existing Stocks High performance materials ($) Hybridized designs Tsunami Tsunami after Seismic