Risk-Consistent Design Approach for Designing Innovative Hazard-Resistant Structures

Abstract

This paper first introduces an innovative Composites Structural Insulated Panels (CSIPs) for structural wall and floor applications against multiple hazards, and then presents an innovative risk consistent design approach for designing such system. The proposed composite panel is made of low cost thermoplastic orthotropic glass/polypropylene (glass-PP) laminate as a facesheet and Expanded Polystyrene Foam (EPS) as a core with very high facesheet/core moduli ratio. The proposed CSIPs are intended to overcome problems of traditional wood panels against multiple natural hazards including earthquake, flood and windstorm to poor penetration resistance against wind borne debris, termite attack and mold buildups… etc. On the other hand, despite most of recent structures have been designed according to the desired code requirements, failure of those structures due to recent natural hazards such as hurricanes and earthquakes have shown the weakness of the current design methods. It has also raised the need for a new methodology for structural design that accounts for the risk due to natural hazards. Therefore, a comprehensive design approach for developing hazard-resistant structures was developed. The approach considers the life cycle cost (LCC) of the structure and safety indices for strength and drift. It accounts also for the uncertainty in both loading and strength. The variability in the strength, drift and load is expressed by mean values with their coefficient of variance (C.O.V) which is referred to aleatory uncertainty. The LCC was calculated based on the concept of quantitative risk assessment (QRA) that incorporates the damage cost due to a certain hazards and the probability of occurrence of those hazards. Based on the importance and the type of the structure, the structural engineer and the decision maker can determine or optimize the most appropriate building model. The method was demonstrated with case studies on two structures: one for traditional wood and another for CSIP. Seismic and wind hazard were considered in the analysis. Two locations were considered; Los Angeles, CA and Charleston, SC. These locations are critical for seismic and wind load; respectively. The results showed that CSIP building is cost effective and provides higher safety indices than traditional wood structure.