Scenario-based multi-risk assessment from existing single-hazard vulnerability models. An application to consecutive earthquakes and tsunamis in Lima, Peru

Multi-hazard risk assessments for building portfolios exposed to earthquake shaking followed by a tsunami are usually based on empirical vulnerability models calibrated on post-event surveys of damaged buildings. The applicability of these models cannot easily be extrapolated to other regions of larger/smaller events. Moreover, the quantitative evaluation of the damages related to each of the hazard types (disaggregation) is impossible. To investigate cumulative damage on extended building portfolios, this study proposes an alternative and modular method to probabilistically integrate sets of single-hazard vulnerability models that are constantly being developed and calibrated by experts from various research fields to be used within a multi-risk context. This method is based on the proposal of state-dependent fragility functions for the triggered hazard to account for the pre-existing damage and the harmonisation of building classes and damage states through their taxonomic characterisation, which is transversal to any hazard-dependent vulnerability. This modular assemblage also allows us to separate the economic losses expected for each scenario on building portfolios subjected to cascading hazards. We demonstrate its application by assessing the economic losses expected for the residential building stock of Lima, Peru, a megacity commonly exposed to consecutive earthquake and tsunami scenarios. We show the importance of accounting for damage accumulation on extended building portfolios while observing a dependency between the earthquake magnitude and the direct economic losses derived for each hazard scenario. For the commonly exposed residential building stock of Lima exposed to both perils, we find that classical tsunami empirical fragility functions lead to underestimations of predicted losses for lower magnitudes (Mw) and large overestimations for larger Mw events in comparison to our state-dependent models and cumulative-damage method.</p

Elastic response of cross-laminated engineered bamboo panels subjected to in-plane loading

© ICE Publishing: All rights reserved. Novel cross-laminated bamboo panels comprising three and five layers (G-XLam3 and G-XLam5) were tested in compression along the main (0°) and the transverse (90°) directions. Linear variable differential transformer (LVDT) and non-contact three-dimensional digital image correlation (DIC) measuring techniques were used separately to measure deformation in the elastic region, and the elastic moduli, Ep C,0 and Ep C,90, were derived. Mean elastic modulus values obtained using LVDTs exhibited a good match with analytically predicted values. In contrast, the elastic values obtained by the DIC method were considerably higher and presented a considerable scatter of results. For instance, the Ep C,0 for G-XLam3 and G-XLam5 panels were 17·22 and 15·67 GPa, and 14·86 and 12·48 GPa, using the DIC and LVDT methods, respectively. In general, G-XLam panels with a fifth of the cross-sectional thickness and twice the density of analogous cross-laminated timber exhibited an approximately two-fold increase in Ep C,0 and Ep C,90. Overall, this research provides guidelines for the assessment and standardisation of the testing procedures for similar engineered bamboo products using contact and non-contact methods and highlights the potential of using G-XLam panels in stiffness-driven applications and in combination with wood for structural purposes