Risk-targeted hazard maps for Spain

Abstract

Many studies have demonstrated that the design of structures in a region through the uniform hazard principle does not guarantee a uniform collapse risk. Even in regions with similar Peak Ground Accelerations (PGAs) corresponding to the same mean return period, the seismic risk in terms of collapse probability will be significantly different mainly due to the shape of the hazard curves as well as uncertainties in structural capacities. In this paper, risk-targeted hazard mapping is being explored in peninsular Spain using a recently updated seismic hazard map. Since risk targeting involves multiple input parameters such as the model parameters of fragility curves, their variability was considered through their probability distribution as observed in reinforced concrete (RC) moment frame buildings, representing the most common building typology in Spain. The influence of the variation of these parameters on the risk results were investigated, and different assumptions for estimating the model parameters of fragility curves are illustrated. These assumptions were included in a fixed (generic) fragility curve or building-site-specific fragility curves. Different acceptable damage states (i.e., collapse and yielding) were considered concerning Spain’s seismicity level. Finally, the maps for risk-targeted design ground motions and risk coefficients are presented. It is outlined that the employment of risk-targeted analysis leads to the modifications for existing design ground motions due to the different shape of the hazard curves across Spain and considering the uncertainty of structural capacity. Moreover, it is found that using the building- and site-specific fragility curves could result in a more uniform seismic risk across the country.

Prospective study on risk-targeted seismic hazard maps for Northeastern Brazil: case study in Zone 1 of ABNT NBR 15421:2006

“…Some differences between the approaches therein [19], [26] and the one adopted in this paper are addressed in the following: (i) ASCE 7-16 provisions [26] are based on an acceptable p f of 1% in 50 years (2 × - 4 10 in one year), and P[C|IM D ] of 0.1. Herein, more stringent values of probabilities (i.e., lower p f and P[C|IM D ]) are explored, based on more recent risk-targeting studies conducted for other regions worldwide, especially low seismicity ones like Brazil [11]- [13];…”

“…In this regard, risk-targeting approaches have emerged, as an alternative to the common Uniform Hazard maps, to provide Uniform Risk maps, i.e., design accelerations that provide a uniform failure probability across a region [10]. For example, Douglas et al [12] and Kharazian et al [13], using the risk-targeting methodology, identified different reductions or increase of the accelerations relative to the uniform hazard maps of 475 years RP depending on the seismicity of the site (i.e., low, moderate or high).…”

“…Similarly, the Indonesian code, SNI 1726:2012 (SNI [14]; see also Sengara et al [15]), also adopted risk-targeted maps. This methodology has also been applied for several other regions worldwide, for instance, France [12], Spain [13], Romania (Vacareanu et al [16]), Iran (Taherian and Kalantari [17], Talebi et al [18]); and at continental scale for Europe [11] and South America (Petersen et al [19]). A state of the art of the risk-targeting approach can be found in Douglas and Gkimprixis [20].…”

“…Contrastingly, Douglas et al [12] considered the probability too high for France and adopted a more conservative criterion (i.e., -5 10 ) . Therefore, in this paper, we seek to explore the impact of different (and more restrictive) acceptance criteria, in view of similar works [11]- [13], as well as other parameters considered in the risk-targeting methodology.…”

State of the art of seismic risk and loss assessment in structures

“…Different structures are designed and analyzed using the same peak ground acceleration (PGA), but the possible risk of damage that occurs may not be the same, especially in the shape of the hazard curve and uncertainty in structural capacity. Of course, it depends on the condition of the structure, and the condition of the soil around the building [6].…”