ALBERT

Description: The evaluation of the seismic fragility of buildings is one key task of earthquake safety and loss assessment. Many research reports and papers have been published over the past four decades that deal with the vulnerability of buildings to ground motion caused by earthquakes in China. We first scrutinized 69 papers and theses studying building damage for earthquakes occurred in densely populated areas. They represent observations where macro-seismic intensities have been determined according to the Chinese Official Seismic Intensity Scale. From these many studies we derived the median fragility functions (dependent on intensity) for four damage limit states of two most widely distributed building types: masonry and reinforced concrete. We also inspected 18 publications that provide analytical fragility functions (dependent on PGA) for the same damage classes and building categories. Thus, a solid fragility database based on both intensity and PGA is established for seismic prone areas in mainland China. A comprehensive view of the problems posed by the evaluation of fragility for different building types is given. Necessary comparison with international projects with similar focus is conducted. Based on the newly collected fragility database, we propose a new approach in deriving intensity-PGA relation by using fragility as the bridge and reasonable intensity-PGA relations are developed. This novel approach may shed light on new thought in decreasing the scatter in traditional intensity-PGA relation development, i.e., by further classifying observed macro-seismic intensities and instrumental ground motions based on difference in building seismic resistance capability.

Description: In a cross-discipline study, we carried out an extensive literature review to increase understanding of vulnerability indicators used in both earthquake- and flood vulnerability assessments. We provide insights into potential improvements in both fields by identifying and comparing quantitative vulnerability indicators. Indicators have been categorised into physical- and social categories, and then, where possible, further subdivided into measurable and comparable indicators. Next, a selection of index- and curve based vulnerability models that use these indicators have been described, comparing several characteristics such as temporal- and spatial aspects. It appears that earthquake vulnerability methods traditionally have a strong focus on object-based physical attributes used in vulnerability curve-based models, while flood vulnerability studies focus more on indicators applied to aggregated land-use classes in curve-based models. Flood risk studies could be improved using approaches from earthquake studies, such as incorporating more detailed physical indicators, developing object-based physical vulnerability curve assessments and incorporating time-of-the-day based building occupation patterns. Likewise, earthquake assessments could learn from flood studies by refining their selection of social vulnerability indicators. Based on the lessons obtained in this study, we recommend future studies for exploring risk assessment methodologies cross-different hazard types.

Description: The evaluation of the seismic fragility of buildings is one key task of earthquake safety and loss assessment. Many research reports and papers have been published over the past four decades that deal with the vulnerability of buildings to ground motion caused by earthquakes in China. We scrutinize 69 papers with studies of building damage for magnitude≥4.7 events occurred in densely populated areas starting with the 1975 M7.5 Haicheng earthquake. They represent observations where macroseismic intensities have been determined according to the Chinese Official Seismic Intensity Scale. From these many studies we derive the most representative fragility functions (dependent on intensity) for 4 damage limit states of two most widely distributed building types: masonry and reinforced concrete. We also inspect 18 papers that provide analytical fragility curves (dependent on PGA) for the same damage classes and building categories. Finally, we check the consistency of fragilities as functions of intensity and PGA and derive corresponding relationships between macroseismic intensity and PGA. The intensity-PGA relationship developed in this study is fully compatible with results of previous research.