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Evidence of past earthquakes highlighted the seismic vulnerability to buildings due to soil liquefaction and lateral spreading phenomena. Damage to buildings on a liquefiable site, especially on a gently sloping site, can be severe. The liquefied soil can undergo permanent lateral ground displacements as large as several meters in some cases, which can be severely disastrous to buildings. Recent physical tests and effective stress analyses of nonlinear dynamic soil-structure interaction (SSI) proved that simplified empirical processes are often improper for evaluating liquefaction-induced building settlements. A better understanding of the SSI effects is also essential in cases where the underlying soil is susceptible to liquefaction. In this respect, the interaction of the earthquake excitation and ground failure (i.e. soil liquefaction and lateral spreading) for buildings considering SSI is investigated herein. Typical low-code reinforced concrete (RC) frame buildings of different heights with shallow spread footings on liquefiable level-ground or sloping soils subjected to ground shaking are considered. The direct SSI approach is implemented. Predictive relationships are established between the maximum normalized differential displacements (horizontal or settlement) and the permanent ground displacement (PGD) vector at the level of foundation for low-code RC frame buildings with shallow spread footings on soils with high liquefaction potential subjected to ground shaking. Finally, vulnerability is expressed in terms of fragility and vulnerability curves as well as in terms of fragility surfaces as a function of two intensity measures. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate whether existing generic fragility curves for various residential building typologies can be safely applied for the vulnerability assessment of school buildings. We select three representative typologies of actual reinforced concrete (RC) school buildings in Thessaloniki, Greece and we conduct a detailed fragility analysis combining field inspection and structural monitoring data to advanced numerical modeling. Building-specific fragility and vulnerability curves are derived for the three school buildings based on 3D incremental dynamic analysis (IDA) of the calibrated numerical models. The comparisons of the developed curves with generic ones showed their significant differences. [ABSTRACT FROM AUTHOR]

Harbours are crucial assets for the sustainment and development of human activities. The recent devastating tsunami events as well as the increasing number of people, structures and economic activities being exposed to tsunami hazards revealed the need for the estimation of the effects of tsunami wave on seaport structures. However, only a limited number of tools to estimate the potential impacts of tsunami are available until now. This study aims at developing analytical tsunami fragility functions for some representative typologies of seaport structures in Greece. In particular, low-code moment resisting frame (MRF) and dual reinforced concrete (RC) buildings of various heights, and a typical warehouse are considered in the analysis. A numerical investigation is performed considering different combinations of tsunami loads based on FEMA P646 (2008) [1] recommendations for gradually increasing tsunami inundation depths and for the various structure typologies. To minimize the uncertainties related to the definition of damage limit states, tsunami nonlinear static analyses are performed and appropriate tsunami capacity curves are derived for the considered structures. Structural limit states are defined on tsunami capacity curves in terms of threshold values of material strain. For the complete damage state, shear failure is also considered, since the collapse of structures may be caused by the occurrence of either a flexural or shear failure in structural components. Fragility curves are numerically calculated for the different damage states using nonlinear regression analysis. They could be used within a probabilistic risk assessment framework to assess the vulnerability of low-code RC buildings and typical warehouses exposed to tsunami hazard along European-Mediterranean and other regions of similar facilities worldwide. [ABSTRACT FROM AUTHOR]

While liquefaction has been widely recognized as being one of the principal earthquake hazards resulting to significant economic and societal losses, research in the vulnerability assessment and quantitative evaluation of the expected physical damages to building structures is rather limited. In this respect, this study aims at the vulnerability assessment of typical low-code reinforced concrete (RC) frame buildings of various heights with shallow flexible foundations subjected to differential permanent displacements due to liquefaction. Nonlinear static analyses are carried out for each considered structural typology assuming different gradually increasing differential displacement patterns applied as quasi-static loads directly at its supports (footings). Different damage mechanisms are examined including a flexural damage of the building members and a shear failure of the columns. The proposed methodology results to the development of lognormally distributed fragility curves for different structural damage states as a function of the liquefaction induced differential displacements. It is shown that the height of the structure as well as the existence or not of a horizontal component of the differential displacements represent key factors affecting the vulnerability assessment. Vulnerability curves are also constructed to assess the expected direct losses in normalised cost terms. The whole approach is illustrated through a specific example. [ABSTRACT FROM AUTHOR]

• Framework to assess the fragility of RC buildings to ground shaking and liquefaction. • Nonlinear incremental dynamic analysis under effective stresses of the soil. • Consideration of soil-structure interaction and soil liquefaction potential. • Conventional fragility curves for buildings due to ground shaking and liquefaction. • Fragility surfaces for buildings due to combined ground shaking and liquefaction. The recent strong seismic events have demonstrated that most damage to coastal buildings is often associated with liquefaction effects. The occurrence of earthquake-induced ground shaking and liquefaction may be dramatic for buildings and poses a considerable threat to people. However, the influence of the simultaneous action of ground shaking and soil liquefaction considering soil-structure interaction (SSI) effects on the structural behaviour of buildings has not been adequately studied yet. In this respect, we propose a methodology for the fragility assessment of non-ductile reinforced concrete (RC) moment-resisting frame buildings exposed to combined ground shaking and soil liquefaction, based on a fully coupled numerical approach considering SSI. A fully coupled (u-P) formulation is employed, which can capture in cohesionless soils the permanent shear-strain accumulation during dilation and soil liquefaction. Two-dimensional incremental dynamic analysis of the nonlinear SSI systems is conducted for the estimation of the building response. The proposed methodology yields either conventional fragility curves, or coupled fragility surfaces, which are a function of more than one intensity measures and provide useful and important information for an integrated fragility assessment. It is shown that the height of the building resting on liquefiable soil may significantly affect its vulnerability to combined ground shaking and soil liquefaction, with the non-ductile low-rise RC frame buildings suffering more structural damages compared to the mid- and high-rise ones. Also, the high-rise buildings, even susceptible to liquefaction, do not sustain severe structural damages but only sink or tilt. The proposed fragility models can be adapted to estimate the risk of typical non-ductile RC frame buildings exposed to ground shaking and soil liquefaction. [ABSTRACT FROM AUTHOR]