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A multi-purpose and multi-scale tool for the seismic vulnerability and risk classification of critical buildings, such as schools, is proposed for pre- and post-event decision-making to mitigate the risk and reduce losses. The herein proposed "RiskSchools" system, is capable of performing the seismic risk assessment and grading of school buildings at various scales (district, municipality, region etc.), using (a) a pre-seismic rapid visual screening and grading of the school buildings in different vulnerability-risk classes and (b) a seismic risk assessment of the school buildings population, applying probabilistic or scenario-based methods for the seismic hazard and analytical methods for the vulnerability and risk assessment, also leading to a grading of the buildings' risk. The results of the two approaches are compared and combined through a flexible and adaptable expert elicitation scheme to provide a final classification of the seismic risk of the school buildings in the scale of interest and a prioritization scheme with respect to the need for seismic upgrade and retrofitting. The RiskSchools system consists of a powerful, state-of-the-art, user-friendly, and easy-to-use smartphone application for the compilation of the inventory and the rapid visual screening, and a project-dedicated multi-purpose webGIS platform for the seismic vulnerability and risk classification of school buildings at any scale. Although it is initially developed and applied to the school building stock of the Region of Central Macedonia in Greece, it has been specifically designed to be easily applied to other regions of Greece and worldwide and adapted to other critical buildings, like health care and hospital buildings. The ultimate scope of the RiskSchools System is to allow for the optimal design of decision-making procedures in support of disaster management to enhance critical buildings resilience. [ABSTRACT FROM AUTHOR]

Recent strong seismic events have highlighted the high vulnerability of port facilities resulting in significant physical damages and important socio-economic losses. The most widespread source of seismic damage to port structures is often not related to the ground shaking itself but to the induced phenomena principally associated to the liquefaction of loose, saturated soils that often prevails at coastal areas. In this context, this study aims at the investigation of the influence of soil liquefaction on the seismic performance and vulnerability of typical port gravity quay walls. Different gravity quay wall configurations are examined with varying base width/height ratios. Two-dimensional incremental dynamic analysis is conducted for the soil-quay wall system, under effective stresses using OpenSees software, considering a representative set of fifteen real ground motion records as input ground motion at the bedrock. Two numerical approaches are applied to investigate the effect of liquefaction on its seismic performance and vulnerability assessment: the first one without considering liquefaction, while the second considers the effects of liquefaction. The damage measure is defined in terms of the normalized seaward displacement. Fragility and vulnerability curves are finally derived in terms of different intensity measures and compared with available literature curves. Results show the important role of liquefaction in increasing the seismic vulnerability of the typical port quay wall. [ABSTRACT FROM AUTHOR]

Liquefaction constitutes the most common source of seismic damage to buildings resting on saturated soils. Soil-structure interaction (SSI) may also significantly affect the seismic response of structures, modifying their dynamic characteristics and the seismic response at the foundation level. Although progress has been made on the investigation of the influence of soil liquefaction and SSI on the structural response, studies combining both phenomena are very limited. To bridge this gap, we investigate the integrated influence of both liquefaction and SSI on the seismic response and vulnerability of low-code reinforced concrete (RC) moment resisting frame buildings. A two-storey non-ductile RC frame building is adopted as reference. The following numerical models are developed: (1) a fixed-base structure subjected to free-field (FF) motion neglecting liquefaction (and SSI); (2) a fixed-base structure subjected to FF motion allowing liquefaction; (3) a flexible-base structure (i.e. including SSI) resting on soil subjected to outcrop bedrock motion neglecting liquefaction; (4) a flexible-base structure resting on soil subjected to outcrop bedrock motion allowing liquefaction. Conducting nonlinear incremental dynamic analysis for the above-described configurations, we derive seismic fragility curves considering (or not) SSI and/or liquefaction effects for different damage limit states through statistical correlation of the calculated engineering demand parameter with appropriate intensity measures. We also generate vulnerability curves to quantify the expected structural losses. Results show the substantive role of liquefaction and SSI in altering the seismic fragility and vulnerability of non-ductile low-rise RC frame buildings. [ABSTRACT FROM AUTHOR]

Recent natural disasters that seriously affected critical infrastructure (CI) with significant socio-economic losses and impact revealed the need for the development of reliable methodologies for vulnerability and risk assessment. In this paper, a risk-based multi-level stress test method that has been recently proposed, aimed at enhancing procedures for evaluation of the risk of critical non-nuclear infrastructure systems against natural hazards, is specified and applied to six key representative CIs in Europe, exposed to variant hazards. The following CIs are considered: an oil refinery and petrochemical plant in Milazzo, Italy, a conceptual alpine earth-fill dam in Switzerland, the Baku–Tbilisi–Ceyhan pipeline in Turkey, part of the Gasunie national gas storage and distribution network in the Netherlands, the port infrastructure of Thessaloniki, Greece, and an industrial district in the region of Tuscany, Italy. The six case studies are presented following the workflow of the stress test framework comprised of four phases: pre-assessment phase, assessment phase, decision phase and report phase. First, the goals, the method, the time frame and the appropriate stress test level to apply are defined. Then, the stress test is performed at component and system levels and the outcomes are checked and compared to risk acceptance criteria. A stress test grade is assigned, and the global outcome is determined by employing a grading system. Finally, critical components and events and risk mitigation strategies are formulated and reported to stakeholders and authorities. [ABSTRACT FROM AUTHOR]

Greek classical temples constitute monuments of great historical and architectural value. The majority of them remain nowadays as free-standing multi-drum or monolithic columns or portals. Their present typology, in addition to their slenderness, render their response to seismic ground shaking quite distinct compared to that of modern structures. Rocking and/or sliding of the drums along their interfaces are the main modes of response under seismic loading. In this study, the seismic response of classical multi-drum columns is investigated by means of rigorous numerical analysis. An Ionic multi-drum column that has recently been restored at the Akropolis of Lindos in Rhodes, Greece, is used as a case study. The numerical analyses are performed using the finite element code ABAQUS. Numerical modelling is validated with a series of shaking table tests that were performed on a scaled multi-drum model column. Additional analyses are conducted by bonding perfectly the structural elements of the column, to investigate the seismic response of free-standing monolithic columns and compare with multi-drum columns of the same geometry. Through the presentation of representative results, critical parameters that affect the seismic response of this type of structures, including the amplitude and frequency content of the applied base excitation, the effect of uniaxial or multiaxial excitation and the interface characteristics, are highlighted and discussed. Particular emphasis is given on the stresses developed along the interfaces during shaking. The structural performance and overall stability of both the multi-drum and monolithic columns are investigated in terms of the maximum displacement of the capital against various intensity measures of the base excitation. The study contributes towards the improvement of the knowledge of the seismic performance of free standing rocking systems, such as the classical columns. [ABSTRACT FROM AUTHOR]