Structural resistance of reinforced concrete buildings under pyroclastic £ows: a study of the Vesuvian area S.M. Petrazzuoli, G. Zuccaro  Dept. ‘Scienza delle Costruzioni’, University of Naples ‘Federico II’, Via Claudio 21, 80125 Naples, Italy Received 1 May 2002; accepted 21 April 2003 Abstract The analysis of the effects of pyroclastic flows on humans and on buildings represents the main tool to define the boundary of the most hazardous area around an active volcano such as Somma^Vesuvius. Estimation of the lateral pressure on buildings derived from analogies with the damages observed after a nuclear explosion [Valentine (1998) J. Volcanol. Geotherm. Res. 87, 117^140] lead to pressure values and/or structural resistance which are not realistic (too high). Recent evidence [Baxter (2000) Human and Structural Vulnerability Assessment for Emergency Planning in a Future Eruption of Vesuvius. Final Report EC Project ENV4-CT98-0699; Young et al. (1997) EOS, Trans. Am. Geophys. Union, 78, 401] have shown that beyond 2^3 km from the vent, even after a great eruption, resistance to collapse of buildings affected by a pyroclastic flow is still possible. Neri et al. [(2000) Numerical simulation of pyroclastic flows. In: Human and Human and Structural Vulnerability Assessment for Emergency Planning in a Future Eruption of Vesuvius. Final Report EC Project ENV4-CT98-0699], by means of a numerical model of a collapsingcolumn,showthatthepeakoverpressuresofthepyroclasticflowsrangefrom1to2kPaatadistancefrom the vent of about 4^5 km, where important historical centres of the Vesuvian area are located. A detailed analysis of urban settlement of the area [Cherubini et al. (2001) Vulnerabilita’ Sismica dell’Area Vesuviana. Gruppo Nazionale per la Difesa dai Terremoti, CNR, Roma] has shown that most of the people live in reinforced concrete (r.c.) structures, not designed to resist horizontal seismic actions. The present work is aimed at analyzing the collapse limit load of r.c. structures to horizontal pressure for different structural design typologies (strong aseismic, weak aseismic, strongnon-aseismic,weaknon-aseismic).Thesimulationsperformedhavealsotakenintoaccountthespecificfeatures of the r.c. structures of the area (local building practice). The limits of resistance for each typology, in case of regular and irregular buildings, are provided. Such limits of resistance are in good agreement with the literature data coming from collapse simulation of buildings under seismic actions. ß 2003 Elsevier B.V. All rights reserved. Keywords: structural damage; reinforced concrete; pyroclastic £ow 1. Introduction The existence around the world of wide urban settlements nearby active volcanoes, like in the Neapolitan area (Vesuvius and Phlegraean Field) of Italy, Sakurajima of Japan, and Popocateptl of Mexico, emphasises the importance of estimating the e¡ects of pyroclastic £ows on buildings, in order to acquire useful indications for emergency 0377-0273/03/$ ^ see front matter ß 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0377-0273(03)00407-4 * Corresponding author. Fax: +39-081-768-3332. E-mail address: zuccaro@unina.it (G. Zuccaro). VOLGEO 3035 6-4-04 Cyaan Magenta Geel Zwart Journal of Volcanology and Geothermal Research 133 (2004) 353^367 R Available online at www.sciencedirect.com www.elsevier.com/locate/jvolgeores