On the variability of concrete strength as a source of irregularity in elevation for existing RC buildings: a case study

A proper assumption of the concrete strength is essential to model existing RC structures; their seismic performance, in fact, can be affected by the poor quality of materials, both in terms of low strength and high variability. This paper considers the effects of the variability of concrete strength within buildings. Due to the high variability of concrete strength, in fact, buildings can experience irregular seismic responses, both in plan and in elevation. This research investigates the effects of irregularity in elevation due to the strength variability of concrete in a case study, namely a four-storey RC framed building, designed for vertical loads only. The variability of the concrete strength has been evaluated on the basis of an extensive survey carried out by the REGIONE TOSCANA (Tuscany Regional Government) on a large sample of RC framed buildings. Special attention has been paid to the adequacy of current codes provisions (Eurocodes, FEMA) on how to quantify concrete strength.

[1]  Angelo Masi,et al.  ESTIMATION OF THE IN-SITU CONCRETE STRENGTH: PROVISIONS OF THE EUROPEAN AND ITALIAN SEISMIC CODES AND POSSIBLE IMPROVEMENTS , 2009 .

[2]  Mario De Stefano,et al.  The Effect of Common Irregularities on the Seismic Performance of Existing RC Framed Buildings , 2013 .

[3]  Giuseppe Quaranta,et al.  Hybrid technique for partial safety factors calibration , 2008 .

[4]  Gennaro Magliulo,et al.  Seismic performance of R/C frames with overstrength discontinuities in elevation , 2011, Bulletin of Earthquake Engineering.

[5]  M. Byers.  The confidence factor. , 2004, The Journal of the Michigan Dental Association.

[6]  Giorgio Monti,et al.  ASSESSMENT AND REDUCTION OF THE VULNERABILITY OF EXISTING REINFORCED CONCRETE BUILDINGS , 2009 .

[7]  M. De Stefano,et al.  Effect of the variability in plan of concrete mechanical properties on the seismic response of existing RC framed structures , 2012, Bulletin of Earthquake Engineering.

[8]  Giorgio Monti,et al.  Livelli di conoscenza e fattori di confidenza , 2007 .

[9]  P. Franchin,et al.  CONFIDENCE IN THE CONFIDENCE FACTOR , 2009 .

[10]  Angelo Masi,et al.  A parametric study on RC existing buildings to compare different analysis methods considered in the European seismic code (EC8-3) , 2008 .

[11]  Colorado Colorado,et al.  AMERICAN SOCIETY OF CIVIL ENGINEERS , 2010 .

[12]  Angelo D'Ambrisi,et al.  Seismic performance of irregular 3D RC frames , 2008 .

[13]  Michael N. Fardis,et al.  Seismic Design, Assessment and Retrofitting of Concrete Buildings , 2009 .

[14]  Paolo Franchin,et al.  Review of confidence factor in EC8-Part 3: a European code for seismic assessment of existing buildings , 2010 .

[15]  J. Mander,et al.  Theoretical stress strain model for confined concrete , 1988 .

[16]  Fatemeh Jalayer,et al.  Structural modeling uncertainties and their influence on seismic assessment of existing RC structures , 2010 .

[17]  Giuseppe Maddaloni,et al.  Comparison between non-linear dynamic analysis performed according to EC8 and elastic and non-linear static analyses , 2007 .