Preliminary analysis of a soft‐storey mechanism after the 2009 L'Aquila earthquake

Observation of damage caused by the recent Abruzzo earthquake on April 6th 2009 showed how local interaction between infills and RC structures can lead to soft-storey mechanisms and brittle collapses. Results of the present case study are based on observed damage caused by the earthquake in the zone of Pettino. Analytical model based on simulated design procedure was built up and time history analyses were employed to verify the causes of the structural collapse, as highlighted by observed damage. This failure mechanism was investigated taking into consideration all components of the ground motion. Nonlinear behavior of brick masonry infills was taken into account and two parametric hypotheses for infill mechanical properties were considered, given the uncertainties that typically characterize these nonstructural elements. Nonlinear modeling of infills was made by a three-strut macro-model aimed at considering both local and global interaction between RC frame and infills. Seismic input was characterized by the real signal registered during the mainshock near the case-study structure. Different shear capacity models were considered in the assessment. Analytical results seem to confirm with good approximation the likely collapse scenario that damage observation highlighted; the lack of proper detailing in the columns made the local interaction between infills and RC columns and the strong vertical component of the ground motion to be the main causes of the brittle failure. Copyright © 2010 John Wiley & Sons, Ltd.

[1]  Halvard W. Birkeland,et al.  Connections in Precast Concrete Construction , 1966 .

[2]  Rj Mainstone,et al.  SUMMARY OF PAPER 7360. ON THE STIFFNESS AND STRENGTHS OF INFILLED FRAMES. , 1971 .

[3]  Gaetano Manfredi,et al.  A simulated design procedure for the assessment of seismic capacity of existing reinforced concrete buildings , 2010, Adv. Eng. Softw..

[4]  T. Paulay,et al.  Reinforced Concrete Structures , 1975 .

[5]  M. Fardis,et al.  Designer's guide to EN 1998-1 and en 1998-5 Eurocode 8: Design of structures for earthquake resistance; general rules, seismic actions, design rules for buildings, foundations and retaining structures/ M.Fardis[et al.] , 2005 .

[6]  Peter Fajfar,et al.  SOFT STOREY EFFECTS IN UNIFORMLY INFILLED REINFORCED CONCRETE FRAMES , 2001 .

[7]  Gerardo M. Verderame,et al.  Analytical investigation of elastic period of infilled RC MRF buildings , 2011 .

[8]  F. Colangelo.  Pseudo-dynamic seismic response of reinforced concrete frames infilled with non-structural brick masonry , 2005 .

[9]  F. Crisafulli.  Seismic behaviour of reinforced concrete structures with masonry infills , 1997 .

[10]  Julian J. Bommer,et al.  THE USE OF REAL EARTHQUAKE ACCELEROGRAMS AS INPUT TO DYNAMIC ANALYSIS , 2004 .

[11]  Jack P. Moehle,et al.  "BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318-11) AND COMMENTARY" , 2011 .

[12]  Wael W. El-Dakhakhni,et al.  THREE-STRUT MODEL FOR CONCRETE MASONRY-INFILLED STEEL FRAMES , 2003 .

[13]  J. F. Abel,et al.  A SIX-STRUT MODEL FOR NONLINEAR DYNAMIC ANALYSIS OF STEEL INFILLED FRAMEs , 2002 .

[14]  Dina D’Ayala,et al.  Push-over non linear analysis of infilled frames: realistic F.E models of panels and contact , 2008 .

[15]  H. Kaushik,et al.  A RATIONAL APPROACH TO ANALYTICAL MODELING OF MASONRY INFILLS IN REINFORCED CONCRETE FRAME BUILDINGS , 2008 .

[16]  M. R. Kianoush,et al.  Seismic Design of Reinforced Concrete Structures , 2001 .

[17]  Paolo Ricci,et al.  6th April 2009 L’Aquila earthquake, Italy: reinforced concrete building performance , 2011 .

[18]  S. Santini.  Experimental and numerical investigations on the seismic response of R.C. infilled frames and recommendations for code provisions , 1996 .

[19]  Rodolfo Puglia,et al.  Strong-motion parameters of the Mw=6.3 Abruzzo (Central Italy) earthquake , 2009 .

[20]  Eugenio Chioccarelli,et al.  Near‐source seismic demand and pulse‐like records: A discussion for L'Aquila earthquake , 2010 .

[21]  Peter Fajfar,et al.  Inelastic spectra for infilled reinforced concrete frames , 2004 .

[22]  Gian Michele Calvi,et al.  Experimental and numerical investigations on the seismic response of bridges and recommendations for code provisions , 1996 .

[23]  Peter Fajfar,et al.  Simplified non‐linear seismic analysis of infilled reinforced concrete frames , 2005 .

[24]  Iunio Iervolino,et al.  PRELIMINARY STUDY OF THE 2011 JAPAN EARTHQUAKE (M 9.0) GROUND MOTION RECORDS V1.01 , 2011 .

[25]  Stephen G. Buonopane,et al.  Pseudodynamic Testing of Masonry Infilled Reinforced Concrete Frame , 1999 .

[26]  A. Mattock,et al.  Shear Transfer in Reinforced Concrete , 1969 .