Effect of soil–structure interaction and spatial variability of ground motion on seismic risk assessment of bridges - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 604

by the oversimplifying approach of the code-based, earthquake record
selection procedures. REXEL (Iervolino and Galasso, 2010; Iervolino et al. ,
2009) is the fi rst software introduced for this purpose and facilitates the
search for suites of waveforms compatible with target spectra that are either
user defi ned or automatically generated according to Eurocode 8 and the
recently issued Italian seismic code. An alternative web-based software for
earthquake record selection is SelEQ (Dias, 2010) offering various fi ltering
options. More recently, a MATLAB-based software ISSARS (Integrated
System for Structural Analysis and Record Selection) has been developed
(Katsanos et al. , 2011) connecting through the selection engine Internet to
the aforementioned PEER-NGA ground motion database, to form suites
of records that comply with specifi c criteria. These suites of records are
then ranked based on their compatibility with the design spectrum by
maintaining the resulting level of dispersion of structural response quanti-
ties as low as possible. This is made feasible by using the Applications
Programming Interface of the fi nite element program SAP2000 (C&S,
2008) to run numerical analyses at the background and quantify the dis-
crepancy of structural response as a part of the earthquake record selection
process.
Generation of synthetic and artifi cial earthquake motion tools.
Design and assessment of extended structures often require the generation
of spatially variable earthquake motions to be used as multiple-support
inputs. A review of the methods most widely used can be found in Zerva
and Zervas (2002). Site effects and SSI can also be accounted for in the
signal generation process (Sextos et al. , 2003a). The use of existing, appro-
priately modulated, records to prescribed target earthquake characteristics
(nonstationary in amplitude, frequency content, earthquake magnitude,
local site conditions, duration, etc.) is another advantageous alternative
(Liao and Zerva, 2006). Wavelets analysis, a powerful technique which uses
various mother wavelets, usually different from sinusoidal function like
Fourier method, and then adjusts the wavelet by shifting and scaling, thus
achieving an effective way of characterizing a non-stationary time history
data, has also been used for generating spectrum compatible synthetic
accelerograms (Giaralis and Spanos, 2009; Mukherjee and Gupta, 2002) for
investigating the seismic response of both structures (Giaralis and Spanos,
2010) and geotechnical systems (Haigh et al. , 2002).
22.4.2 Rotational component of the foundation response:
Kinematic interaction between pile and soil, apart from fi ltering the high-
frequency content of the incident seismic waves, induces rotations at the