Ground motion selection for seismic risk analysis of civil infrastructure - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 106

4.9 Software implementations

Despite the fact that many studies have highlighted the differences between
the uniform hazard spectra (UHS) and individual earthquake scenarios, and
therefore its inappropriateness for use in ground motion selection (see
Bradley, 2010a, and references therein), it remains the most common 'target'
for selecting ground motion records, most likely due to its presence in
seismic design codes. The reluctance of the earthquake engineering profes-
sion to depart from UHS-based selection of ground motions is arguably,
because of its simplicity to implement relative to methodologies with
sounder theoretical bases.
In order to improve the ease with which the GCIM approach can be
utilized, therefore increasing its potential for uptake in earthquake engi-
neering practice, the method was implemented in the open-source software,
OpenSHA (Bradley, 2010b; Field et al. , 2003). OpenSHA is an object-
oriented, web- and GUI-enabled and freely available software developed
as a joint venture between SCEC and USGS (www.opensha.org/). A
MATLAB implementation of the ground motion selection algorithm (using
the resulting output fi le from the aforementioned OpenSHA implementa-
tion) used for obtaining the results in this manuscript is available from the
author upon request. The algorithm is computationally effi cient, taking
approximately 1 s to obtain a set of 30 recorded ground motions (on a 4 GB
RAM 1.40 GHz dual core laptop computer).

4.10 Conclusions and future trends
As with any emerging method, the successful adoption of the proposed
ground motion select methodology requires both: (i) demonstration of its
capability and (ii) its ease of application in a practical environment. This
chapter, as well as the previously presented material in Bradley (2010a,
2012a, 2012b), essentially provide the underlying theoretical details and
salient features of the methodology, as well as its application to a single case
study. However, clearly further case studies using the methodology are war-
ranted for further demonstration of the benefi ts relative to alternative
methodologies.
The ease of application in a practical environment requires both ade-
quate software in which the methodology is implemented, as well as the
availability of the required input information for the particular problems
under consideration. As noted in the previous section, in an effort to address
the fi rst point, GCIM distributions and random realizations for use in the
proposed methodology have been implemented in the open-source soft-
ware OpenSHA, while a MATLAB version of the ground motion selection
aspects of the methodology is also available. It is intended to implement