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Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Responsibility of the
engineer
(user of finite element
software)
Responsibility of the
supervisor
(manager)
Responsibility of the
organisation
(engineering
company)
Responsibility of the
software developer
(software
company)
It is the primary responsibility of the
engineer
(user of finite
element software) to create a computer model and to determine
the required parameters such that the model accurately
represents the real project and captures the phenomena that lead
to the quantities that need to be determined or interpreted from
the model (deformations, stresses, structural forces, flow, etc.).
This responsibility includes a proper validation of the model
and its components. It is also the responsibility of the engineer
to report any lack of data and the consequences thereof to his or
her supervisor or client.
It is the primary responsibility of the
supervisor
(manager)
of the modelling engineer or the project manager to check that
the model created and used by the project engineer is a reliable
model on the basis of which the project can be properly
analysed and/or designed with the required safety level. This
responsibility involves a check on how and to what extent the
model has been validated. For supervisors without advanced
numerical modelling experience themselves this may be
regarded as a difficult task, but it remains their responsibility.
This NAFEMS book is intended to provide at least some
guidelines for managers to discuss key elements of the
numerical modelling process with their engineers. Together
with his/her technical expertise and experience from other
projects, the supervisor should obtain a good impression of the
quality of the results obtained from a numerical model.
It is the primary responsibility of the organisation in which
numerical models are being used to create an environment in
which the importance and complexity of numerical modelling is
realised on all levels. If numerical modelling is part of their
activities, it should be included in their quality procedures. The
organisation should be structured such that there is sufficient
knowledge and room, not only to create numerical models but
also to validate models and to control the process from the early
stage of numerical modelling to the interpretation of the results
towards the geotechnical design. Just like any other subject,
numerical modelling is continuously evolving and new methods
become available. This requires organisations to invest in
facilities (literature, courses) to let their staff acquire the
necessary knowledge to remain up-to-date in order to use
numerical models with state-of-the-art technology in an
appropriate way.
It is the primary responsibility of the software developer to
produce software that has been sufficiently verified and that is
(ideally) free of programming errors. Moreover, it is also the
responsibility of the software developer to properly document
the models and methods that are implemented in the software
and make this documentation available to the user.
6 CONCLUSIONS
In this paper a summary is given of a NAFEMS document on
validating finite element models for geotechnical engineering
purposes (Brinkgreve, 2013). The document may be used by
engineers who actually build the numerical models and interpret
the results, as well as by supervisors and project managers who
are responsible for the overall design of a project. Validation, in
the context of this document, is the process to make plausible
that a finite element model includes the essential features for a
real situation to be analysed and its results are representative for
the situation in reality.
After defining validation and related terms, the paper first
describes sources of discrepancies between a real project and its
finite element model. Insight in the sources of discrepancies is
essential for a proper validation of the model and to reduce
modelling errors.
The main chapter is devoted to the various methods of
validation. The process of validation involves a validation of the
model as a whole, as well as a validation of the various model
components. Particular model components that need to be
validated are the geometry, the model boundaries, the material
(including soil) behaviour, the finite element mesh, the initial
conditions and the calculation phases. Results obtained from the
model should be checked against results obtained from other
analysis methods, design charts, experience, common practice
and measurements, if available.
The last chapter describes some non-technical issues related
with decisions, responsibilities and organisational issues to
control the quality of numerical modelling as part of the
geotechnical engineering and design process. In the first place it
emphasizes on the availability (or lack) of data and the need to
convince the client or project owner of the essence of good
quality soil investigation. In the second place, it highlights the
importance to spend time and money on education and training.
The latter is a common responsibility of the engineer and the
organization in which he or she is employed.
7 ACKNOWLEDGEMENTS
The authors would like to thank the NAFEMS Geotechnical
Committee for their feedback on the original document and for
their consent to publish this summarizing paper.
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