Civil Engineering Reference
In-Depth Information
Bearing
Stub axle
Resultant was much further
away from the support than
was assumed
Assumed position of
resultant of forces on axle
Figure 6.5 Stub axle bearing for Ramsgate Walkway showing positions of resultant force
Model
validation
Results
verification
Activity
Outcome
Control
Deine the
requirements
Requirements
statement
Assess the
requirements
Requirements
assessment
Checking
model
Deine the model
Description of the
model
Validate the model
Review
Modelling
process
review
Do the calculations
Results
Verify the results
Software
assessment
Results
interpretation
Table 6.2 Basic process components and controls for analysis
modelling
Sensititivity
analysis
Competence
assessment
6.6.3 Analysis modelling review
6.6.3.1 Modelling review activities
A modelling review is the sum of all the activities that seek to
identify faults in the modelling process.
Figure 6.6
shows a
range of modelling review activities.
Figure 6.6 Activities in a modelling process review
It is good practice to prepare a validation analysis for non-
standard contexts. Ways of presenting these are given in Insti-
tution of Structural Engineers (2002) and MacLeod (2005).
While having an initial validation exercise is very important,
validation information can emerge from the results especially
from sensitivity analysis. A constant lookout for information
that will assist the validation should be maintained.
Questions for validation include:
6.6.3.2 Requirements assessment
While the requirements for a structural analysis are normally
evident it is worthwhile to reflect on them and to draw up a
requirements statement for complex or non-standard contexts.
Questions for requirements assessment include:
1.
Stresses and internal forces
: Have the locations and tar-
get accuracy been identified? Has the distinction between
local and resultant stresses been clearly identified?
1.
Assumptions
: Have all the assumptions for the model been
identified?
2.
Displacements
: Where do the displacements need to be
defined and to what accuracy?
2.
Validation information
: Is all relevant validation informa-
tion available?
3.
Natural frequencies and mode shapes
: What range of nat-
ural frequencies need to be considered?
3.
Test results
: Are there test results available to support the
validation?
4.
Fundamental requirements assessment question
: Have all
required performance issues been identified and included
in the requirements statement?
4.
Fundamental validation question
: Is the model capable of
satisfying the requirements?
6.6.3.3 Model validation
Model validation
is the process of ascertaining whether the
model is capable of meeting the requirements.
A model validation is carried out by listing all the assumptions
made for the model. To do this one needs
validation information
,
i.e. information which discusses the applicability of assump-
tions. Such information is not readily available in conventional
texts on structural analysis - but see MacLeod (2005).
6.6.3.4 Results verification
Results verification is the process of seeking to ensure that the
model has been correctly implemented.
Both formal and informal strategies should be used to seek
to identify faults in the implementation of the model. A formal
checklist can be used but also regular quantitative and qualita-
tive checks should be carried out.
