Civil Engineering Reference
In-Depth Information
3.
Establishing the minimum requirements defined in stand-
ards or codes.
5.6 The structural and service life design,
construction and through-life care processes
5.6.1 Introduction
Service life design should be an integral part of the overall
structural design process, rather than a stand-alone 'bolt-on'
carried out subsequently as part of a quality assurance pro-
cess. However expressed, some form of required service life is
essential to enable alternative design options for meeting it to
be evaluated at the conceptual and detailed design stages.
Figure 5.18
presents a greatly simplified representation of
the main stages in a service life design approach, and its broad
interactions with structural design. The general flow in the pro-
cess is from the top of the diagram to the bottom, but it also
portrays lateral interactions between the structural and dur-
ability design processes. Most important is the feedback loop
that seeks to recognise the implications of certain decisions
4.
Choosing preliminary concrete mix design/protection
measures.
5.
Making preliminary predictions of the anticipated service
life on the basis of the defined environmental conditions
and various concrete mix or protection combinations.
6.
Comparing the predicted service life with that required.
7.
Making any design modifications required and defining
any additional protection measures required to achieve the
target service life.
8.
Establishing a 'shortlist' of additional measures options,
if this is appropriate, considering cost and environmental
impact implications.
9.
Selecting a suitable combination of measures for the
required (target) design service life.
Owner's brief
Structural design
Service life design
Assessment of physical loads and
associated actions
Assessment of environmental loads
and circumstances
Preliminary structural design
Conceptual service life design
Detailed structural design
Evaluation of applied loads and
actions, selection of appropriate
member sizes, etc. to achieve required
structural capacity, robustness, etc.
Detailed service life design
Incorporating appropriate detailing and
durability design features.
Uses service life forecasting and
enhancements where appropriate
Detailing of structure and
specification definition
Assessment of execution issues
affecting service life design
Execution strategy for design
Assessment of in-use issues
affecting service life design
Strategy for through-life care
Figure 5.18
Simplified service life design procedure (Nolan
et al
., 2006)
