Titel_SS06

The planning of inspections take basis in all the available information about the structure
including judgements based on engineering understanding and most importantly the
experience gained from assessments of other structures under similar conditions and concerns
the identification of inspection plans i.e. what to inspect, how to inspect, where to inspect and
how often to inspect. Even though inspections and maintenance activities may be an effective
means for controlling the degradation and maintaining the serviceability of the considered
structure and thus imply a potential benefit, they may also be associated with significant direct
costs. For this reason it is necessary to plan inspections and maintenance such that a balance is
achieved between the expected service life costs reduction and the direct economical
consequences implied by the inspection and maintenance activities themselves.

In addition to the inspection plans based on a "we know what we are searching for", a strategy
should also be followed where a number of inspections are planned with the sole purpose to
look for the unexpected. That is to look for failure states and deterioration mechanisms, which
have simply not been foreseen. Such conditions may be present due to unpredictable
irregularities in the execution of the structures or due to unreported accidents or misuse of the
structure.

Doubts

Phase 1

Site Visit

Study of Documents

Simple Checks

Phase 2

Investigations

Analysis

Further Inspections

Doubts

Confirmed

Do Nothing

no no

yes

yes yes

Compliance no

with codes and

regulations

Simple Repair

or Strengthening

Solve the Problem Phase 3Refined Limit State

Analysis

Laboratory Testing

Reliability assessment

Update Maintenance Economical dec. analysis

Strategy

Strengthening of

Structure

Redefine Use Demolition of structure

Figure 12.2: General adaptive approach for the assessment of structures.

Load-bearing capacity and durability of the particular structure is initially reassessed based on
simple structural analysis methods and readily accessible data. On this basis it is evaluated to
what extent the structure fails to comply with the given requirements. Furthermore, it is
identified how a refinement of the knowledge about the structure may best identify the
reason(s) for not complying with the given requirements. Such refinements may be based on
detailing of the structural analysis methods as well as on further collection of e.g. material
data.