PSI - Issue 62

Alessandro Lipari et al. / Procedia Structural Integrity 62 (2024) 24–31 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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provides an overall structural condition indicator; it may be useful to benchmarking structures along a specific route or prioritizing an assessment programme. Then, the Structural Review process is conducted as follows: • The structure's year of construction is determined; • The load carrying capacity of the structure from design or assessment documentation is determined; • Where design or assessment documentation is insufficient to determine load carrying capacity, other sources of information can be reviewed to determine capacity, e.g. record drawings; • The Reviewer decides which of three scenarios best fits the structure and the information available: the scenarios are named B1 (assessment and outcome available), B2 (assessment done but no information available), and B3 (no assessment); • The Reviewer then applies the Risk Appraisal process defined in CS 451 to determine if an assessment is required. The Risk Appraisal is a numerical procedure based on the calculation of a risk score and a reliability score. The input parameters are reported in Table 2, along with the entries for the case studies presented in Section 3. The full numerical values and the equations to be used can be found in CS 451. Note that the derivation of the equations is not reported and there is no clear distinction between hazard, vulnerability and exposure as in the Italian guidelines.

Table 2. Input variables for determining the risk and reliability scores (numerical value associated to the entry) . Parameter Number of entry option Entries Bridge I

Bridge II

N/A

Width

Its value in m Its value in m Its value in m

10 m 90 m 25 m N/A

12 m

Length

N/A N/A

145.5 m

Maximum span

32 m N/A

D – Assessment availability (Scenario B1) 20 D – Assessment availability (Scenario B2) 16

Capacity: 38+, 26, 18, 7.5, 3 t; year (*)

Low, 1950-1975 (10 -6 )

Low, post-1990 (10 -8 )

Confidence level (low, medium, high; load capacity satisfactory); year (*)

D – Assessment availability (Scenario B3) 4

Year (*)

N/A

N/A

E – Interim measures including weight restriction

6

Weight limit: 3, 7.5, 18, 26 t; physical restraints for vehicles; not applicable

Not applicable (1)

Not applicable (1)

F – Current condition

3 2 2 3

Good, fair, poor

Poor ( 1000 ) Hidden ( 10 )

Fair (20)

G – Inspectability of critical elements

Critical elements not hidden, hidden

Not hidden (1)

H – Monitoring

In place, not in place

None (1)

None (1)

J – Change in condition since design/assessment

Significant, slight, none

Significant (500) Moderate (5) A road (3.5 & 10 6 ) Other route (0.1)

Slight (2)

K – Change in loading requirements since design/assessment

5

Significant, moderate, slight, no increase; abnormal vehicle loading Motorway/railway; A road; B road; other road/footpath/canal Motorway/railway; A road; B road; other road; other route, i.e. bridleway, canal, etc.

Moderate (5)

A road (3.5 & 10 6 ) Other road (0.15)

R1 & R3 – Route supported

4

R2 – Route crossed

5

(*) Year entries are: < 1950 or unknown, 1950-1975, 1976-1990, > 1990.

A decision matrix sets out the requirement for whether an assessment is required (Table 3). The matrix resolves the risk score and the reliability score to determine the need for assessment, noting that a higher risk and lower reliability scores are more favourable. Finally, it is worth mentioning that, whilst the outcome of the Structural Review may indicate that an assessment is not needed, the bridge manager may still require one to be undertaken.