PSI - Issue 64

Chris Hendy et al. / Procedia Structural Integrity 64 (2024) 206–213 Hendy C/ Structural Integrity Procedia 00 (2019) 000 – 000

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7. Proposed management of risk for over-utilisations at SLS Where this ULS approach is used an initial investigation should be undertaken to a sample of hinges at the time of assessment, which will remove the hinge sealant and investigate the throat itself for any evidence of cracking associated with over-utilisations at SLS. The sealant should be reinstated following the investigations. It is important that the reinstatement to the hinge throat matches the existing section to not change the behaviour of the hinge. Ongoing visual inspection of the hinges as part of the inspection regime will then be able to inspect: i. the integrity of the hinge sealant, a change in which would lead to a change in risk of water / contaminant ingress to the hinge throat. Where the hinge sealant is damaged it would be expected that a renewal would be undertaken in line with the regular maintenance for structures. A Special Inspection might be recommended at the time of sealant replacement to visually inspect the hinge if concerns exist at the time of initial inspection that the further deterioration is likely to have occurred to the hinge throat from water ingress observed. ii. that no tensile cracking has occurred to the concrete in the adjacent end block to the hinge to ensure that the ULS validation for end block splitting remains appropriate. This should be stated in the Assessment Report / Maintenance Manual on completion of the works. 8. Experience from previous hinge inspections The use of the assessment approach in this paper on the A465 Section 5&6 scheme required several hinges to be inspected in accordance with section 7 above. All of these hinges had relatively low axial force through the hinge throat. The inspection consisted of half-cell and chloride test panels along the sections above and below the hinge to identify the location most likely to be corroding. Sealant was then removed at the critical location, and hinges inspected for condition initially. Results of the 9 No. Hinge Locations that have been inspected showed: i. 3 No. had been exposed to leaking deck drainage water. a. One location had complete reinforcement section loss, but no spalling or cracking to hinge throat (Fig. 3); b. One location had 10% section loss with no spalling or section loss; c. The other location had no hinge reinforcement section loss or visible spalling or cracking, although some section loss to bursting reinforcement was revealed; ii. The other 6 locations were dry and sealant was in good condition. No hinge reinforcement section loss or visible spalling or cracking (Fig. 4) It was noted that the backing board behind the sealant on the A465 hinges was an asbestos-containing material requiring additional precautions. Asbestos could be present at other hinges requiring inspection so care needs to be taken. Limits on the width of hinge throat broken back to inspect reinforcement condition need to be clearly stated along with action to take if exceeded (ie. closure until repaired). Reinstating the hinge throat to exactly the current hinge throat also needs to be highlighted, requiring a method statement prior to start of works showing how this will be achieved.