MINISTÈRE DES TRANSPORTS PRÉSENTATION POWERPOINT. REED M. ELLIS, Ph.D., P.Eng. Pièce MTQ-7

Transcription

1 MINISTÈRE DES TRANSPORTS PRÉSENTATION POWERPOINT REED M. ELLIS, Ph.D., P.Eng Pièce MTQ-7 Commissaires M e Pierre Marc Johnson, président M. Armand Couture, ing. M. Roger Nicolet, ing., M.Sc.

2 Comments on MTQ Bridge Inspection and Bridge Management Practices Reed M. Ellis 1

3 MTQ Bridge Inspection Practices In general, equal to or better than other jurisdictions Regular system of inspection Wide variety of structure types, varying condition Accepted methods of inspection Rating system with proven track record Policies and practices Training Supported by structures department with R&D Respected 2

4 MTQ Bridge Inspection Practices Perfect? There are areas which need improvement in every agency Have history of continuous improvement Developing new bridge management system to support and enhance practices New inspection manual will be severity and extent, condition state inspection similar to many other jurisdictions in Canada and US Consistent with new bridge management system 3

5 MTQ Bridge Inspection and other Manuals Many high quality comprehensive manuals Inspection Design Rehabilitation Construction Field pocket guide for bridge inspection Complete library of inspection forms for various bridge types Periodically updated and improved 4

6 General Inspection Similar to what is done in other jurisdictions Other provinces and US similar Detailed, routine, in-service safety inspection Not only piece of information used to make decision on bridge needs and timing of work Detailed condition survey Engineering analysis Financial lifecycle analysis Functional improvement needs 5

7 MTQ Bridge Inspection Training Training of inspectors not a contributing factor to the accident Given similar circumstances, inspectors in other jurisdictions would reach similar conclusions as MTQ inspectors because: inspection methods are similar what was visible would lead inspector to certain conclusions past experience points to certain conclusions 6

8 MTQ Bridge Inspection A bridge inspector: Can only inspect what he can see Can t inspect what he cannot see Generally assumes bridge was constructed in accordance with plans and specifications Unless something suggests unusual problem Majority of inspections are repeat inspections, updating findings of previous inspection 7

9 MTQ Bridge Inspection File review is usually brief Usually review drawings A bridge inspector, may make assumptions: Bridge in generally good condition, in service 35+ years, suggests stable structure Severe deterioration found in predictable areas only: soffit, bearing area, corbel Could not have known concrete quality was poor Generally doesn t review photos from past repairs 8

10 Cracking in Reinforced Concrete and Prestressed Concrete Previously discussed at length Bridge inspection manuals generally deal with cracking same way All concrete structures crack Diagonal cracks are generally more severe than other types of cracks Cracking in prestressed girders considered more severe than in plain reinforced concrete Various methods of defining cracking in concrete 9

11 Cracking in Reinforced Concrete and Prestressed Concrete Definitions from various Departments 10

12 OSIM Hairline <.1mm GOOD Narrow 0.1 to 0.3 mm GOOD Medium 0.3mm to 1.0mm FAIR Wide > 1.0mm POOR Condition States Good <0.3mm Light Fair 0.3mm to 1.0mm Medium Poor > 1.0mm Severe / Very Severe 11

13 Alberta Latest 2005 Hairline <.1mm <.1mm Narrow 0.1 to 0.3 mm 0.1 to 0.3 mm Medium 0.3mm to 0.7 mm 0.3mm to 1.0mm Wide > 0.7 mm > 1.0mm 12

14 NHI R/C Hairline <1.6mm Narrow 1.6mm to 3.2mm Medium 3.2mm to 4.8mm Wide >4.8mm 13

15 Hindsight is Consider inspector on site performing inspection say 1985, 1992, 2004 Observes deterioration in area affected by leaking deck joint Soffit of slab and p/s boxes, fascia=edge of slab A very common condition, countless spans in North America No reason to suspect concrete quality is poor inside the slab No reason to suspect reinforcing doesn t match plans Bridge in service 35+ years Inspector could not reasonably be expected to suspect anything unusual 14

16 Maintenance, Repair, Rehabilitation Strategies Many agencies do detailed condition surveys Once general needs are identified thru inspection Before work is ordered or tendered Gives opportunity to more accurately determine quantities for work, and fine tune timing Involves physical testing (eg CSE testing, cores, concrete compressive strength, deck delamination survey MTQ practice is similar to this Ontario, Alberta are other examples 15

17 Non-Destructive, Semi-Destructive and Destructive Testing Typically include Concrete core sampling CSE testing Delamination Survey Chloride penetration Cover measurements Concrete compressive strength Agencies rarely do all of these tests routinely without justification 16

18 Non-Destructive, Semi-Destructive and Destructive Testing MTQ similar to other jurisdictions Agencies rarely do all of these tests routinely without justification Eg. Coring - Only done when necessary Semi-destructive, can be destructive Cost Traffic interruptions Possible path for ingress of water and chlorides Agencies prefer to do materials testing at time of construction (concrete strength, air content, etc) 17

19 Miscellaneous Photographs 18

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24 Miscellaneous Photographs 23