A project undertaken by TRANSIT NEW ZEALAND in conjunction with OPUS INTERNATIONAL CONSULTANTS...
-
Upload
jemimah-rice -
Category
Documents
-
view
213 -
download
0
Transcript of A project undertaken by TRANSIT NEW ZEALAND in conjunction with OPUS INTERNATIONAL CONSULTANTS...
A project undertaken by
TRANSIT NEW ZEALAND
in conjunction with OPUS INTERNATIONAL CONSULTANTS LIMITED
APEX PROJECT MANAGEMENT LIMITED
and
REGIONAL BRIDGE CONSULTANTS
S E I S M I C S E C U R I T Y O F S T A T E
H I G H W AY B R I D G E S I N
N E W Z E A L A N D
SCREENING & RETROFIT – PROGRESS SUMMARY
S E I S M I C S E C U R I T Y O F S T A T E
H I G H W AY B R I D G E S I N
N E W Z E A L A N D
SCREENING & RETROFIT – PROGRESS SUMMARY
2
OBJECTIVE & STATUS
• To identify bridges that justify a more detailed seismic assessment and, possibly, retrofitting
• Seismic screening completed
• Retrofitting underway
3
BACKGROUND
Project drivers:
• Experience from earthquakes – integrity of the roading network is vital
• Dramatic improvement in performance often achievable from simple measures, e.g. linkages
• Past practice - since 1933, bridges either monolithic or have spans interlinked
4
BACKGROUND
• Past retrofit policy – low cost seismic improvements in conjunction with work to raise service standards
• In early 1990s, 8 bridges in regions of higher seismicity retrofitted for linkages
5
BACKGROUND
• Wellington’s Thorndon Overbridge and the Auckland Harbour Bridge retrofitted
• A screening procedure was developed Refer 12th World Earthquake Conference (Chapman et al)
6
RISK ASSESSMENT
• Identification of structure vulnerabilities
• Classification of risk level for each risk event - likelihood & consequences
• likelihood derived from:
• peak ground acceleration causing risk event• seismicity of site
• consequences derived from:
• effect on safety• extent of traffic disruption
7
ECONOMIC RANKING INDICATOR (ERI)• For “high” and “significant” risks, an
“Economic Ranking Indicator” determined
• “ERI” was based on factors such as:• traffic volume
• duration & probability of disruption
• cost of traffic disruption
• cost of bridge damage (if significant)
• discounted cost (ROC) of retrofit
8
RANKING
• Ranking was based on factors such as:• Route priority
• Risk to Life
• ERI value
• Number of risk events
9
OUTCOME
• 3813 bridges & culverts screened• 2842 (75%) eliminated• 971 (25%) subjected to risk assessment• 381 (10%) “high” or “significant” risk level• 188 (5%) separately identified as having
linkage deficiencies• $850 per bridge for 2322 bridges
10
ASSESSING & RETROFITTING STRUCTURES• Top 50 ranked structures will be assessed
• Available specialist resources likely to constrain the timeframe for assessments
• Expenditure ~ $5M to ~$6M per annum
11
Bridge Seismic ScreeningStage 2
• Progress to date
– Linkage Retrofit
– Detailed Assessments
– Detail Design & Construction
• Programme Management
12
Progress to date• Linkage Retrofit
– P1 & P2 routes (130 comepleted)
• Detailed Assessments
– Re-prioritised 50 completed detail assessments
– On hold till first 25 bridges addressed
• Detail Design & Construction
– Retrofits complete 10
– Retrofits under construction 5
– Designs in progress 6
– Recommended for replacement 2
Programme Total P1 P2 P3
Detail Assessments 335 192 72 71
Linkages 173 92 45 36
13
Programme Management
• Delegated authority
• Project Team
– Rudolph/Gavin/John Wood/Howard Chapman
• Project Management Framework
– Basis of seismic design for existing bridges.
– Remaining life of structure & condition
– Mode of failure
– Performance indicators & risk profile
– Retrofit vs. replacement cost
– Route importance
– Bridge Design Statement