Earthquake Engineering for Next Generation Infrastructure

Transcription

1 Response to the Canterbury Earthquakes Earthquake Engineering for Next Generation Infrastructure Tim Sullivan Christchurch, NZ November, 2018

2 New Zealand s history of earthquakes prompted worldleading seismic design standards focussed on life-safety. Life-safety focus is not enough! 1931 Napier, New Zealand

3 Canterbury Earthquake Sequence Waimakariri River 4 DEC11 CBD 1 SEP10 2 FEB11 3 JUN11 20 km

4 Summary of Impacts from 22nd Feb 2011 Earthquake 185 fatalities CBD gone: ~ 70% of the buildings demolished Widespread liquefaction Residential properties: ~ 60,000 affected ~ 20,000 severely affected ~ 8,000 abandoned Pipe networks: ~ 700 km WW pipelines (loss/limited service) ~ one break per km PW pipes (4,000 km) Roads, bridges, Total economic loss: > 40b NZ dollars and social impacts?

5 Did buildings behave as engineers expected? What lessons are there for engineers to learn?

6 Pre-1970s buildings in Feb 2011 EQ Another example of a building suffering from short-column effect, as well as beam-column joint failures. New lesson for engineering? Figures from Weng et al. (2011)

7 SIMILAR COLUMN SHEAR FAILURES HAD BEEN REPORTED IN LITERATURE KOBE, 1995 New lesson for engineering? No NORTHRIDGE, 1994

8 Modern (post 1970s) buildings Photos show damage to the 22- storey pre-cast concrete frame building plastic hinges have formed at intended locations. New lesson for engineering? No part of design philosophy Figures from Weng et al. (2011)

9 22-storey building with steel EBF structure Structure was damaged at link locations, as could have been expected. New lesson for engineering? No part of design philosophy Photo from Clifton et. al. (2011)

10 What about non-structural elements? (Ceilings, Glazing, Partition Walls, Mechanical & Electrical Equipment, Contents, etc.)

11 Snapshots of damage to non-structural elements Damage to non-structural elements, such as partitions, ceilings, windows/cladding and piping, was very extensive. Source: Dhakal (2010) New lesson for engineering? No Source: Dhakal (2010)

12 Did buildings & infrastructure perform how building owners & the community expected?

13 The earthquake had very negative impacts While the number of lives lost was relatively limited compared to historical earthquakes of similar intensity there were many other negative impacts that included: Power cuts. Lack of water and wastewater services. Many roads were closed due to liquefaction. Central city closed. Around 10,000 houses requiring demolition and over 100,000 damaged. Many other negative impacts Huge service disruption = not good performance! Public wants more than just life-safety.

14 QuakeCoRE Mission: To place NZ at the worldwide forefront of earthquake disaster resilience through Creation of an enabling national collaboratory of researchers and stakeholders for development of new knowledge on the seismic response of the built environment and -Hosted at Univ of Canterbury Partners: UAuckland Victoria Univ Massey Univ Waikato Univ ResOrg GNS Science BRANZ Overarching goal a paradigm shift in design and operation of infrastructure components toward system-level optimisation for earthquake resilience. design of innovative technologies and decisionsupport tools enabling rapid recovery of NZ communities.

15 Flagship 4: Next-Generation Infrastructure Low-damage and repairable solutions Addressing the need to reduce damage/disruption Thrust 1: New low-damage systems Thrust 2: Reparability Thrust 3: Implementation

16 Recognised need for better communication Traditional descriptions of performance Repair Time? Repair Costs? Injuries or fatalities? (Figure by Ron Hamburger) Out of service for how long?!? Figure from SEAOC Vision 2000 document Building owner Member of public

17 What are we doing to improve the performance of buildings in the future? QuakeCoRE research efforts continue to develop: 1. New building systems that are less likely to be damaged. 2. Engineering tools and guidelines to enable (i) low-damage design solutions and (ii) improved assessment outcomes. 3. A new strategy for communicating performance/reparability. Repair time (days) Earthquake Intensity

18 1. Systems that are less likely to be damaged Development of low-damage RC structural systems Full scale 2-storey building shake-table testing underway (images courtesy of Rick Henry)

19 1. Systems that are less likely to be damaged Development of low-damage steel structural systems e.g. Steel EBF systems with replaceable links Replaceable link Traditional link 208 Barbadoes St 120 Hereford Street Photos courtesy of Greg MacRae

20 1. Systems that are less likely to be damaged Development of low-damage timber structural systems NMIT School of Arts and Design Structural Engineering Laboratory, UC Beatrice Tinsley Building, UC (photos courtesy of Minghao Li)

21 1. Systems that are less likely to be damaged Development of devices for low-damage systems Bulged-shaft type extrusion damper Energy dissipation! Turanga Library Images courtesy of Geoff Rodgers

22 Guidance documents 2. Tools and guidelines Development of documentation/data systems BIM Instrumentation

23 3. Process to help communicate likely performance Repair cost estimates can be used to compare systems Frequent EQ, = 5cm EBF repair: $0 Partition repair: $10000 Rare EQ, = 20cm EBF repair: $ Partition repair: $80000 Base Shear Force Roof displacement, Repair cost (normalised) Repair time (days) Relative reparability of different systems quantified. Earthquake Intensity Earthquake Intensity

24 What are the main challenges ahead for Flagship 4? In addition to structural systems and communication, challenge is to improve the seismic performance of: 1. Non-structural elements. 2. Residential buildings.

25 Understanding and addressing poor performance of non-structural elements Poor performance of nonstructural elements due to a number of reasons: Force fours times that expected by codes! Limitations in accuracy of our code design procedures Problems with procurement, installation & approvals process.

26 Understanding and addressing poor performance of non-structural elements Poor performance of nonstructural elements due to a number of reasons: Force fours times that expected by codes! Limitations in accuracy of our code design procedures Problems with procurement, installation & approvals process. Limitations with experimental testing facilities (ICC-ES AC-156 Qualification of Suspended Ceilings)

27 Illustrating development of low-damage non-structural systems Plasterboard partition walls Changes to detailing can double deformation capacity. Fire & acoustic requirements cannot just think earthquakes! Joints absorb deformation! Improvements required for full range of non-structural elements found in practice.

28 Residential buildings? New Zealand s residential buildings satisfy life-safety needs. However, residential = $16 billion of $40 billion total rebuild cost! Housing damage also has negative social impacts. NZ is in process of building 100s of thousands of new houses likely to be just as vulnerable! Figure from Wood et al. (2016)

29 What could we do to improve the performance of residential buildings? Make improvements to current building approach Develop innovative systems such as base-isolation Would it be worthwhile baseisolating NZ houses? Base Isolation of large buildings is not uncommon (Figure from Mayes R. in Naeim F. The Seismic Design Handbook, 2001) (Figure provided by Ezra Jampole)

30 How can we quantify potential benefits of new systems? Traditional House Loss = $11,300 $28,800 Base-Isolated House Loss = $6,400 - $10,000 QuakeCoRE F1: Magnitude 7.3 earthquake on Wairau fault (Animation kindly provided by Brendon Bradley and Karim Tarbali) Traditional House Loss = $10,000 -$26300 Base-Isolated House Loss = $6,000 - $9,800 Based on a house replacement price of $500,000 Base-isolated losses can even be zero if well engineered!

31 Conclusion Earthquake Engineering is vital for Next Generation Infrastructure to get our communities back up and running quickly! Thank you

32 Thank You

33 A list of historical earthquake disasters Year Lives lost 526 Antioch, Turkey 250, Damghan, Iran 200, Ardabil, Iran 150, Aleppo, Syria (M8.5) 230, Syria 100, Chihli, China (M7.8) 100, Shaanxi, China (M8.0) 830, Val di Noto (Sicily and Naples), Italy 150, Tabriz, Iran 200, Messina, Italy 100, Haiyuan, China (M8.5) 234, Kanto, Japan (M7.9) 105, Xining, China 200, Ashgabat, Russia (M7.3) 110, Tang Shan, China (M7.5) 240, Sumatra, Indonesia (M9.3) 260, Kashmir, Pakistan (M7.6) 79, Sichuan, China (M8.0) 68, Port-au-Prince, Haiti (M7.0) 316, Tohoku, Japan (M9.0) 16,000

34 Damage to lightly reinforced concrete walls New lesson for engineers? In a few cases yes.

35 New minimum reinforcement requirements in walls New limits based on testing and modelling Published in NZS 3101:2006-A3 Accepted into ACI 318:19

36 Modern (post 1970s) buildings CTV building, designed in 1986, collapsed in 22 nd February 2011 earthquake. Figure from Expert Panel Report - MBIE Expert panel report, prompted by the NZ government, identified multiple possible reasons for poor performance. However, report states that Collapse was almost certainly initiated by failure of a circular column when the lateral displacement of the building was more than the column could sustain.

37 Modern (post 1970s) buildings CTV building, designed in 1986, collapsed in 22 nd February 2011 earthquake. New lesson for engineering? Sadly No bad detailing Column drift capacities low not provided with ductile detailing