Design for Disassembly: Towards the resilient and sustainable ABC of the future

Sebastian Varela, Ph.D.

Structural Engineer III

Freese and Nichols Inc., Fort Worth, Texas

sebastian.varela@freese.com

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The modern seismic design philosophy for bridges

I-880 Oakland, 1989 Kobe, Japan 1995

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Engineered CementitiousComposite (ECC)

Prof. Victor Li, Univ. of Michigan

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ECC

Emerging Cu-Al-Mn (CAM) Shape Memory Alloy (SMA) Recently developed by

researchers in Japan

Easier to machine

Lower material cost

Still work in progress: low yield strength and hysteretic energy dissipation, production of large diameter bars

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Design for Disassembly (DfD)

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Extraction of

natural resources

Processing into

materials

Assembly into

bridges

Bridge use

Waste for

dumping

Demolition

Extraction of

natural resources

Processing into

materials

Assembly into

bridges

Bridge use

Waste for dumping

(minimal)

Disassembly

Reuse

Objectives

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Study viability of superelastic CAM SMA + ECC for bridge columns: 0.4% permanent drift @ 12% max drift in CIP col

Utilize advanced materials to mitigate bridge damage and permanent drift: full post-earthquake functionality with minimal or no repairs

Develop and test resilient and earthquake-resistant replaceable plastic hinge elements, connections, and bridge columns and systems

Determine the influence of reusing column components: DfD

Development of replaceable plastic hinges

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Nonlinear

Elastic –concrete-

filled CFRP tube

Elastic

Replaceable ECC plastic hinges

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State of CE-R after testing

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Key results

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Japan seismic design specifications limit permanent drift to 1%

Saiidi & Ardakani(2013): 1% can be safely accommodated by a wide range of RC bridges

Original

Reassembled

CE & CE-R: influence of disassembly and reassembly

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Original

Reassembled

2-span bridge models (bridge 1&2)

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CE bent

NR bent

NE bent

30’

30’

RC blocks Safety frame

Safety

columns

Shake table

Steel plates

PT deck

N

3’-7 1/2”

8’-3 1/2”

Assembly/disassembly time-lapse

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https://www.youtube.com/watch?v=RBwIRGUn52k

Bridge 2 test video

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https://www.youtube.com/watch?v=dsoYeRELhSo

Typical state of plastic hinges after testing bridge 2 (reassembled)

NE bent – North EPH

CE bent – South EPH 15

Permanent DriftsBridge 1 (original) – Run 4 (175% x DE):

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BentMaximum

drift (%)

Permanent

drift (%)

NE 5.60 0.26

NR 5.68 0.18

CE 5.58 0.07

Bridge 2 (reassembled) – Run 7 (260% x DE):

BentMaximum

drift (%)

Permanent

drift (%)

NE 9.95 0.26

NR 8.95 0.15

CE 7.90 0.08

Effect of disassembly and reassembly

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Conclusions Innovative concept for resilient and sustainable bridges

was successfully developed and tested dynamically on ¼ scale single column and 2-span bridge models

The advanced materials and detailing result in minimal damage and permanent column drifts: increased functionality after strong earthquakes

The new system facilitates reuse of components: mitigate environmental impact

The system has the potential of expediting and facilitating maintenance, repair, and upgrade of elements: ABC

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Thank you! Questions?

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http://wolfweb.unr.edu/homepage/saiidi/NSF-PFI/index.html