Presented by

Special Considerations

Bruce C. Bigelow, PhD Project Element Manager

Site Infrastructure, Enclosure, and Facilities (SEF)

This presentation is provided for general information only. GMTO makes no representations about the information contained herein. Proposers are directed to build their proposals based on the information and requirements contained in the eventual A&E Request for Proposal.

Special Considerations

GMT Status in Chile

Building Codes

Seismic Review

Seismic Considerations

Agenda

GMT Status in Chile

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International observatories in Chile, including the GMTO, operate under a set of laws that exempt them from the normal permitting and approval processes:

Decree N° 18. January 04, 1964 - Enacts agreement between the government of Chile and the European Organization for Astronomical Research of the Southern Hemisphere (ESO), for the establishment of an astronomical observatory in Chile. Decree N° 74. March 26, 2014 – Grants prerogatives and facilitations to GMTO Corporation. Decree N° 223. February 24, 2015 – Declares that The GMTO Corporation and its personnel will have exemptions related to the construction, installation, maintenance and operation in Chile of the astronomical scientific project called "Giant Magellan Telescope" or "GMT Telescope".

GMTO, and the enclosure A&E, will not be required to receive building permits, inspections, and approvals from local governing authorities

GMTO is required to comply with Chilean regulations regarding labor, health, and safety

The GMT observatory is being designed and constructed to codes and standards appropriate to the site in Chile, ensuring life-safety and seismic integrity, while also delivering cost effective, constructable, and maintainable facilities for the life of the observatory.

The GMT approach to building codes and standards:

Designs must comply with laws, codes, and regulations in Chile, and in particular, the Normas Chilenas (NCh)

The enclosure, pier, and seismic isolation structural systems shall be designed according to the Uniform Facilities Criteria (UFC 3-301-02, 3 March 2020, an enhancement of the 2018 IBC and ASCE 7-16), and to the Normas Chilenas where more restrictive.

The enclosure, pier, and seismic isolation systems shall be designed according to the NFPA and NEC codes for fire, life-safety, and electrical systems, and to the Normas Chilenas where more restrictive.

GMT Use of Codes and Standards – (1)

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We welcome proposer feedback and guidance on use of local and alternative codes and standards, which may be more appropriate and will lead to greater value for GMTO with respect to safety, quality, cost, schedule, and maintainability.

We expect that for codes and standards purposes:

▪ The lower enclosure is classified as a “building”

▪ The upper enclosure is classified as an “industrial structure” or “machinery enclosure”

GMT Use of Codes and Standards – (2)

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Seismic Review Considerations (1)

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According to Chilean Law #19.748 (2001) and NCh 2369 Of 2003, “Seismic Design for

Structures and Industrial Facilities”, seismically designed structures shall be reviewed and

certified by an Independent Seismic Reviewer registered in the Structural Reviewers Registry

(administered by the Chilean Housing and Urban Development Ministry - MINVU).

While GMTO status in Chile may exempt the project from the seismic review process, GMTO

will require the Designer to subject the enclosure and related structural designs to the MINVU

Independent Seismic Review process, and to deliver construction documents that have been so

reviewed and certified.

Seismic Review Considerations (2)

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For typical buildings in Chile (concrete, steel, residential):

▪ It is mandatory

▪ Must select a Seismic Reviewer

from the MINVU's list

▪ Reviewers are organized in the

list according to their capabilities

and the structure's complexity

For the GMT Observatory:

▪ The A&E will subject the

enclosure structural designs to

an independent review

Independent

Seismic Review

Seismic Isolator

Reviews

Seismic Review

timeframe

Chilean Code NCh 2745

▪ The design should be reviewed by

the Seismic Reviewer

▪ Isolator fabrication must also be

reviewed and tested

▪ Following a high Mercalli Intensity

earthquake (VI+) or acceleration

greater than 0.02 g

▪ An inspection of the isolator

is warranted as determined

by the design engineer

▪ The Seismic Isolation

System design must provide

a means for in situ

inspection of the isolator

working surfaces

The Reviewer needs to have the full design for the review

▪ Drawings

▪ Specifications

▪ Calculations (some

reviewers do not require

them)

After the full design is received and depending on the complexity, a 2+ months review process can be expected

Special Seismic Considerations

Very high seismic activity at the GMT site

~400 earthquakes in the last 5 years

An Mw 5.8 event, 50 km from the GMT Site, occurred on 10/28/2020 (shown in yellow)

The GMT site experiences an average of 6 earthquakes per month!

9

Data from: www.usgs.gov30

318

40

8

0

50

100

150

200

250

300

350

[3.0 - 4.0) Mw [4.0 - 5.0) Mw [5.0 - 6.0) Mw [6.0 - 7.0) Mw

Earthquakes magnitudes and frequencieslast 5 years - Near GMT Site

10 December 2020 Special Considerations

Special Seismic Considerations

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GMT will be among the first generation of telescopes to use a seismic isolation system (SIS)

Seismic isolation of a telescope creates unique demands on the isolation system

▪Sufficient stiffness/rigidity for normal operations (vertical and lateral)

▪Appropriate stroke, friction, and damping performance for seismic protection

▪Visual inspections are required following an EQ and prior to return to operation

The pier seismic isolation system must operate reliably over the 50-year observatory lifecycle

A pier re-centering and monitoring system (PRMS) is required to provide the ability to return the pier to its nominal operating position after a seismic event

Special Seismic Considerations

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The GMT enclosure must be robust for 50 years of operation

▪ Approximately 3600 earthquakes over the 50-year lifecycle

▪ Average of 6 earthquakes per month

▪ Large Chilean earthquakes can last for 3 minutes or longer (!)

The GMT enclosure design must also consider structural safety and integrity during the construction phase, which will experience ~200 earthquakes (!)

Conclusions

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The GMT project is exempt from Chilean permitting and approval processes

The GMT enclosure design shall be executed according to the Normas Chilenas at a minimum, and to additional (more restrictive) codes as noted.

The GMT pier seismic isolation system is unique, and its design must support science operations while protecting the telescope from frequent seismic events

The GMT enclosure must be robust against 50 years of seismic activity, including hundreds of earthquakes during the construction phase

GMTO Corporation |1310 December 2020 Special Considerations