espe sdnbc-course chapter-1-january_12-15, 2015

2014-10-11

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Seismic Design of Nonstructural Building Components January 12-15, 2015

Quito, Ecuador

Chapter 1

Introduction

Andre Filiatrault, Ph.D., Eng.


Quito, Ecuador

CONTENTS

1. Definition of Nonstructural Components

2. Classification of Nonstructural Components

3. Importance of Considering Nonstructural Components in Seismic Design

4. Challenges Associated with the Seismic Design of Nonstructural Components

5. Causes of Seismic Damage to Nonstructural Components

6. Performance of Nonstructural Components in Recent Earthquakes


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1. Definition of Nonstructural Components

• Every part of the building and all its contents with the exception of the structure.

• Everything except the columns, floors, beams, etc.

• Common nonstructural components include: ceilings; windows; office equipment; computers; inventory stored on shelves; file cabinets; heating, ventilating, and air conditioning (HVAC) equipment; electrical equipment; furnishings; lights; etc.

• Typically not analyzed by structural engineers and may be specified by architects, mechanical engineers (e.g. HVAC systems and plumbing for larger buildings), electrical engineers, or interior designers (contents).

• May be purchased without the involvement of any design professional by owners or tenants after construction of a building.

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• Nonstructural components can be

classified into three main categories:

– Architectural Components

– Building Utility Systems

– Building Contents


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• Architectural Components

– Built-in nonstructural components that form

part of the building.

– Examples: partitions and ceilings, windows,

doors, lighting, interior or exterior

ornamentation, exterior panels, veneer, and

parapets.


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Gypsum Wallboard Partitions Ceiling Systems

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Window Systems Doors


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Lighting Systems


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Interior Ornamentation Exterior Ornamentation

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Exterior Cladding Veneers


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Parapets


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• Building Utility Systems

– Built-in nonstructural components that form part of

the building.

– Examples: mechanical and electrical equipment and

distribution systems, water, gas, electric, and

sewerage piping and conduit, fire suppression

systems, elevators or escalators, HVAC systems, and

roof-mounted solar panels.

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Mechanical Equipment Electrical Equipment


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Piping Systems Pressurized Fire Sprinkler Systems


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Elevators Escalators

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HVAC Systems


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Roof-Mounted Solar Panels


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• Building Contents

– Nonstructural components belonging to tenants or occupants.

– Examples: computer and communications equipment; cabinets and shelving for record and supply storage; library stacks; kitchen and laundry facilities; furniture; movable partitions; lockers; and vending machines.

– Judgment needed to identify critical items in a particular building.

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Computer Equipment Communication Equipment


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Cabinets and Shelving


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Library Stacks Kitchen Furniture

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Movable Partitions Lockers


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Vending Machines


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Source: FEMA 74


Architectural ComponentsBuilding Utility SystemsBuilding Contents

Structural Components

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• Nonstructural components represent the major portion of

the total investment in typical buildings.

3. Importance of Considering Nonstructural

Components in Seismic Design

Fig 1. Investments in building construction (Miranda 2003)


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Components in Seismic Design• Nonstructural damage can limit severely the functionality

of critical facilities, such as hospitals.

Emergency Room of Veteran Hospital a few minutes after the 1994 Northridge Earthquake in California

Video


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Components in Seismic Design• Harmonization of seismic performance between

structural and nonstructural components becomes vital during an earthquake.

– Even if the good performance of structural components of a building allow its continuous and immediate occupancy after a seismic event, failure of architectural, mechanical or electrical components and contents can lower the performance level and functionality of the entire building system.

• Failure of nonstructural components can become a safety hazard or can hamper the safe movement of occupants evacuating or of rescuers entering buildings.

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Components in Seismic Design

• Damage to nonstructural components occurs at seismic

intensities much lower than those required to produce

structural damage.

– Steel moment-resisting frames yield at story drifts beyond 1%

while gypsum partition walls show significant crack at drifts as

low as 0.25%.

– In many past earthquakes, losses from damage to nonstructural

building components have exceeded losses from structural

damage.


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Components in Seismic Design• Risk Levels Associated with Damage to Nonstructural

Components

– Life Safety (LS) Could anyone be hurt by this component in an

earthquake?

– Property Loss (PL) Could a large property loss result?

– Functional Loss (FL) Could the loss of this component cause an

outage or interruption?


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4. Challenges Associated with the Seismic Design of

Nonstructural Components• In comparison to structural components and systems, there is

much less information available giving specific guidance on the seismic design of nonstructural building components for multiple-performance levels.

• Limited basic research has been done and often design engineers are forced to start almost from square one: observe what goes wrong and try to prevent repetitions.

– Consequence of the empirical nature of current seismic regulations and guidelines for nonstructural components.

– Design information currently available for the most part is based on judgment and intuition rather than on experimental and analytical results.

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4. Challenges Associated with the Seismic Design of

Nonstructural Components• Multiple factors affecting the

seismic behaviour of nonstructural components.– the regional seismicity

– the proximity to an active fault

– the local soil conditions

– the dynamic characteristics of the building structure

– the dynamic characteristics of the nonstructural element and its bracing to the structure

– the location of the nonstructural component within the building

– the function of the facility

– the importance of the particular component to the operation of the facility

Factors influencing structural response

Supplemental factors influencing nonstructural response


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5. Causes of Seismic Damage to

Nonstructural Components• Earthquake ground shaking has three primary

effects on nonstructural elements in buildings:

– Inertial Effects

– Distortions imposed on nonstructural components

when the building structure sways back and forth

– Separation or pounding at the interface between

adjacent structures

– Nonstructural interaction


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Nonstructural Components• Inertial Effects

– Inertia forces caused by accelerations at various

level in the structures.

– Cause overturning or sliding in mainly

“acceleration-sensitive” nonstructural components.

• e.g. unrestrained file cabinets, emergency power

generating equipment, freestanding bookshelves, office

equipment, and items stored on shelves or racks

Source: FEMA 74

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Nonstructural Components• Inertial Effects

Video


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Nonstructural Components• Building Distortion

– Seismic response of a building gives rise to inter-

story displacements or drifts.

– Cause distortions in “drift-sensitive” nonstructural

components.

• Windows, partitions, and other items that are tightly

locked into the structure.

Source: FEMA 74


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Nonstructural Components• Building Separation

– Pounding of closely spaced adjacent buildings may

occur during earthquakes.

– Cause damage to acceleration-sensitive and drift-

sensitive nonstructural components crossing the

separation.

• Parapets, veneer, or cornices on the facades, flashing,

piping, fire sprinkler lines, HVAC ducts, partitions, and

flooring.

Source: FEMA 74

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Nonstructural Components• Nonstructural Interaction

– Interaction between nonstructural components may share the same space in a ceiling plenum or pipe chase.

– These items may have different shapes, sizes, and dynamic characteristics, as well as different bracing requirements vibrate differently from one another causing dynamic interaction.

– Examples:• Sprinkler distribution lines interacting with the ceiling causing the

sprinkler heads to break and leak water into the room below.

• Adjacent pipes of differing shapes or sizes are unbraced and collide with one another or adjacent objects.

• Suspended mechanical equipment swings and impacts a window, louver, or partition.

• Ceiling components or equipment can fall, slide, or overturn blocking emergency exits.


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6. Performance of Nonstructural

Components in Recent Earthquakes• Five Case Studies

– 2001 Nisqually US Earthquake

– 2010 Maule Chile Earthquake

– 2010 & 2011 Christchurch New Zealand Earthquakes

– 2011 Tohoku Japan Earthquake

– 2011 Virginia US Earthquake


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Components in Recent Earthquakes• 2001 Nisqually US Earthquake

– Mw = 6.8

– Struck the Puget Sound in the western region of Washington State on February 28, 2001 at 10:54 am (PST) and originated at a depth of 52 km

– Because of focal depth of 52 km, only light-to-moderate ground shaking

– Large portion of the estimated two billion dollar loss associated with damage to nonstructural components,

– Seismic event particularly interesting for studying the seismic performance of nonstructural components.

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Components in Recent Earthquakes• 2001 Nisqually Earthquake in the United States

– ShakeMap


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– Performance of Architectural Components

• Suspended Ceiling Systems

– One of the most common types of nonstructural component

failure related to suspended ceiling systems.

Generalized failure of suspended ceiling light fixtures in an office building in downtown Seattle. Although the eccentrically braced steel frames used to seismically upgrade the building performed as intended, the suspended lighting fixtures were unable to accommodate the induced lateral acceleration and caused significant damage to the offices, Fortunately, only minor injuries resulted from the failure of suspended lighting fixtures throughout the building.


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• Interior Partition Walls

– Cracking observed in many buildings.

– Diagonal and vertical cracking occurred at upper corners of

doors and window openings and at the intersection of beams

and walls.

– Heavy masonry partition walls, particularly in stairwells,

suffered severe cracking as a result of building drift.

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• Interior Partition Walls


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Components in Recent Earthquakes

• 2001 Nisqually Earthquake in the United States


• Window Systems

– Shattering of glass windows occurred at several locations.

– Control tower at Sea-Tac airport loss of all but one window.

» Main contributor to the shutdown of the airport for hours

following the earthquake.

» Air-traffic control had to be relocated into a temporary

trailer.

» Prime example of how damage to nonstructural

components can limit severely the functionality of critical

facilities.


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• Window Systems

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• Unreinforced Masonry Parapets

– Total or partial collapse of parapets was the most common type

of damage suffered by buildings.

Military dormitory building in Fort Lewis Building in Downtown Seattle


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• Chimneys

– Unbraced chimney failures were observed mostly in residential

buildings.

– Braced chimneys performed well.


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• Chimneys

Three-story light-frame wood house in Olympia

Undamaged braced chimney of a wood army barrack in Fort Lewis

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• Performance of Building Utility Systems

– Several water and gas lines of mechanical equipment inside

buildings were severed during the ground shaking.

A 75 mm diameter water pipe broke in the mechanical room on the roof of a hotel building in Olympia, causing 3000 litres of water in a storage tank to flood several floors of the building. The unsecured water tank was shifted about 150 mm along the floor. This, in turn, caused the supply water line to the tank to rupture. As a result of the failure of this mechanical equipment, the hotel had to be evacuated and shut down after the earthquake.


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– Performance of Building Contents

Failure of bookshelves that caused books to fall in a library in Olympia. The detail of the screwed wood-to-metal connection that failed at the top of one of the leaning bookshelves is also shown.


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– Performance of Building Contents

Overturning and damage to furniture in guest rooms on the top floor of an eight-story hotel building in Olympia. In the bottom five floors most of the furniture remained in the upright position. None of the guest room furniture in the building had been fastened to the walls to prevent overturning.

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Components in Recent Earthquakes• 2010 Maule, Chile Earthquake

– Contributors:

• Dr. Eduardo Miranda, Stanford University, CA

• Dr. Gilberto Mosqueda, University of California, San Diego

• Dr. Gokhan Pekcan, University of Nevada, Reno, NV

• Dr. Rodrigo Retamales, Consulting Engineer, Santiago, Chile


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– Magnitude 8.8

– Struck on February 27, 2010 at 3:35 am local time.

– Felt by approximately 80% of the population.

– 525 death

– Approx. 200,000 housing units affected .

– Approx. 800,000 homeless.

– Economic loss approx. US $25 billion.


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– Chile is a country with a long history of large

earthquakes.

– Long tradition in Earthquake Engineering (e.g.

4WCEE 1969).

– Very good and well enforced building codes.

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– Affected Area and ShakeMap


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– Impact of nonstructural damage on airports

• Closure of the Santiago and Concepcion International

Airports.

• US$40 million for repairs of nonstructural damage at SCL.

• US$10 million loss to Lan Chile.

• Two thirds of the Chilean air traffic interrupted.


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• Failure of suspended air handling units and ceiling tiles

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• Failure of suspended air handling units and ceiling tiles


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• Failure of sprinkler piping bracing


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• Failure of sprinkler piping bracing

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• Failure of sprinkler piping hangers


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• Failure of sprinkler piping joints


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• Failure of sprinkler piping tee joints

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– Impact of nonstructural damage on hospitals

• 130 hospitals were affected in six regions,

– represents 71% of all public hospitals in the country,

– 4 were completely shut down,

– 12 loss more than 75% of their capacity,

– 8 partially loss their functionality,

• 62% of hospitals required repairs or replacement,

• 18% of the hospital beds in public hospitals were lost for at least one month,

• The ministry of health estimated it will require US$ 2.8 billion to repair hospital damage,


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• Felix Bulne Hospital in Santiago shut down primarily due

to nonstructural damage.


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• Damage to wall-mounted monitors at Talcahuano and

San Carlos Hospitals.

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• Damage to wall-mounted monitors in Hospitals.

– Seismic Testing at the University at Buffalo


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• Damage to HVAC Equipment.


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• Damage to HVAC Equipment

– Roof-mounted small AC units at the Clínica del Maule in Talca

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• Damage to Elevators


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• Damage to medical gas lines


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• Damage to ceiling systems

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• Damage to ceiling systems


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– Impact of nonstructural damage on industryCompany Industry

Estimated Loss

(USD millions) Type of Loss

Grupo Arauco Pulp, Plywwod Producer and Saw Mill. 400 to 600Approximately 65% of the loss is

from business interruption

Grupo Quinienco Brewery, Winery and Manufacturing 300 60% from business interruption

CMPC Pulp and Paper Manufacturer 170 60% from business interruption

D&S (WalMart Chile) Retail Stores 150 Primarily physical damage

ENAP Oil and Gas 150Evenly distributed between physical

damage and business interruption

CAP Steel Mill (Huachipato Plant) 140 60% from business interruption

Viña Concha y Toro Winery 110Evenly distributed between physical


Telefónica Communications 100 Primarily physical damage

Grupo Claro Winery, Communications, TV channel, Bottler 84Evenly distributed between physical


Censosud Retail 72 Primarily physical damage

Carozzi Food Manufacturer 60 Primarily physical damage

SCL - Santiago Airport Infrastructure 40 Primarily physical damage

Fallabella Retail - Largest chain of retail stores in Chile 42 Primarily physical damage


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– Impact of nonstructural damage on industry

• Ceiling-sprinkler head dynamic interaction

Note:1 in. = 25.4 mm

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• Damage to elevators


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• Damage to water pipes


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• Damage to glazing

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• Damage to storage racks

– Considered as non-building structures in the US.

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• Damage to storage racks

– Considered as non-building structures in the US.


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– Examples of good performance


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– Examples of good performance

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– Final comments

• In general very good structural performance of building relative to the magnitude of the event (8.8).

• Massive amount of nonstructural damage that lead to large impact and significant disruption to Chilean society.

• Very large economical losses (approx. US$25 billion) which represents 12% of country’s GDP.

• There were many examples in which details, similar to those used in the U.S., were not enough to prevent significant damage and impact.


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Components in Recent Earthquakes• 2010 and 2011 Christchurch New Zealand

Earthquakes

– Contributors:


• Dr. Kenneth Elwood, University of British Columbia, BC


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Earthquakes

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Earthquakes


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Earthquakes

– A country with a long history of moderate and large

earthquakes.

– Long tradition in Earthquake Engineering (e.g.

3WCEE, 1965; 12WCEE, 2000).

– Very good and enforced building codes.


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Earthquakes

– Three main types of damage observed in these

earthquakes:

• Damage/collapse to URM structures.

• Massive liquefaction and associated damage.

• Large amount of nonstructural damage.

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Earthquakes

– Damage to building contents


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Earthquakes



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Earthquakes


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Earthquakes

– Damage to ceilings


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Earthquakes

– Damage to facades


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Earthquakes

– Damage to glazing

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Earthquakes

– Damage to stairs and elevators


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Earthquakes

– Damage to storage racks


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Earthquakes

– Final Comments

• Relatively small number of collapses/fatalities.

• Good structural behavior of new engineered construction.

• Extremely large economical losses (approx. US$17 billion)

considering the magnitude of the events (7.1 and 6.3) and

especially relative to the population of Christchurch (385,000).

• Nonstructural damage is costly and affects business recovery.

• Long-lasting effect for the economy of Christchurch specially

for the downtown commercial district.

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Components in Recent Earthquakes• 2011 Tohoku Japan Earthquake

– Contributors:

• Dr. Gilberto Mosqueda, University of California, San

Diego


• Dr. Dimitrios Lignos, McGill University, Montreal, Canada


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– Magnitude (Mw): 9.0

– Depth: 32 km

– Distance from Shore: 70 km

– Rupture zone: 500 x 200 km

– PGA: 2.9g measured

– Tsunami: >35 m

– Casualties: ~ 25,000

– Refugees: 151,000

– Economic Loss: > US$309 B

– Cost of Recovery: > US$615 B


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– Large investment in earthquake preparedness –

tsunami warning system and adoption of advanced

technologies

– Strong research program in earthquake engineering

(US-Japan cooperative research program in many

areas)

– Advanced and enforced seismic codes

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– Non-Structural Damage - Sendai


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– Damage to precast ACC (Autoclave Lightweight

Aerated Concrete - ALC) façade elements

Angle used for alignment

9-mm Re-bar

Mortar

9-mm Re-bar

Mortar

Weight supporting angle

Typical Failure modes observed also in past earthquakes: (1) cracking andchipping of ALC, (2) debonding between rebar and mortar, (3) fracture ofrebars, ALC fallingFor newer Japanese residences virtually no damage in their ALC panels� The sliding or rotating panel method was adopted for those � Reinforcingbars are disconnected at the individual stories

(Summary prepared by Dr. Taichiro Okazaki, Dr. Dimitrios Lignos and Dr. Mitsumasa Midorikawa)

ALC panels are rigidly connected to structural frame

Minimum specified compressive strength of 3.0MPa

Min Thickness of 100mm

Typically used in 600mm modules


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– Non-Structural Damage - Tokyo


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– Ceiling Damage - Tokyo


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– Final Remarks

• Not considering tsunami inundation zone, there was very

little structural damage considering intensity of shaking.

• Majority of damage in large cities including Tokyo and

Sendai was mainly nonstructural.

• Frequently observed non-structural damage:

– Ceiling damage / collapse.

– Damage / collapse older ACC façade panels.

– Overturning/sliding of contents.

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Components in Recent Earthquakes• 2011 Virginia US Earthquake

– Contributors:

• Dr. Gilberto Mosqueda, University of California, San

Diego



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– Final Remarks

• Damage to suspended ceilings, masonry chimneys, masonry veneer, masonry infills was widespread.

• Damage to contents in residential and commercial buildings.

• Reports of pipe burst in Pentagon causing minor flooding.

• Damage resulted in closure and reduced functionality of some buildings including schools.


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Components in Recent Earthquakes• Lessons from Recent Earthquakes

– Recent earthquakes described occurred in countries

with a long strong tradition in Earthquake Engineering.

– Structural damage in these earthquakes was relatively

small in structures designed according to recent codes.

– Large amounts of nonstructural damage occurred that

lead to significant impacts on facilities and society in

general.

– Nonstructural damage often occurs as a result of

problems in the bracing and anchorage.

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Components in Recent Earthquakes• Lessons from Recent Earthquakes (cont’d)

– In many cases the failure is due to the deformation, vibration, and pounding of neighboring components. In current practice the deformation of the components is typically not addressed.

– These earthquakes highlight the need of performance based design for controlling economic losses and downtime in addition to life safety through enhanced seismic design of nonstructural systems.


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Questions/Discussions

espe sdnbc-course chapter-1-january_12-15, 2015

Engineering

nonstructural components6

design professional

seismic damage

seismic design4

hvac systems

electrical engineers

utility systems

exterior panels