IBC Seismic Code Standards and Installation Requirements

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What Is The IBC?

It is the first model building code to specifically address the differences in seismic hazard based on soil type.

It can significantly impact the cost of installing suspended ceilings in areas that have not historically required seismic installations

Today’s Seismic Standards

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Currently 45 states use the International Building Code

66% of the U.S. is now at some level of risk

25 – 40% chance for a major quake in the Midwest

How Big Is The Risk?

                                      

Today’s Seismic Standards

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Three variables determine a Seismic Design Category

Interpretation of installation practices by contractors and code officials

Integration of seismic information into plans and specifications

This is a complicated issue !

Today’s Seismic Standards

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According to the International Building Code [IBC], a Seismic Design CategorySeismic Design Category must be established for each construction projecteach construction project based on three variablesthree variables:

anticipated ground motion

type of soil in a specific geographic area

seismic [building] use group designation

In the former CISCA zone classification, an entire geographical area determined construction methods. The IBC ‘project by project’ analysis is a major change!

The design team is responsible for the analysis required to assign a Seismic Design Category to a project.

Today’s Seismic Standards

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Seismic Design Category – Variable 1

Determine Maximum Ground Motion

Ground acceleration is evaluated by location on hazards maps

Two maps are used to list ground motion at 0.2 and 1 second periods

Ground motion is presented as a percentage of the acceleration of gravity

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Soil type is evaluated to a depth of 100'

The “Site Class” is rated A through F, where A is hard rock and F is more unstable soil types

Site Class D is used when specific data is not available unless class E or F soil types are likely

Determine [Soil] Site Class

Seismic Design Category – Variable 2

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Seismic Use Group I – normal occupancy Examples: everything not assigned to another group

Seismic Use Group II – high occupancy Examples: schools, large office buildings and utilities

Seismic Use Group III – essential use Examples: police and fire stations; medical facilities

Determine Seismic Use Group

Seismic Design Category – Variable 3

A risk factor is assigned based on the occupancy of the structure and how critical the operability of the facility is in the event of a disaster, such as an earthquake.

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What About Specifications?

Seismic Information in Construction Documents

This may vary by location, but:

1. A Seismic Design Category [SDC] tells the construction team what level of performance the building and its systems must achieve

2. SDC is to be listed in the construction documents

3. While exact location in the CDs may vary by jurisdiction, most likely it will be in the general conditions section of the specification, and in general notes on the first page of structural drawings

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Non-Structural Systems Get A Closer Look

Before IBC: Suspended ceilings could fail and render a space unusable

Today’s Seismic Standards

After IBC: Suspended ceilings – designed and installed to meet IBC Seismic Design Categories – can survive intact

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IBC Installation Requirements for Suspended Ceilings

Provide a suspension system strong enough to resist lateral forces imposed upon it without failing

Prevent border panels from falling from the ceiling plane

Today’s Seismic Standards

Perimeter Wires – Categories D, E, and F

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“Old” and “New” Code Comparison:

Seismic Design Category A and B

Seismic Code Compliance

The IBC does not require any special ceilinginstallation considerations in these categories

IBC Category CISCA Zone Installation Requirement

A, B 0-1 Ceiling installations should conform to basic minimums established in ASTM C 636.

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“Old” and “New” Code Comparison:Seismic Design Category C

Seismic Code Compliance

The objective of this standard is to create an unrestrained ceiling.

IBC Category CISCA Zone Installation Requirement

C

2

To be installed to CISCA recommendations for areas subject to light-to-moderate seismic activity:

Minimum 7/8” wall molding Grid must not be attached to the wall molding 3/8” clearance on all sides 3/8” overlap of the grid on the wall molding Ends of main beams and cross tees must be tied

together to prevent their spreading No perimeter wires

The IBC installation requirements for Seismic Design Category [SDC] C exempts ceilings in most one and two story buildings unless they are Seismic Use Group III [essential facilities].

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Seismic Code Compliance

The “unrestrained ceiling”Seismic Design Category C

The notion of a free-floating ceiling is new, and will impact the installed cost

Ceilings that cannot touch the walls are more expensive to install, because it is harder to keep them straight and square

Estimated cost increase per SF is 10-15%

Seismic Installation – Braced Perimeter Soffit

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“Old” and “New” Code Comparison:

Seismic Design Categories D, E, and F

Seismic Code Compliance

This practice creates a restrained ceiling.

IBC Category

CISCA Zone Installation Requirement

D, E, F 3-4

To be installed to CISCA recommendations for areas subject to severe seismic activity. IBC categories D, E, and F must also meet these additional requirements:

Minimum 2” wall molding Grid must be attached to two adjacent walls – opposite walls must have a

¾” clearance Ends of main beams and cross tees must be tied together to prevent their

spreading Perimeter support wires Heavy-duty grid system Ceiling areas over 1,000 SF must have horizontal restraint wire or rigid

bracing Ceiling areas over 2,500 SF must have seismic separation joints or full

height partitions Ceilings without rigid bracing must have 2” oversized trim rings for sprinklers

and other partitions Changes in ceiling plane must have positive bracing Cable trays and electrical conduits must be independently supported and

braced Suspended ceilings will be subject to special inspection

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Seismic Code Compliance

Seismic Design Categories D, E, and F

Meeting the most rigorous code guidelines costs 50% more than Seismic Design Category A or B [standard suspended ceiling installation practices]

The cost increase is associated with the labor and materials to install the suspension system and perimeter components

Note the use of 2” wall molding in this photo.

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Alternative Designs and Methods

Code officials may approve other installation designs based upon the following:

Armstrong has conducted full scale seismic tests.

IBC Section 104.11 Alternative materials, design and methods of construction and equipment. The provisions are not intended to prevent the installation of any material … providing that alternatives are approved.

IBC Section 101.11.1 Tests. Whenever code compliance is questionable … the building official can require tests as evidence of compliance.

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Alternative Designs and Methods

IBC Seismic Design Category C Alternative Installation Test:

The result: a ceiling that is easier to square at the perimeter.

Tested Prelude XL intermediate-duty main beams [7300] and cross tees [XL7342 and XL7328] and 7/8” wall molding. The system was installed according to the IBC Category C with the following exceptions:

1. Used BERC clip to eliminate stabilizer bars

2. Installed grid tight to two adjacent walls - and less than ¼” clearance on the opposite walls

Verified that the system meets required code performance.

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Alternative Designs and Methods

Another Approach to Seismic Design Category C

One of our suspension system accessories, the BERC clip, offers an alternate method to prevent grid from spreading

The BERC costs less than stabilizer bars and does not interfere as much with placement and removal of border panels

Arrow indicates stabilizer bar at perimeter

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Alternative Designs and Methods

IBC Seismic Design Category D, E, F Alternative Installation Test:

Special note: only heavy-duty grid options are acceptable.

Tested Prelude XL with heavy-duty main beams [7301] and cross tees [XL7348 and XL7328]. The system was installed according to CISCA guidelines for seismic restraint, and the IBC, with the following exceptions:

1. Used 7/8” wall molding [7800] instead of 2” wall molding

2. Used 2” BERC clips [BERC2] and eliminated the need for stabilizer bars

This test verified that the system meets code performance requirements.

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Heavy-Duty Grid Options

Design Options are Limited in Seismic Design Category D, E, F

Suspension Systems – General Applications

1. Prelude 15/16” t-bar

2. Suprafine 9/16” t-bar

3. Silhouette 9/16” t-bar

Suspension Systems – Special Applications

1. Clean Room 1-1/2” t-bar

2. Prelude Plus 15/16” t-bar

                                                                      

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Additional Armstrong Testing

Over 70 tests performed!

Code officials must approve all drawings of public buildings before bidding

Liability can be a major issue if products vary from the IBC code

Specialty ceilings, like wood or metal, can be a concern for code officials. Armstrong can provide test results for products you may want to specify for signature spaces.

                                                             

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Additional Armstrong Testing

Armstrong has performed extensive testing on standard, specialty, and floating ceiling solutions

Testing was performed at the State University of New York at Buffalo – Armstrong is a premier Multidisciplinary Center for Earthquake Engineering Research [MCEER] partner

We’ve also tested “specialty” and “floating” systems!

Shake Table Test - Infusions

You can specify non-standard ceilings confident that they have been tested to meet IBC requirements [Serpentina, Infusions, Axiom, WoodWorks, and Metalworks]!

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Other Seismic Support Tools

Latest product and solution news

Seismic Test Summaries

Seismic Design Solution CAD renderings

Seismic FAQs

IBC Guide Specification

For Seismic Information on the Web: www.armstrong.com/seismic

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Other Seismic Web sites

For More Seismic Information on the Web Visit These Code Related sites

                                                               

                         

Name of the Organization Web site

American Society for Testing and Materials [ASTM] www.astm.org

Building Seismic Safety Council [BSSC] www.nibs.org

Federal Emergency Management Agency [FEMA] www.fema.gov

International Code Council [ICC] www.iccsafe.org

United States Geological Survey [USGS] geohazards.cr.usgs.gov

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Additional Resources and References

1. The 2004 Armstrong catalog references Seismic performance [note the new icons].

2. Need guide specs, samples, or additional technical assistance? We can help you meet Seismic code requirements on your projects. Call TechLine for all your Seismic needs.

3. Need AIA CES credits? We can deliver an AIA approved program worth one learning unit [LU]. This course meets health, life safety, and welfare guidelines!