ibc seismic code standards and installation requirements

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?


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Three variables determine a Seismic Design Category

Interpretation of installation practices by code officials and architects

Integration of seismic information into plans and specifications

This is a complicated issue !


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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.


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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


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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


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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Non-Structural Systems Get A Closer Look

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


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


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


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

IBC Category CISCA Zone Installation Requirement

C

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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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“Old” and “New” Code Comparison:

Seismic Design Categories D, E, and F


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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Alternative Designs and Methods

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

Armstrong has conducted 70 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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IBC Seismic Design Category D, E, F Alternative Installation Test:

The result: a more efficient installation – labor saving benefits.

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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BERC2 Cost Savings

Total savings with BERC2: 30%, or $ .116/LF.

The BERC2 eliminates the expense of stabilizer bars on the two unattached walls. The #7800 is substituted for the more expensive 2” molding.

This comparison is based on a Prelude 2’ x 2’ installation. Cost reflects April 1, 2004 pricing.

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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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BERC Cost Savings

Total savings with BERC Solution: $ .103/LF.

The BERC creates a tighter overall grid installation, more efficient squaring of grid, and

easier plenum access at the perimeter.

Savings calculation: BERC2 only placed at cut cross tees [3/4 of the perimeter] = $ .098 x ¾ = $ .074

This comparison is based on a Prelude 2’ x 2’ installation. Cost reflects April 1, 2004 pricing.

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BERC2 Cost Savings

IBC Requirements

Armstrong BERC2 Solution

Solution Benefits

2” molding 7/8” molding Narrow, sleek aesthetic with standard 7/8” wall molding

Attached grid on two adjacent walls [pop rivets are acceptable]

Attached grid on two adjacent walls with the BERC2. NOTE: Attaching the BERC2 clip to the wall secures the grid and eliminates the need for pop rivets through the visible part of the wall molding

Eliminates installation and aesthetic problems associates with 2” wall molding

¾” clearance at perimeter on unattached ends

BERC2 clip with ¾” clearance on unattached ends

BERC2 eliminates visible

pop rivets through the wall angle

Stabilizer bars to prevent the spread of main beams and cross tees

BERC2 clip on all four walls 1. Eliminates time and expense to install pop rivets

2. Eliminates stabilizer bars

3. Lower cost solution

4. Better access to the plenum

1. Heavy-duty grid

2. Lateral bracing

3. Perimeter support wire

1. Heavy-duty grid

2. Lateral bracing

3. Perimeter support wire

Meets code requirement

Two Approaches to IBC Categories D, E, F

New 2” BERC clip

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Additional Armstrong Testing

Performed extensive testing on standard, specialty and floating ceiling solutions

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

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

Shake Table Test - Infusions

Architects can specify and code officials approve non-standard ceilings confident that they have been tested to meet IBC requirements [Serpentina, Infusions, Axiom, WoodWorks and MetalWorks]!

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New Seismic Sales Aids

CS-3543 “Seismic Installations: What You Need to Know”

Key brochure messages:

1. Rationale for the development of the new IBC code

2. Reference to sections of the code that allow “alternative methods”

3. Side-by-side comparison between IBC requirements and BERC2 solution

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New Seismic Sales Aids

CS-3559 “Seismic Ceiling Installations”

Key brochure messages:

1. Don’t compromise your design intent [architect] with the use of 2” wall molding

2. Armstrong has demonstrated seismic performance with extensive testing on many systems

3. We provide specs, drawings, and continued education on the web

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

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Seismic National Advertising

You’ll see ads in industry periodicals such as Walls & Ceilings and AWCI’s Construction Dimensions this Spring.

Note reference to the web address specifically dedicated to Seismic information.

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What About Specifications?

Seismic Information in Construction Documents

Here’s what you need to look for:

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 might 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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Additional Resources and References

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

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

TechLine Can Provide Assistance!