glass aluminum stainless steel 2011

8/17/2019 Glass Aluminum Stainless Steel 2011

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Designing with Glass

Aluminum andStainless Steel

Presented by: Tom Castle, S.E.

Ficcadenti Waggoner & Castle

Walnut Creek, CA

SEAONC 12/14/11


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Designing with Glass Aluminum

and Stainless Steel

Presentation is an overview of the subject withconcentration on the building industry

Many designs are done by manufacturers or on adesign-build basis with specialty engineers

Having a basic knowledge is important to know

what is possible and how the specifications for thedesign should be completed


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2009 IBC or 2010 CBC

Chapter 14 – Exterior Walls

1403.3 – Design walls to resist load per Chapter 16

1405 – Wall Coverings including glass, stone and masonry

veneer requirementsChapter 16- Structural Design

1604.3 – Serviceability limits for wall deflections

Deflections based upon 70% of Component and Cladding Loads

L/175 for Aluminum mullions supporting glass edges for each

light or L/60 total1607.7.1 Handrails and Guardrail loading

Chapter 24 – Glass and Glazing

2407 – Glass in Handrails and Guards

ASTM C 1036 – Standard Specification for Flat Glass

Glass –Building Code


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Glass

How does glass behave?

•Glass has shown an almost perfect elastic, isotropic behavior andexhibits brittle fracture.

•It does not yield plastically, which is why local stress concentrations arenot redistributed like most building materials.

•The tensile strength of glass is dependant upon mechanical flaws at thesurface.

•Glass fails when the tensile stress at the tip of one flaw reaches acritical value.

•Compressive strength is irrelevant for almost all structural applications


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GlassGlass Processing

Annealed Glass:This is standard float glass. This is weakest and typically

breaks into large fragments.

Tempered glass (heat treatment):This process creates a favorable residual stress field with

tension on the interior and compression on the surface. This type hasthe highest structural capacity. Residual strength is lowest and breaks

into small fragments.

Heat Strengthened Glass:This is between the two above. It has residual compression

stresses at a lower level them fully tempered, but produces largerfragments upon failure allowing for some post failure capacity.


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Glass


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Glass


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Glass

Heat Soaking:

There is a small risk of spontaneous failure in tempered glass within afew years of production. This is caused by nickel sulfide inclusions inthe glass. Heat soaking process is used to reduce the risk of this failurein the field by causing the failure in the soaking process thus eliminatingthe flawed pieces.


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Glass

Laminated Glass:

•This is two or more panes bonded togetherby some transparent plastic interlayer.

•This process allows for significantimprovement in post breakage behavior.

•Most common interlayer is polyvinyl butyral(PVB)

•The larger the fragmentation of the glassthe larger the post breakage capacity.


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Glass

Design Methods:

•For common geometries and loadingconditions hand calculations based upontables and graphs are usually sufficient for

determining stresses and deflections

•Finite element analysis is typicallyconducted for more complex geometry

•Meshes are denser at discontinuities orbolt holes•Fixing points must be accuratelymodeled in terms of rotational stiffness•Contact with metal is avoided andachieved by using liner, gasket orbushing. Models should only allow forcompression at contact surfaces


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Glass

Design Methods:

•For common geometries and loadingconditions hand calculations based upontables and graphs are usually sufficient for

determining stresses and deflections

ASTM E1300 has tables and graphs:


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GlassDesign Methods: ASTM E1300 has values for allowable stresses in types of glass for 3 secondduration loads based upon probabilities of breakage.Probability of 8 lites per 1000 is typically used for vertical glazing.Probabilities down to 1 lite per 1000 can be used in critical applications or

overhead applications.


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GlassDesign Methods:Glass strength is time dependant. ASTM E1300 gives Load Duration Factors


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GlassDesign Methods:

Structural Silicone Sealants


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GlassDesign Methods:

Structural Silicone Sealants – Values can be tested or 20 psi as a rule of thumb


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GlassDesign Methods:Point Supported Glass: General rule of thumb is bearing load of 4,000 lbs/per inch ofglass thickness actual design values may be based upon FEM or testing.


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Glass

Design Methods:


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Chapter 20 – Aluminum

Refers to Aluminum Design Manual for Design and Chapter 16for Loads

Aluminum –Building Code


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Aluminum

ADM utilized either ASD or LRFD design methods.


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Aluminum

Aluminum is typically alloyed with other metals toachieve desired properties. Each alloy is

designated by a four digit series.


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Aluminum


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Aluminum

6061 Aluminum is a common type used in

building industry. It has a yield stress of 36 KSI


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Aluminum

ADM has industry standard shape properties


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Aluminum

ADM has formulas for different shapes andloadings to determine allowable stresses.


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Aluminum

Welding significantly reduces the permittedstresses in the material.


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Chapter 22- Steel

2210 – Cold Formed Steel refer to AISI Design Manuals

ASCE8-02 for Cold Formed Stainless Steel – Not referenced

Where is Stainless in the code?

Stainless –Building Code


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Stainless

Stainless is not like Structural Steel• Anisotropy – Not the same properties in longitudinal and

transverse not tension and compression•Nonlinear stress strain – Gradual Yielding•Low proportional limits – Affect buckling behavior•Pronounced response to cold working


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Stainless

Cold Formed Stainless Steel can be designed using ASCE 8-02


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Stainless•No American Building Code Manual (otherthan cold formed – ASCE 8)

•Not referenced in IBC

•Use engineering judgment and AISC as abasis knowing its limitations

•Some European Codes are available formore complex analysis

•Usually used in simple applications andconservative analysis is sufficient


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Stainless

Types of Stainless Steel TypicallyUsed:

There are many types of stainless with variedproperties.

Most typically ASTM 304 or 316 are used inbuilding construction. 316 is more corrosionresistant than 304 and typically is also moreexpensive. Both have typical yield stresses in therange of 42 KSI.

The steels of type ASTM 304, 316, 304L, and 316Lhave very good weldability.


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Designing with Glass Aluminumand Stainless Steel

Corrosion Issues:


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Corrosion Issues:

Fasteners in Aluminum should be Cadmium, Zinc,Chromium or Tin plated. Stainless fasteners arealso acceptable.

Aluminum will corrode if embedded or touchingconcrete with calcium chloride. If the aluminum is

coated and chlorides are not present then nocorrosion.

Mild steel fasteners should not be used to connectstainless members.


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Seismic Issues (drift accommodation):

ASCE13.5.3: Exterior Nonstructural WallElements and Connections

ASCE 13.5.9: Glass in Glazed Curtain Walls,Glazed Storefronts and Glazed Partitions


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Seismic Issues: ASCE 13.5.3

Dp

Interstory

Total

Joint atHead ofWindow

FloorBeyond


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Seismic Issues: ASCE 13.5.3Dfallout >= 1.25 I Dp

Exceptions:

Glass with Sufficient Clearance to its frame such thatphysical contact between the glass and frame will notoccur at 1.25 Dp

Fully tempered monolithic glass no more than 10 feetabove a walking surface

Annealed or heat treated laminated glass that iscaptured mechanically by a wall system glazing pocket

Dfallout is determined in accordance with AAMA 501.6 or byengineering analysis


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Seismic Issues: ASCE 13.5.9

glass aluminum stainless steel 2011

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