blast performance of point fixed assemblies utilizing tssa · blast performance of point fixed...

dowcorning.com/constructionDow Corning Confidential - INTERNAL

Blast Performance of Point Fixed

Assemblies utilizing TSSAJon Kimberlain and Lawrence D. Carbary

Dow Corning Corporation

TSSA – Transparent Structural Silicone Adhesive

Transparent Structural Silicone Film Adhesive(TSSA)

• Simple application, preformed film,

easy to cut and apply, multiple

layers can be applied

• High transparency, crystal clear

• Strong adhesion performance

• Thermal stability

• UV resistance

• Excellent weatherability

• Removable

• High strength 190 psi dynamic

design stress

Chemistry and Cure Behavior

• One-part material (pre-

formed film)

• Heat-activated addition-

cure

• No cure by-products (and no odor) are

evolved during the reaction.

• Film adhesive is cured at temperatures of

275 °F for a period (soak time) of 30

minutes while applying pressure

• Optimum cure conditions are achieved in an

autoclave.

Challenges – Protective Glazing

Historical performance

• Previous Testing on Drilled Glass to Validate Performance of Fittings –

“Advances in Explosion Resistant Bolt Fixed Glazing” – GPD 2013 by Morgan

et. al..

• Strain Rate Behavior of Silicone Sealants – “Evaluation of Silicone Sealants at

High Movement Rates Relevant to Bomb Mitigating Window and Curtainwall

Design” – ASTM 2010 – Yarosh et. al.– Assume that TSSA has the same performance trends with conventional structural

silicones at high strain rated.

Stress–strain curve for conventional structural silicone0.00083 m/s vs. 1.0 m/s movement rate

Challenges – Protective Glazing

Design and Test Assembly with TSSA connections

• Target initial levels of protection according to AAMA 501-14, “Voluntary Guide

Specifications for Blast Hazard Mitigation for Fenestration Systems”– Loads of 6 to 10 psi with relevant impulse according to ASTM F1642, “Standard Test

Method for Glazing and Glazing Systems Subject to Airblast Loadings”

– The Risk Management Process for Federal Facilities: An Interagency Security

Committee Standard—dated August 2013

– The Unified Facilities Criteria (UFC) DoD Minimum Antiterrorism Standards for

Buildings (UFC 4-010-01 and UFC 4-010-02, 9 February 2012 with Change 1, 1

October 2013)

• Provide data that will enable design advancements for blast mitigation glazing

by having multiple tests demonstrating positive and negative performance.

9Dow Corning Confidential - INTERNAL

https://www.dhs.gov/publication/isc-risk-management-process

https://www.wbdg.org/ffc/dod/unified-facilities-criteria-ufc

Fabrication Process

Attach hardware to glass and place in frame.

Corner support 9mm Steel Plate with 18mm hole in each corner. 4 plates per frame.

7”

7”

11/16” hole

Center of 2.36”

diameter TSSA

attachment on

glass is 2” from

each edge in

corner

Glass Makeup and Fittings

Thickness – ¼” tempered

by 0.060” SentryGlas

by ¼” tempered

Applied in Autoclave

• 175 psi

• 270 °F

• 30 minutes of soak time

Each fitting was checked

at allowable stress

after application

• 40 ft-lbs torque

ASTM F1642

• 4 psi

40ft/(lbm TNT)1/3

0.33 lbm C4 50 ft

• 6 psi

27.5ft/(lbm TNT)1/3

0.88 lbm C4 76 ft

• 10 psi

18ft/(lbm TNT)1/3

1.6 lbm C4 76 ft

ASTM F2912

Shock Tube

Novel test facility located

underground at the

University of Kentucky

Use of actual explosives in the

test apparatus to simulate

both negative and positive

phase of blast event

Can accommodate rough

openings up 12’ by 12’

Instrumentation includes high

speed cameras, pressure

gauges and laser deflection

devices

Gravel mine

Pressure gauges

Frame 1 – Target 10 psi @ 89 psi-msGlass Fail

Frame #1

Test #1

Pressure

(psi)

Impulse

(psi-ms)

Deflection

(in.) AAMA 501-14 Ratings

1 9.289 75.824

ISC

Performance 5

2 10.070 84.527

ISC

Protection Low

3 10.723 78.527 ISC Hazard High

4 11.559 79.397

UFC

Protection

Below AT

Standards

AVE 10.410 79.355 -4 ASTM F 1642

High Hazard

(N/A)

Target 10 89 glass fail

Frame 1 - Results

Frame 2 – Target 4 psi @ 28 psi-msGlass Intact

Frame #2

Test #2

Pressure

(psi)

Impulse

(psi-ms)

Deflection


1 5.956 21.240

ISC

Performance 1

2 6.525 28.173 ISC Protection Safe

3 6.431 22.458 ISC Hazard None

4 6.764 22.174 UFC Protection High

AVE 6.419 23.511 -2/ + 1 ASTM F 1642

No

Break

(H1)

Target 4 28

glass

intact

Frame 2 – 6 psi @ 42 psi-msGlass Intact

Frame #2

Test #3

Pressure (psi)

Impulse(psi-ms)

Deflection (in.)

AAMA 501-14 Ratings

1 6.082 38.408ISC Performance

1



4 7.082 40.087UFC Protection

High

AVE 6.593 41.839 -2.2 / + 0.8 ASTM F 1642 No Break (H1)

Target 6 42 glass intact

Frame #2 – Target – 10 psi and 89 psi-msGlass Fail

Frame #2

Test #4

Pressure

(psi)

Impulse

(ps-ms)

Deflection


1 8.265 72.881

ISC

Performanc

e 5

2 8.530 74.882

ISC

Protection Low


4 9.948 74.201

UFC

Protection

Below

AT

Standard

s

AVE 9.032 75.732 -4 mm

ASTM F

1642

High

Hazard

(N/A)

Targe

t 10 89 glass fail

Frame 3 – Target 6 psi @ 42 psi-ms

Frame #3

Test #5

Pressure

(psi)

Impulse

(psi-ms)

Deflection


1 6.196 39.838

ISC

Performance 1




AVE 7.027 41.539 NO Data ASTM F 1642

No Break

(H1)

Target 6 42

glass

intact

Deflection data corrupted

and unavailable

Frame #3 – Target 10 psi @ 89 psi-ms Glass Fail

Frame #3

Test #6

Pressure

(psi)

Impulse

(psi-ms)

Deflection


1 8.265 79.063

ISC

Performance 5

2 8.692 78.275

ISC

Protection Low


4 10.625 79.391

UFC

Protection

Below AT

Standards

AVE 9.280 79.218 -7.5 ASTM F 1642

High Hazard

(N/A)


Frame #4 – Target 6 psi @ 42 psi-ms Glass intact

Frame #4

Test #7

Pressure

(psi)

Impulse

(psi-ms)

Deflection


1 6.381 39.1

ISC

Performance 1




AVE 6.879 39.346 -3 / + 1.5 ASTM F 1642

No Break

(H1)


Frame #4 – Target 10 psi @ 89psi-ms Glass Intact Surprise!

Frame #4

Test #8

Pressure

(psi) Impulse (psi-ms)

Deflection


1 8.481 79.567

ISC

Performance 1



4 11.116 82.147

UFC

Protection High

AVE 9.422 78.062 -4 / + 1.5 ASTM F 1642

No Break

(H1)


Frame #4 – Target 10 psi @ 89psi-ms Glass Fail

Frame #4

Test #9

Pressure

(psi)

Impulse

(psi-ms)

Deflection


1 8.708 80.219

ISC

Performance 5

2 9.066 76.767

ISC

Protection Low


4 10.520 80.265

UFC

Protection

Below AT

Standards

AVE 9.558 79.748 -7.5 ASTM F 1642 High Hazard (N/A)


High Speed Photos near Failure – Tests 4, 6 and 9

Conclusions

Based upon the standard, ASTM F2912-17, the standard window assembly tested

meets a hazard level of H1 at a specification level of C1.

• 2.36” diameter points 2” from each corner

• Architectural benefit, smaller spiders, less metal

• Standard construction

TSSA has been shown to be viable in providing protection and performance in

initial levels of bomb blast protection

• Test #8 suggests that the TSSA has increased stress and strain performance similar to

structural silicone

• Never has a load been placed on TSSA that equaled that test.

Glass breakage has been shown to be the weak link in the performance of the

system.

Existing data can be used to design higher performing systems

• Deflection data at low loads and high loads

• Thicker glass can be tested to validate TSSA actual strength

For further study, emphasis should be placed on appropriate sizing of glass

thickness to avoid breakage in fully adhered system.s

ThankYou

Dow Corning Confidential - INTERNAL

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blast performance of point fixed assemblies utilizing tssa · blast performance of point fixed...

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