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VSEC Seminar March 26, 27 2008 Virginia Beach, VA Richmond, VA David DeSutter, P.E. Director of Engineering and Customer Service EFCO Corporation Mitch Snead The Snead Company. VSEC Seminar March 26, 27 2008 Virginia Beach, VA Richmond, VA
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VSEC Seminar March 26, 27 2008 Virginia Beach, VA Richmond, VA David DeSutter, P.E. Director of Engineering and Customer Service EFCO Corporation Mitch Snead The Snead Company
VSEC Seminar March 26, 27 2008 Virginia Beach, VA Richmond, VA Better Communication = Better Overall Structure Pondering Point: During a “design event,” the typical commercial “window” will fail due to either improper anchorage or under-designed surrounding conditions.
VSEC Seminar • March 26, 27 2008 • Curtain Wall vs. Storefront (General, Construction, Connection and Anchors) • Curtain Wall Performance – Wind, Snow, Seismic, Thermal, Impact, Blast • CW/SF Manufacturer’s Design Considerations (What We Need) • CW/SF Manufacturer’s Design Considerations (What We Get) • CW/SF Manufacturer’s Design Considerations (What We Assume) • CW Analysis, Rules of Thumb • Reference Information
Curtain Wall vs. Storefront - General Storefront • Available in three basic variations (“plane of glass”): • outside set, • center set (a.k.a..flush glaze), • and inside set. OUTSIDE SET (S945) CENTER SET (S403) INSIDE SET (S433)
Curtain Wall vs. Storefront - General Storefront Most Storefront is available in three (3) configurations (“glazing method”): Outside glazed Inside glazed Vertical SSG glazed
Curtain Wall vs. Storefront - General Storefront Most Storefront is available in two (2) types of connections (“installation method”):
Curtain Wall vs. Storefront - General Storefront • Most Storefront is available in limited widths • and depths: • 2” – 3” in width • 4” – 6 ½” in depth
Curtain Wall vs. Storefront - General Curtain Wall • Primarily available in one basic variation (“plane of glass”):
Curtain Wall vs. Storefront - General Curtain Wall • Primarily available in three (3) basic configurations (“glazing method”): Outside glazed Inside glazed Structurally glazed
Curtain Wall vs. Storefront - General Curtain Wall • Primarily available in two (3) basic connections (“installation method”): Shear Block Screw Spline “Unitized”
Curtain Wall vs. Storefront - General Curtain Wall • Options, Options, Options
Curtain Wall vs. Storefront - General Water Performance
Curtain Wall vs. Storefront - General Water Performance – Curtain Wall
Curtain Wall vs. Storefront - General Water Performance – Storefront
Curtain Wall vs. Storefront - General Water Performance – Storefront
Anchor Bolts Control! Movement Allowances Unlimited (?) Rwl Curtain Wall vs. Storefront - General Curtain Wall Anchors – Head & Sill Direct Load Path to MWFRS
Curtain Wall vs. Storefront - General Curtain Wall Anchors – Head & Sill Anchor Bolts Control!
Rwl Curtain Wall vs. Storefront - General Curtain Wall Anchors – Intermediate/Slabs
Curtain Wall vs. Storefront - General Curtain Wall Anchors – Intermediate/Slabs Rwl “Wind Load” Anchor = Roller Support “Dead Load” Anchor = Pin Support
Limited Movement (1/8” max) Rwl Connections Control! Curtain Wall vs. Storefront - General Storefront Anchors – Head, Sill & Jambs Indirect Load Path to MWFRS
VSEC Seminar • March 26, 27 2008 • Curtain Wall vs. Storefront (General, Construction, Connection and Anchors) • Curtain Wall Performance – Wind, Snow, Seismic, Thermal, Impact, Blast • CW/SF Manufacturer’s Design Considerations (What We Need) • CW/SF Manufacturer’s Design Considerations (What We Get) • CW/SF Manufacturer’s Design Considerations (What We Assume) • CW Analysis, Rules of Thumb • Reference Information
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Wind Considerations • “Components and Cladding” provisions of ASCE 7 or Appropriate Building Code • Corner Zones are Important! $ • Industry Standard Deflection Limits: L/175 (span <13’ – 6”), L/240 + ¼” (span >= 13’ – 6”) • Accurate span information (dimensions), location of appropriate anchors! $$$$ • Aluminum Association ASD/LRFD Goal: Transfer all wind forces to MWFRS WL Reactions: 200 lbf to 3,500 lbf per anchor is typical
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Snow Considerations • Flat Roof Snow Loads + Drift Surcharge on Bladed Sunshades is (?) • Mullion Attachment Typical for Sunshades Goal: Transfer all snow forces to curtain wall system, then to MWFRS Effect of Snow on Reactions: Little effect to MWFRS
Ps Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Seismic Considerations • Racking of CW – Engineer of Record Must Provide Calculated Interstory Drift! • Controlled “Fallout” is the Standard (DFallout in ASCE 7)
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Seismic Considerations • Shear Forces per ASCE 7 • Calculate Fp = .4ap(Sds)Wp/(Rp/Ip) (1+2(z/h)) • Fp= Seismic force acting at centroid of mullion, with load evenly distributed along length of mullion • Fp acts the same as the wind load • Varies for perimeter anchors • Determine Deflection, Stress of frame member • Can be problematic for intermediate wind load anchors
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Seismic Considerations • Racking of CW • Shear Forces per ASCE 7 Goal: Transfer all seismic forces to MWFRS Seismic Reactions: Usually 50% of WL (200 lbf to 3,500 lbf per anchor is typical), but in-plane along weak axis
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Thermal/Vertical Movement Considerations • CW Mullions Buckle Easily • Must Account for all Vertical Movement (Thermal + Building Movement) $$$$ • Must Maintain Integrity of Perimeter Sealant Joint and Satisify Architectural Aesthetics • Sealant Joint RoT = ½ x Joint Width (Compression/Tension) • “Standard” System (no “Bells & Whistles”) good for +/- ¼” to ½” +/-!!
Total VM = Thermal + LL + CS + Creep + DL Glass contact controls Thermal Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast Thermal/Vertical Movement Considerations
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast Thermal/Vertical Movement Considerations
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast Thermal/Vertical Movement Considerations Thermal + Slab Movement
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast Thermal/Vertical Movement Considerations Goal: Avoid all thermal forces to MWFRS
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Impact Considerations • Large Missile <30’ (ASTM E1996 and 1886) • Small Missile >30’ (ASTM E1996/1886) • Large Missile Dependant on Wind Speed! • Identify Windborne Debris Region • Areas within one mile of the coastal mean high water line where the basic wind speed is equal to or greater than 110 mph and Hawaii • Areas where the basic wind speed is equal to or greater than 120 mph
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast
EFCO UNIVERSITY 2008 Part D. Missile Guidelines Large and Small Missile Impact per ASTM E 1996 - 06 ASTM E 1996 - 06 Missile Level Impact Speed Missile A (10) 2 gram steel balls 130 f/s (39.62 m/s) B 2 lb. 2 x 4 (1’-9”)lumber 50 f/s (15.25 m/s) C 4.5 lb 2 x 4 (4’) lumber 40 f/s (12.19 m/s) D 9 lb 2 x 4” (8’) lumber 50 f/s (15.25 m/s) E 9 lb. 2 x 4 (8’) lumber 80 f/s (24.38 m/s)
A (10) 2 gram steel balls 130 f/s (39.62 m/s) B 2 lb. 2 x 4 (1’-9”)lumber 50 f/s (15.25 m/s) C 4.5 lb 2 x 4 (4’) lumber 40 f/s (12.19 m/s) D 9 lb 2 x 4” (8’) lumber 50 f/s (15.25 m/s) E 9 lb. 2 x 4 (8’) lumber 80 f/s (24.38 m/s) EFCO UNIVERSITY 2008 Part D. Missile Guidelines Large and Small Missile Impact per ASTM E 1996 - 06 ASTM E 1996 - 06 Many projects will require level “C” or below Missile Level Impact Speed Missile
A (10) 2 gram steel balls 130 f/s (39.62 m/s) B 2 lb. 2 x 4 (1’-9”)lumber 50 f/s (15.25 m/s) C 4.5 lb 2 x 4 (4’) lumber 40 f/s (12.19 m/s) D 9 lb 2 x 4” (8’) lumber 50 f/s (15.25 m/s) E 9 lb. 2 x 4 (8’) lumber 80 f/s (24.38 m/s) EFCO UNIVERSITY 2008 Part D. Missile Guidelines Large and Small Missile Impact per ASTM E 1996 - 06 ASTM E 1996 - 06 Missile Level Impact Speed Missile
EFCO UNIVERSITY 2008 Part D. Missile Guidelines Large and Small Missile Impact per ASTM E 1996 - 06 ASTM E 1996 - 06 Basic Protection Enhanced Protection Assembly Height < 30 ft > 30 ft < 30 ft > 30 ft Wind Zone 1 C A D D Basic Wind Speed (MPH) 110 < Wind < 120 Wind Zone 2 C A D D Wind Zone 3 D A E D Wind Zone 4 D A E D
EFCO UNIVERSITY 2008 Part E. ASTM vs. Florida Building Code Large and Small Missile Impact per FBC/TAS 201 & 203 Small Missile Impact Cyclic Loading Identical to ASTM E 1886 Large Missile Impact Pass/Fail per FBC and/or Dade/Broward Counties, Florida The specimen shall resist the impact and cyclic loading with no tear formed longer than 5” and 1/16” in width through which air can pass. All specimens have to be tested at the Florida Approved Lab. TAS can NOT be tested at EFCO If any specimen fails to meet the requirements, the set of specimens is rejected. A retest of all (3) specimens is permitted.
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Impact Considerations • Large Missile <30’ (ASTM E1996 and 1886) • Small Missile >30’ (ASTM E1996/1886) • Large Missile Dependant on Wind Speed! • Identify Windborne Debris Region Goal: Prevent Loss of Glass Bite Reactions: Little to no effect to MWFRS due to impact
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Blast Considerations • Method 1: DoD UFC 04-010-01 = Prescriptive for “Low” or “Very Low” Level of Protection • Method 2: Design for Specific Blast Load and Specific Level of Protection
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast
Curtain Wall Performance Wind, Snow, Seismic/Drift, Thermal/VM, Impact and Blast • Blast Considerations Goal: Transfer Blast Loads to MWFRS Reactions: Up to 20,000 lbf per anchor (extremely short duration)! Wood, stud and masonry construction should be avoided for multi-lite or multi-span CW
VSEC Seminar • March 26, 27 2008 • Curtain Wall vs. Storefront (General, Construction, Connection and Anchors) • Curtain Wall Performance – Wind, Snow, Seismic, Thermal, Impact, Blast • CW/SF Manufacturer’s Design Considerations (What We Need) • CW/SF Manufacturer’s Design Considerations (What We Get) • CW/SF Manufacturer’s Design Considerations (What We Assume) • CW Analysis, Rules of Thumb • Reference Information
Curtain Wall Performance What We (Manufacturers) Need • Wind Considerations • Appropriate Code • Appropriate Exposure and Wind Speed • Accurate Span Information! • Appropriate Perimeter Condition (Structure) for “Higher” DP Regions
Curtain Wall Performance What We (Manufacturers) Need T V V
Curtain Wall Performance What We (Manufacturers) Need • Snow Considerations • Appropriate Code • Appropriate Ground Snow Load and Drift Surcharge
Curtain Wall Performance What We (Manufacturers) Need • Seismic/Drift Considerations • Appropriate Code • Must, Must, Must have calculated interstory drift! • Must have Sds (Design Spectral Response Acceleration, ASCE 7, Section 9.4.1.2) to calculate seismic shear.
Curtain Wall Performance What We (Manufacturers) Need • Thermal/VM Considerations • Total Vertical Deflection per Floor • Is the Total Vertical Deflection “Up and Down” or Different? • (The CW Manufacturer Will Add in the Thermal Movements)
Curtain Wall Performance What We (Manufacturers) Need • Impact Considerations • Appropriate Code (for DP) • Appropriate Wind Speed (Local Codes May Override Model BC) • Appropriate Perimeter Condition (Structure) for “Higher” DP Regions • Identify Windborne Debris Regions