Structural Steel Framing Options for Mid- and High Rise Buildings (I
Common Mid-Rise Structural Design Challenges – ELP...
Transcript of Common Mid-Rise Structural Design Challenges – ELP...
Common Mid-Rise Structural Design Challenges – ELP Solutions
Alberta WoodWorks Mid-Rise WorkshopFebruary 4, 2016
Engineered Lumber Products
= 0.8E = 1.3E, 1.5E, 1.55E
Batch Manufacturing Operation3‐1/2” x 8’ x 60’/64’ Billet
Laminated Strand Lumber (LSL)
ELP Tools & Services
There are Questions to answerThere are Opportunities to considerThen:
The process of Safe and Effective Delivery and Construction
How does a product go from Here to Here?
Topics of Conversation
Mid-Rise Structural Challenges:• Dimensional Stability (“Shrinkage”)• Increased Vertical Loads• Increased Lateral Loads
Solutions:• ELP Product Performance• Supplier Support
Questions?
Dimensional Stability – “Shrinkage”
Cumulative EffectsCross-grain shrinkage of particular concern
• Radial and tangential directions
Dimensional Stability – “Shrinkage”
Vertical Movement:• Combination of settlement, load deformation• Moisture changes shrinkage
Choose materials carefully
Also dependent on your Structural System
Platform or Flush Wall Framing?
Platform framing:• Wall plates• Rimboard• Joists
Flush wall framing:• Full height walls • Joists on Hangers
Platform Framing
• Rimboard (or blocking): permits distribution of loads to studs
• Top and bottom nailing critical to shear transfer
Flush Wall Framing• Direct Shear path –
nailing still critical• Vertical load path
relies on “in-line” studs or span capability of top plate
• Gypsum placement can be challenging
• Additional fire blocking between studs
Platform or Flush Wall Framing?
• “In-line” framing difficult to confirm on site.
• Very little gain in dimensional stability compared to I-joist and LSL platform framing
LSL Rim
Enhanced vertical load capacities and bending values
Stiffer element to assist in transferring load evenly to studs below
Avoid the need for in-line framing when designed adequately
But what about shrinkage?
Dimensional Stability – LSL Rim Board
EMC for lumber ~12%; for ELP ~10%
LSL(6‐8%)
EMC(10‐12%)
Lumber(16‐19%)
Discontinuous Grain
Dimensional Stability – LSL Rim Board
Relative study –worst-case conditions:• Measured depth:
• in yard (~10%)• saturated (>30%
MC),• redried to original
MC (~10%)0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2x10 Sawn Lumber Typical 9.25" LVL 9.25"TimberStrand®
Estimated Shrinkage in Rim(6 storeys, 30% - EMC 10%)
Dimensional Stability – LSL Wall Plates
Wall Plates • 3 per floor x 6 floors =
18 plates• ~1/16” shrinkage x
18 plates >1”
Keep LSL dry to avoid swelling
Photo Courtesy APEGBC
Dimensional Stability
Minimize moisture exposure through reduced open time. • Wall Panels• Floor Panels
Vertical Loads and Product Capacity
Wall Plates
Rim Board and Blocking
Wall Studs and Columns
Product Capacity - LSL Wall Plates
ASTM D5456 now allows Fcp determination for SCL based on proportional limit
0
200
400
600
800
1000
1200
1400
1600
No.1/No.2 1650Fb/1.5E 2100Fb/1.8E 1.3E 1.5E
SPF SPF MSR TimberStrand®
Plate Factored Bearing Resistance (psi)
Includes Phi=0.8, KB=1.25, and Kzcp=1.15 (lumber only)
Product Capacity - LSL Wall Plates
Effect of LSL plates (1.5E) on wall capacity:
Support of Vertical Loads – Rim BoardThis Way! Not This Way!
Rim Board Vertical Capacity
0
2000
4000
6000
8000
10000
12000
TJI® Joist 1‐1/8 TJ®Rimboard
1‐1/4" 1.3ETimberStrand®
LSL
1‐3/4" 1.55ETimberStrand®
LSL
Vertical Load Capacity (PLF) (11‐7/8")
Vertical Transfer Capacity (PLF) (11‐7/8") Factored Capacity (PLF)
Support of Concentrated Loads
This Way! Not This Way!
Vertical Capacity – LSL StudsFACTORED AXIAL RESISTANCE (PLF) - WALLS WITH 1.5E TimberStrand®® LSL BOTTOM PLATES
8' Wall Height Exterior Walls Interior Walls
Grade Stud 6" o.c. 8" o.c. 12" o.c. 16" o.c. 24" o.c. 6" o.c. 8" o.c. 12" o.c. 16" o.c. 24" o.c.
1.3E TimberStrand®®
2x4 8900 6585 4270 3115 1965 9260 6945 4630 3470 2315
2x6 19650 14735 9825 7365 4910 19650 14735 9825 7365 4910
1.5E TimberStrand®®
2x4 11340 8415 5490 4030 2570 11710 8780 5855 4390 2925
2x6 20400 15300 10200 7650 5100 20400 15300 10200 7650 5100
2x8 26890 20165 13445 10080 6720 26890 20165 13445 10080 6720
1.3E/1.5E TimberStrand®®
3" x 3‐½" 18160 13530 8900 6585 4270 18520 13890 9260 6945 4630
3" x 5‐½" 36880 27660 18440 13830 9220 36880 27660 18440 13830 9220
9' Wall Height Exterior Walls Interior Walls
Grade Stud 6" o.c. 8" o.c. 12" o.c. 16" o.c. 24" o.c. 6" o.c. 8" o.c. 12" o.c. 16" o.c. 24" o.c.
1.3E TimberStrand®®
2x4 7530 5550 3570 2580 * 7950 5960 3975 2980 1985
2x6 18700 14025 9350 7005 4555 18700 14025 9350 7010 4675
1.5E TimberStrand®®
2x4 9500 7025 4550 3315 340 9920 7440 4960 3720 2480
2x6 20400 15300 10200 7650 5100 20400 15300 10200 7650 5100
2x8 26890 20165 13445 10080 6720 26890 20165 13445 10080 6720
1.3E/1.5E TimberStrand®®
3" x 3‐½" 15480 11505 7535 5550 3570 15900 11925 7950 5960 3975
3" x 5‐½" 36880 27660 18440 13830 9220 36880 27660 18440 13830 9220
10' Wall Height Exterior Walls Interior Walls
Grade Stud 6" o.c. 8" o.c. 12" o.c. 16" o.c. 24" o.c. 6" o.c. 8" o.c. 12" o.c. 16" o.c. 24" o.c.
1.3E TimberStrand®®
2x4 6340 4640 2955 * * 6790 5090 3395 2545 1695
2x6 17640 13200 8660 6390 4125 17640 13230 8820 6615 4410
1.5E TimberStrand®®
2x4 7930 5840 3755 2010 * 8380 6285 4190 3140 2095
2x6 20400 15300 10200 7650 5100 20400 15300 10200 7650 5100
2x8 26890 20165 13445 10080 6720 26890 20165 13445 10080 6720
1.3E/1.5E TimberStrand®®
3" x 3‐½" 13120 9725 6340 4645 2955 13580 10185 6790 5090 3395
3" x 5‐½" 35280 26460 17640 13200 8660 35280 26460 17640 13230 8820
* Deflection limit exceeded by wind load See TB‐754
Vertical Capacity – LSL Studs
Possible solution: 3” solid LSL stud
Wider spacing – easier on trades
Eliminate mid‐height blocking
Shear nailing advantages
Lateral Loading
• Transfer of wall shear loads through the floor depth
• Shear wall nailing
Product Capacity – LSL Rim
1-⅛” rimboard may not be adequate for mid-rise applications
Diaphragm Nailing Plate Nailing
Lower strength and density:
• Limited nail spacing (6” o.c. typical)
• Higher likelihood of splitting when toe or edge nailed
Product Capacity – LSL Rim• 1‐1/4” or thicker
allows for 2 rows at tighter spacing
• LSL thicknesses up to 3‐1/2” used
• See manufacturer’s code reports or published guidelines for allowable spacing
• Beware of substitution
Lateral Loads - LSL Shear Walls
Tight Fastener spacing – even in wind‐governed designs
3‐4” commonly specified; 2” in SPF occasionally
1.5E LSL or greater needed for these spacings
Beware of substitution
3-1/2’’ LSL Rim
Large “side loads” invite potential issues
• Correct connection pattern?• Installed beam correctly?
1-piece beams vs multi-ply
1-piece beams vs multi-ply
ConnectionsGoal: Effective load transfer
to all plysAvoid “slippage”
1-piece beams vs multi-ply
ConnectionsPotential conflict with other framing
It takes time and extra materials to assemble a multi-ply beam!
A quicker, more reliable installation process:• 1-piece PSL or• 3-1/2” LSL
1-piece beams vs multi-ply
Manufacture–only• Attractive price• limited support
Engineered Lumber Tools & ServicesTo achieve this
SF tools MF expertise• Higher material cost • Reliability & Savings in
overall project
Range of Products and Services
Software for Design and Fabrication
Software for Design and Fabrication
Video
People behind the Products
Key questions to ask about your ELP supplier:• Do they have the expertise to offer design service
appropriate for large multi-family structures?• Can they partner with you at the design stage to
resolve project issues up front?• Will they be there to assist as the project
progresses?• Will they help you hold your specification?
Adding Value at the Bid StageSuccessful builders have told us:• Including performance criteria and product
specifications in bid requirements increases the chances of:
• Delivery of material and construction meeting the intent of the design team and owner
• Avoiding the race to the bottom in accepting inferior low-ball bids can cost more in the long run
• Items considered key for quality: • List years experience, qualifications, work examples.
Opportunities – Roof/Wall Panels
Opportunities – Hybrid Panels
Hybrid Panel alternatives
Opportunities – Hybrid PanelsHybrid Panel alternatives
In Conclusion….
• LSL provides significant benefit in addressing shrinkage and increased loading in mid-rise structures
• Partnering with an experienced supplier enhances the possibility of a successful project
Questions?