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?