WFCM 2015 Significant Changes and Introduction to High Wind … · 2016. 4. 13. · Engineering concepts from the 2015 Wood Frame Construction Manual (WFCM), used to develop the 2015

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WFCM 2015 Significant Changes and Introduction to High Wind Guides (STD333)

Lori Koch, PEManager, Educational Outreach American Wood Council

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© American Wood Council 2016

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• The American Wood Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES)

• This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed toEducation Systems (AIA/CES),

Provider # 50111237.

• Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon

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that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner ofhandling, using, distributing, or dealing in any material or product.

• Questions related to specific materials, methods, and services will be addressed at the conclusion of this

request.addressed at the conclusion of this presentation.

Description

Engineering concepts from the 2015 Wood Frame Construction Manual (WFCM), used to develop the 2015 WFCM Hi h Wi d G id ill b d l2015 WFCM High Wind Guides, will be covered, along with updates on changes to the 2015 WFCM. The WFCM and High Wind Guides provide designers with time-saving tools using prescriptive solutions (based on structural engineering principles) for wood structures to resist anticipated wind loads. Example problems showing how to apply tabular solutionsproblems showing how to apply tabular solutions offered in the High Wind Guide will also be presented.



Learning Objectives

1. Be familiar with provisions of the 2015 WFCM and High Wind Guides and relevant references in the 2015 International Residential Code (IRC) and 2015 International Building CodeResidential Code (IRC) and 2015 International Building Code.

2. Be familiar with changes in the 2015 WFCM and how they impact structural design.

3. Understand how roof, floor, and wall assemblies and connections interact as part of a wind uplift and lateral force resisting system.

4 Understand how to appropriately apply tables in both the4. Understand how to appropriately apply tables in both the WFCM and High Wind Guides to determine prescriptive minimums.

Polling Question1. What is your profession?

a) Architect

b) E ib) Engineer

c) Code Official

d) Building Designer

e) Other

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Polling Question1b. Did you watch the recommended program

(STD315 – 2012 WFCM Changes) prior to today’s webinar?webinar?

a) Yes

b) No

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Why design for high wind speeds?Tornado and hurricane resistance!

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Structure on left can withstand 250m.p.h. winds and a 15 lbs.2” x 4” missile fired at thestructure at 100 m.p.h.!Go to: https://www.fema.gov/wall-sections-passed-previous-missile-impact-tests



WFCM and IRC/IBC

• 2001 WFCM → 2003, 2006, 2009 IRC/IBC

• 2012 WFCM → 2012 IRC/IBC

2015 WFCM 2015 IRC/IBC• 2015 WFCM → 2015 IRC/IBC

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WFCM and IRC

• R301.1.1 Alternative Provisions

• WFCM permitted

R301 2 1 1 Wind Design• R301.2.1.1 Wind Design

• For bldgs. where wind design is required or > 110 mph use one or more of the following:

• WFCM

• ICC 600 (newly referenced)

• ASCE 7

• IBC

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WFCM and IBC

• Chapter 16 – Determination of Wind Loads Section of IBC (1609.1.1)

• Wind loads in accordance with ASCE 7Wind loads in accordance with ASCE 7

• Exception: residential structures per WFCM

• Not used for structures on hills, ridges, or escarpments

• Chapter 23 – Wood design

• 2301 2 & 2309 conventional• 2301.2 & 2309 conventional construction

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2015 IBC

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2015 IBC

1313

2015 IBC

• Applications

• Single-story

• Slab-on-grade

• L and W < 80’

• Examples

• Restaurants

• Office Buildings

• Design

• Lateral

• Gravity

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Polling Question2. The 2015 WFCM can be used to design some

commercial buildings per the 2015 IBC

a) Truea) True

b) False

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WFCM

• Chapter 1: General

• Chapter 2: Engineered Design

• Chapter 3: Prescriptive Design• Chapter 3: Prescriptive Design

• General outline Chapters 2-3

• Connections

• Floor systems

• Wall systems

• Roof systemsy

• Supplement

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WFCM Chapter 1

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WFCM Chapter 1

• WFCM Table 1 –Applicability Limitations

NEW!

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WFCM Chapter 1

• Building dimensions

• mean roof height (MRH) < 33 ft

n mbe of sto ies < 3

ONE

STOR

1 2< 7

M R H

• number of stories < 3

• building length and width < 80 ft

RY

1 2

1 2

M R H

TWO

STORY

T

< 7

< 7

Average grade

M R H

THREE

STORY

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Chapter 1: General

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WFCM Chapter 1

• Items not addressed include ancillary structures such as:

• Decks

• Balconies

• Carports

• Porches

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• Loads and load path • Continuous• Continuity created by

Chapter 2: Engineered

y yconnections

• Always ends in supporting soil• Building has hundreds of load

paths

22Source: FEMA



WFCM Chapter 2: Engineered

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Wind uplift Load

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WFCM Chapter 3: Prescriptive

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• WFCM Table 3.1 –Prescriptive Limitations

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2015 WFCM Changes

• Header Spans Supporting Roof and Ceiling New

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2015 WFCM Changes

• Rafters/Ceiling Joists – Brittle Finishes

New

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2015 WFCM Changes

• New Southern Pine Design Values• Lumber Framing Spans

J i t• Joists

• Rafters

• Studs

• Headers

Revised

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2015 WFCM High Wind Guides

Exposure B: 115 – 150 MPH

Exposure C: 115 – 160 MPH

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• Prescriptive Solutions for:

• Walls

• Floors• Floors

• Roofs

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2015 WFCM High Wind Guides (140 MPH)

• Additional limitations beyond WFCM

• Maximum opening height = 6’-8” (can go up to 8’ with exception)

• Require exterior walls to be fully sheathed

• Building Aspect Ratio Limits for 140 MPH: 1.0 ≤ (L/W) ≤ 2.75

• Can go as high as 3:1 at lower speeds

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Alternative Fasteners

• 2015 WFCM only specifies smooth shank nails

• Sources for info on alternative fasteners

• Manufacturer

• ICC-ES: ESR 1539 Manufacturer’s Equivalency For Nails

• Per engineer’s calculation

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Polling Question3. The WFCM High Wind Guides have no additional

limitations beyond those imposed in the scope of the WFCMthe WFCM

a) True

b) False

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2015 WFCM High Wind Guides• Wall-to-wall connections:

• Or per manufacturer’s specifications for proprietary systems

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Design ExampleAssumptions

• 140 mph (700-yr, 3-second gust) Exposure B

• L=36’

• W=30’

• 5/12 roof pitch

• Top plate to ridge = 6.25’

• 2-story

• 8’ wall height

• 6’8” door height

• 4’ window height

• Wood Structural Panel Exterior Sheathing w/ Gable End Walls 40



Design Example

L=36’ W=30’ L/W=1.2

Interpolated Spacing = 47”

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Design ExampleWall Heights = 8’ OK

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Design ExampleTop Plate Splice Nailing Requirements

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L=36’ – 14 nails

W=30’ – 12 nails

Design Example

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Design Example

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Uplift = 203 lbs (interpolated)

Design Example

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Design Example

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Design ExampleMax. Window Width = 2.5’

48Lateral = 161 lbs (interpolated)



Design ExampleMax. Window Width = 2.5’ Max. Door = 5’

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Window Uplift = 330 lbs (interpolated); Lateral = 161 lbs (interpolated)

WFCM High Wind Guide - Prescriptive

Assumes perforated shear wall with hold-downs only at the endsWFCM HWG use ONLY perforated method 50




Load Bearing Walls

Second FloorUsing 6” edge/ 12” field spacing:L/W = 36'/30' = 1.2Interpolated = 36.2% = 13'Available = 23.5' OKHold Down Capacity = 4,360 lb

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Load Bearing Walls

First FloorFirst FloorUsing 6” edge/ 12” field spacing:L/W = 36'/30' = 1.2Interpolated = 59.8% = 21.5'Available = 21' NG!

Using 4” edge/ 12” field spacing:L/W = 36'/30' = 1.2Interpolated = 46.8% = 16.9'Available = 21' OKHold Down Capacity = 5,900 lb

Combined Hold-down5,900 + 4,360 = 10,260 lb

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Gable End – Second FloorUsing 6” edge/ 12” field spacing:L/W = 36'/30' = 1.2Interpolated = 47.4% = 14.2’Openings = 15.8’Hold Down Capacity = 4,360 lb

Gable End – First FloorUsing 6” edge/ 12” field spacing:L/W = 36'/30' = 1.2Interpolated = 75% = 22.5’Openings = 7 5’Openings = 7.5Hold Down Capacity = 4,360 lb

Combined Hold-down4,360 + 4,360 = 8,720 lb

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Controlling Hold‐Down – 1st floor10,260 lb > 8,720 lb

10 260 lb can be used at all 4 corners on 1st floor10,260 lb can be used at all 4 corners on 1st floor

542nd floor hold downs require 4,360 lb capacity




Uplift = 300 lbs (interpolated)

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Ridge Strap = 274 plf (interpolated)

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Prescriptive Solutions• WFCM and High Wind Guides specify

capacity requirements for engineered connectors, straps, and hold downs

M f t id it f• Manufacturer provides capacity of individual components

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Polling Question4. The 2015 WFCM HWG uses the ____________

method for shearwall design.

a) Segmenteda) Segmented

b) Perforated

c) Force Transfer Around Openings (FTAO)

d) All of the above

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WFCM Changes

• White paper

http://www.awc.org/pdf/2015 WFCM-Changes-Web.pdf

59What’s Changed?

Technical Articles

• Structure Magazine• 2015 NDS

• January 2015

• 2015 WFCM• February 2015

• 2015 SDPWS• July 2015

60What’s Changed?



Polling Question5. The WFCM HWG specifies ___________ for

connections such as ridge straps, uplift straps, and hold downs.hold downs.

a) Minimum capacity requirements

b) Quantities

c) Manufacturer name brands

d) Model numbers

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• This concludes The American Institute of Architects Continuing Education Systems Course

Questions?

[email protected]

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Documents

WFCM 2015 Significant Changes and Introduction to High Wind … · 2016. 4. 13. · Engineering concepts from the 2015 Wood Frame Construction Manual (WFCM), used to develop the 2015