Copyright Materials WFCM 2015 Significant Changes and American Wood Council

American Wood Council www.awc.org

WFCM 2015 Significant Changes and

Introduction to High Wind Guides (STD333)

Lori Koch, PE

Manager, Educational Outreach

American Wood Council

Copyright Materials

This presentation is protected by US and International

Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of AWC is prohibited.

© American Wood Council 2016

2

Copyright © American Wood Council.

All rights reserved.

1


•

•

The American Wood Council is a

Registered Provider with The American

Institute of Architects Continuing

Education 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 request.

•

This course is registered with AIA CES for continuing professional education.

As such, it does not include content 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 of handling, using, distributing, or dealing in any material or product.

•

Questions related to specific materials, methods, and services will be 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 l 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 solutions offered in the High Wind Guide will also be presented.



2


Learning Objectives

1.

Be familiar with provisions of the 2015 WFCM and High Wind

Guides and relevant references in the 2015 International

2.

3.

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

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

Understand how to appropriately apply tables in both the

WFCM and High Wind Guides to determine prescriptive minimums.

Polling Question

1. What is your profession?

a) Architect c) Code Official d) Building Designer e) Other

6



3


Polling Question

1b.

Did you watch the recommended program

(STD315 – 2012 WFCM Changes) prior to today’s a) Yes b) No

7

Why design for high wind speeds?

Tornado and hurricane resistance!



Structure on left can withstand 250 m.p.h. winds and a 15 lbs.

2” x 4” missile fired at the structure at 100 m.p.h.!

Go to: https://www.fema.gov/wall-section s-passed-previous-missile-impact-tests

8

4


WFCM and IRC/IBC

•

•

•

2001 WFCM → 2003, 2006, 2009 IRC/IBC

2012 WFCM → 2012 IRC/IBC

2015 WFCM → 2015 IRC/IBC

WFCM and IRC

•

•

•

R301.1.1 Alternative Provisions

WFCM permitted

•

•

•

•

•

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



10

9

5


WFCM and IBC

•

Chapter 16 – Determination of Wind Loads

Section of IBC (1609.1.1)

•

•

•

•

Exception: residential structures per

WFCM

Not used for structures on hills, ridges, or escarpments

Chapter 23 – Wood design

• •

2301.2 & 2309 conventional construction

2015 IBC

11



12

6


2015 IBC

13

13

2015 IBC

•

•

•

Applications

•

Single-story

•

•

Slab-on-grade

L and W < 80’

Examples

•

Restaurants

•

Office Buildings

Design

•

•

Lateral

Gravity



14

7


Polling Question

2.

The 2015 WFCM can be used to design some commercial buildings per the 2015 IBC b) False

15

WFCM

•

•

• •

•

Chapter 1: General

Chapter 2: Engineered Design

•

General outline Chapters 2-3

•

Connections

•

•

Floor systems

Wall systems

•

Supplement



16

8


WFCM Chapter 1

17

WFCM Chapter 1

•

WFCM Table 1 –

Applicability

Limitations



NEW!

18

9


WFCM Chapter 1

•

•

Building dimensions mean roof height (MRH) < 33 ft

•

• building length and width < 80 ft

S

T

O

R

Y

T

W

O

S

T

O

R

Y

O

N

E

S

T

O

R

Y

T

H

R

E

E

Average grade

< 7

1 2

< 7

1 2

< 7

1 2

M R H

M R H

M R H

19

Chapter 1: General



20

10


WFCM Chapter 1

•

•

•

•

•

Items not addressed include ancillary structures such as:

Decks

Balconies

Carports

Porches

Chapter 2: Engineered

•

Loads and load path

•

Continuous

• y connections

•

Always ends in supporting soil

•

Building has hundreds of load paths

Source: FEMA

22



21

11


WFCM Chapter 2: Engineered


23



24

12



Wind uplift

Load


25



26

13


WFCM Chapter 3: Prescriptive


•

WFCM Table 3.1 –

Prescriptive

Limitations

27

28



14



2015 WFCM Changes

•

Header Spans Supporting Roof and Ceiling New

29



30

15


2015 WFCM Changes

•

Rafters/Ceiling Joists – Brittle Finishes

New

31

2015 WFCM Changes

•

•

New Southern Pine Design Values

Lumber Framing Spans

•

•

•

•

Rafters

Studs

Headers

Revised

32



16


2015 WFCM High Wind Guides

Exposure B: 115 – 150 MPH

Exposure C: 115 – 160 MPH

33


•

Prescriptive Solutions for:

•

Walls

• •

•

Roofs

34



17


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

35




36

18


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

Polling Question

3.

The WFCM High Wind Guides have no additional limitations beyond those imposed in the scope of a) True b) False

37

38



19



•

•

Wall-to-wall connections:

Or per manufacturer’s specifications for proprietary systems

Design Example

Assumptions

•

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

39

20


Design Example

L=36’ W=30’ L/W=1.2

Interpolated Spacing = 47”

41

Design Example

Wall Heights = 8’ OK



42

21


Design Example

Top Plate Splice Nailing Requirements

L=36’ – 14 nails

W=30’ – 12 nails

Design Example

43



44

22


Design Example

Uplift = 203 lbs (interpolated)

45

Design Example



46

23


Design Example

47

Design Example

Max.

Window Width = 2.5’

Lateral = 161 lbs (interpolated)



48

24


Design Example

Max.

Window Width = 2.5’ Max.

Door = 5’

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

49

WFCM High Wind Guide - Prescriptive

Assumes perforated shear wall with hold-downs only at the ends

WFCM HWG use ONLY perforated method

50



25



Load Bearing Walls

Second Floor

Using 6” edge/ 12” field spacing:

L/W = 36

'

/30

'

= 1.2

Interpolated = 36.2% = 13

'

Available = 23.5

'

OK

Hold Down Capacity = 4,360 lb

51


Load Bearing Walls


L/W = 36

'

/30

'

= 1.2

Interpolated = 59.8% = 21.5

'

Available = 21

'

NG!


L/W = 36

'

/30

'

= 1.2

Interpolated = 46.8% = 16.9

'

Available = 21

'

OK


Combined Hold-down

5,900 + 4,360 = 10,260 lb

52



26



Gable End – Second Floor


L/W = 36

'

/30

'

= 1.2

Interpolated = 47.4% = 14.2’

Openings = 15.8’


Gable End – First Floor


L/W = 36

'

/30

'

= 1.2

Interpolated = 75% = 22.5’


Combined Hold-down

4,360 + 4,360 = 8,720 lb

53


Controlling Hold ‐ Down – 1 st

10,260 lb > 8,720 lb floor

2 nd floor hold downs require 4,360 lb capacity

54



27



Uplift = 300 lbs (interpolated)


55

Ridge Strap = 274 plf (interpolated)



56

28


Prescriptive Solutions

•

•

WFCM and High Wind Guides specify capacity requirements for engineered connectors, straps, and hold downs

M f t id individual components it f

Polling Question

4.

The 2015 WFCM HWG uses the ____________ method for shearwall design.

b) Perforated c) Force Transfer Around Openings (FTAO) d) All of the above

57

58



29


WFCM Changes

•

White paper http://www.awc.org

/pdf/2015 WFCM-

Changes-Web.pdf

What’s Changed?

59

Technical Articles

•

•

Structure Magazine

2015 NDS

•

January 2015

•

•

•

•

2015 WFCM

February 2015

2015 SDPWS

July 2015

What’s Changed?



60

30


Polling Question

5.

The WFCM HWG specifies ___________ for connections such as ridge straps, uplift straps, and a) Minimum capacity requirements b) Quantities c) Manufacturer name brands d) Model numbers

Questions?

•

This concludes The American Institute of Architects Continuing

Education Systems Course info@awc.org

www.awc.org

61

62



31

Copyright Materials WFCM 2015 Significant Changes and American Wood Council

WFCM 2015 Significant Changes and

Introduction to High Wind Guides (STD333)

Why design for high wind speeds?

Structure Magazine

Related documents

Products

Support

Copyright Materials WFCM 2015 Significant Changes and American Wood Council

WFCM 2015 Significant Changes and

Introduction to High Wind Guides (STD333)

Why design for high wind speeds?

Structure Magazine

Related documents

Add this document to collection(s)

Add this document to saved

Suggest us how to improve StudyLib