Wood Connections

Sam Hensen, P.E.Branch Engineering Manager

2

Must provide sufficient capacity to transfer loads to supporting membersUtilize fastener spacing which does not cause splitting of the lumberHold the wood members in a manner such that shrinkage/swelling cycles do not induce splitting across the grainMinimize regions that might collect moistureMinimize the potential for tension perpendicular to grain stressesChoose a finish on the connector appropriate for the application

Concepts of Well Designed Connections

3

ProductionWill the last part look like the first part?Will the part be the same in San Antonio and Dallas, Florida, Virginia?

Accuracy of rated loads To what standard?

What does approved sources mean for alternate products not listed in the building code?

Concepts of Well Designed Connections

Alternative Materials

IBC 104.11 Alternative Materials, design and methods of construction and equipmentThe provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety.

Alternative Materials

IBC 104.11.1 Research ReportsSupporting data, where necessary to assist in the approval of materials or assemblies not specifically provided for in this code, shall consist of valid research reports from approved sources.

ICC-ES and IAPMO-ES

Lab performs

test

Independent Agency

Witnesses Test

IndependentAgency

issues Lab report

Lab report & Calculations submitted to Evaluation

AgencyEvaluation

Agency issues Code

Report

Approval process

Lab does test

Lab issues Report

Evaluation Agency establishes

minimum QA and QC requirements

Evaluation Agency

Performs biannual audits

Acceptance Criteria Established through consensus process

Building Official Confident in

product evaluation

IAPMO-ES

Accredited by the American National Standards Institute (ANSI)Began evaluating plumbing and mechanical productsApproved to evaluate structural productsIAPMO-ES performs technical evaluations of building products, components, methods, and materials. Issues reports on code compliance

Made available free of charge to code officials, contractors, specifiers, architects, engineers, and anyone else with an interest in the building industry and construction.

IAPMO-ES evaluation reports provide evidence that products and systems meet code requirements.

ICC-ES

ICC-ES is a nonprofit, public-benefit corporation. (Not ICC)

ICC-ES performs technical evaluations of building products, components, methods, and materials.

Issues reports on code complianceMade available free of charge to code officials, contractors, specifiers, architects, engineers, and anyone else with an interest in the building industry and construction.

ICC-ES evaluation reports provide evidence that products and systems meet code requirements.

ICC-ES/IAPMO-ES

Main purpose evaluation reports is to assist those enforcing model codes to determine whether a given subject complies with those codesAn evaluation report is not to be construed as representing a judgment about aesthetics or any other attributes not specifically addressed in the reportNot an endorsement or recommendation for use of the subject of the reportApproval for use of the subject of the report is the prerogative and responsibility of the Code Official

ICC-ES Quality Assurance

Applicants for ICC-ES evaluation reports are required to provide quality documentation for the products to be covered in the report

At the time of the qualifying inspection, the inspector will check the completeness of the documentation

The inspector will also verify that the manufacturer is actuallyoperating in accordance with the quality documentation, and that the product being manufactured is consistent with the product information submitted to ICC-ES.

For cases where the report holder and the manufacturer are different, and the manufacturer is not an additional listee on the report, the report holder and the manufacturer will have to jointly fill out and submit

ICC-ES Quality Assurance

Prior to publication of a new ICC-ES evaluation report

ICC-ES must have objective evidence that a qualifying inspection of the facilities manufacturing products to be recognized in the evaluation report has been successfully completedThe qualifying inspection will verify that the manufactured products are consistent with the recognized evaluation reportThe manufacturer has documented and effectively implemented a quality system that meets all requirements of ICC-ES Agencies must be accredited for inspections of the product in question

ICC-ES Quality Assurance

IAPMO-ES Quality Assurance

IAPMO-ES Quality Assurance

15

The Process of Selecting the Appropriate Connector

16

What is the application?

CONCRETE ANCHORS POST BASES POST CAPS FACE MOUNT HANGERS

TOP FLANGE HANGERS

PLATED TRUSS MASONRY STRAPS AND TIES

17

What are the Size and Species of the Members?

Dimension Lumber Sizes (2X4, 2X6, etc )

Engineered Wood Sizes (Glulam, LVL, I-joist, etc )

Member Species (DF, SP, SPF, HF)

Fastened to Steel, Concrete, or Block

18

How are the members oriented relative to one another?

19

What are the type of Fasteners that will be used?

SDS SCREWSBOLTS NAILS

20

What is the Load Requirement for the Connection?

Gravity Load (LL, SL, RL, WL)?

Uplift Load?

Lateral Load?

21

What are the costs?

Website

http://www.strongtie.com/literature/pricebook/

22

What is the appropriate finish for the connector (if applicable)?

23

Finishes Available

24

Concerns with PTW

25

IBC - Fasteners

26

IRC - Fasteners

27

Technical Assistance Available!

1-800-999-5099

28

Where did all of these products come from?

Building Code Driven

Specifier Driven

Installer Driven

29

BUILDING CODES

30

Load Path Requirements

IBC Section 2304.9.6

Where wall framing members are not continuous from foundation sill to roof, the members shall be secured to ensure a continuous load path. Where required, sheet metal clamps, ties or clips shall be formed of galvanized steel or other approved corrosion-resistant material not less than 0.040-inch nominal thickness (20 ga)

31

Load Path Code Requirement

IBC Section 1604.4 Analysis Any system or method of construction to be used shall be based on a rational analysis in accordance with well-established principles of mechanics. Such analysis shall result in a system that provides a complete load path capable of transferring loads from their point of origin to the load-resisting elements.Every structure shall be designed to resist the overturning effects caused by the lateral forces specified in this chapter.

32

How do we determine the

allowable loads?

33

IBC 2304.9.3Joist hangers and framing anchors

Connections depending on joist hangers or framing anchors, ties and other mechanical

fastenings not otherwise covered not otherwise covered are permitted where approved. The

vertical loadbearing capacity, torsional moment capacity, and deflection characteristics of joist

hangers shall be determined in accordance with Section 1716.1

34

Connector Allowable Load Determination

Lowest Value from 3 Tests of either 1/8Deflection Limit or

Ultimate/3 Limit

Code Allowed Fastener and Bearing

Calculations

Steel Capacity (strap type products)

IBC 1716.1Requires that the connector allowable load be determined from the lowest of the following

Building CodeRequirements

Lumber Capacity

35

Determining NDS BOLT Calculation Limitations

CAPACITY OF A BOLT IN LUMBER IS A FUNCTION OF:

1. Bolt Diameter/length in members

2. Lumber S.G.

3. Fastener Grouping

4. Edge/End distances

5. Orientation of load to lumber grain

6. Number of members being attached

7. Duration of Load

8. Steel Strength when connecting metal to wood

Bolt Yield Limit Equations

Single vs Double Shear

Edge/End distances

39

Determining NDS Fastener Calculation Limitations

CAPACITY OF A SINGLE NAIL IS A FUNCTION OF:

0 1 ½ 3 3¼ 3½

1. Nail Diameter

2. Nail Length in member

3. Nail bending yield strength

4. Lumber S.G.

5. Steel Thickness

6. Steel Tensile Strength

10dX1½

8dX1½

10d Common

16d Sinker

16d Common

0.162

0.148

0.148

0.148

0.131

10.2.3 Design of Metal Parts

41

Up

lift

Do

wn

loa

d

Continuous Load Path

42

Examine an HTU210

HTU210Max Nailing Requires

32-16d Common Nails

Allowable Floor Load = 4705 lbs

43

Nail capacity calc from the NDS

32 Nails x 147 lbs = 4705 lbs

44

Load Duration Concept

Nail calculations are at a normal load duration

What is a normal Load Duration?

Weight Time Holding

5 lbs 120 seconds

20 lbs 30 seconds

50 lbs 10 seconds

100 lbs 2 seconds

45

Load Duration Factors

ApplicationDuration Factor

Duration Assumption

Floor Load (D+L)

1.0 10 Years

Snow Load 1.15 3 Months

Roof Live Load

1.25 7 Days

Wind/EQ Load

1.60 10 Minutes

46

Nail Limitations

Floor: 1.00 X 4705 = 4705 lbs (100)

Snow: 1.15 X 4705 = 5411 lbs (115)

Roof: 1.25 X 4705 = 5881 lbs (125)

Wind: 1.60 X 4705 = 7528 lbs (160)

Each Value is compared against test limitations

32 Nails X 127 = 4705 lbs (100)

Calculated Nail Values

47

Why Test if Calcs show it works?

48

Determining Test Limitations

Test #1

1/8 Ult/3

Test #2

1/8 Ult/3

Test #3

1/8 Ult/3

49

What s the Factor of Safety?

Item Factor of Safety

Connectors (except straight straps) 3.0

Straight Strap Connectors Per steel design manuals

Shear Walls 2.0

Anchor Systems Products 4.0

50

Floor: 1.00 X 4705 = 4705 lbs (100)

Snow: 1.15 X 4705 = 5411 lbs (115)

Roof: 1.25 X 4705 = 5881 lbs (125)

Wind: 1.60 X 4705 = 7528 lbs (160)

Nail Limitations

Test Limitation on HU210 = 5995 lbs (Steel tore at 17985 lbs)

Test Limitation

5995 lbs

5760 lbs *

5345 lbs *

* ANSI/TPI limitations on truss chords limit listed values Reference T-ANSITPI technical bulletins

51

Simpson Test Labs

52

Simpson Connector Test Lab

53

Code Bearing Requirements

IRC R502.6 BearingThe ends of each joist, beam or girder shall have not less than 1.5 of bearing on wood or metal and not less than 3 on masonry or concrete except where supported on a 1 by 4 ribbon strip and nailed to the adjacent stud or by the use of approved joist hangers

IBC 2308.8.1 BearingExcept where supported on a 1 by 4 ribbon strip and nailed to the adjoining stud, the ends of each joist shall not have less than 1 1/2 of bearing on wood or metal, or less than 3 on masonry.

54

What is a Ribbon Strip?

55

56

1 2

3 4

1½ of bearing?

57

58

59

Straps and angles are not hangers!

60

Solid Sawn LumberSolid Sawn Lumber

Plated TrussPlated Plated TrussTruss

Composite Wood I -joist

Composite Composite Wood Wood II --joistjoist

Structural Composite

Lumber

Structural Structural CompositeComposite

LumberLumber

HANGERS

61

HANGER TYPES

FACE MOUNTTOP FLANGESLOPED & SKEWEDOPTIONSSPEC NON-CATALOGCUSTOMS

62

Nail Hole Identification

Fill all round holes

Triangle holes optional for additional load

Diamond holes optional for ease of installation

63

Round Nail HolesRound Nail Holes

Fill all round and obround nail holes Exception to the rule: Strap hangers and straps

64

General Installation of Connectors

Manufacturers face the facts:Proper nails are not always usedSimpson provides tables that have factors for use of some alternate size nailsAlso reduction for inadequate nail penetration (10 nail diameters):1-3/8 for 8d1-1/2 for 10d1-5/8 for 16dDepth of connected members important (e.g. reduction for 3-inch nail in 2x member)

65

Alternate Nails

Can NOT substitute 1½ nails in double shear hangersLUS, MUS, HUS, HHUS, HGUS

Top Flange Hangers, hurricane ties and any others not applicable to this table

66

Prevent Torsional Effects

IBC 1715.1.3 requires torsion to be factored into the capacity of a hanger or provide restraint against torsion

67

68

Header Nails should find lumber or a reduction in capacity must be calculated.

Hanger Height Considerations

69

Joist or truss should not be more than 1/8 from the Header

Too much gap

Short Cut Joist or Trusses

70

Hanger not Plumb

71

Hanger Over Spread

72

Field Bent Flanges

73

Field Welded

74

4-1 segments for < 3280 lbs

6-1 segments for 3280 lbs to 4855 lbs

Don t recommend welding thicknesses less than 14 Ga.

Welded Applications

75

What are we Connecting To?

76

77

HU Hangers to Block/Concrete Walls

78

CONNECTOR SELECTOR

79

Up

lift

Lateral

Continuous Load Path

80

Overall Wind Effects

Roof suction (uplift)

Suction on side and back walls

Positive (inward) pressure on windward walls

Flow patternPressure distribution

81

1) Sheathing

2) Truss/Rafter to Top Plate

3) Top Plate to Stud

4) Header to Studs

5) Stud to Stud

6) Stud to Sill Plate

7) Sill Plate to Foundation

23

5

6

Uplift Load Path

1

7

4

82

Has Anyone Seen My Roof?

83

84

Truss to Wall Connections

85

Girder to Wall Connections

86

Remember the Contractor!

Every other truss and stud will line up!

Don t end up with this!

87

When Framing Aligns

H10STruss to studAllows for offsetWorks for masonry

88

Overlapping Connectors

24 & 16 O.C.

Every other truss/rafter will line up with a stud

2 options:

Tie truss/rafter directly to stud

Use alternate connectors

Remember the H10S

89

90

Top Plate to Wall Connectors

91

Headers to Studs

92

93

Floor to Floor Connectors

94

95

Stud to Sill Plate

96

97

Sill Plate to Foundation

98

MAS Installed

99

MAS Installed

100

Lateral

Continuous Load PathD

ow

nlo

ad

101

Ceiling Joists an Rafter Connections Continuous Tie Across Building

Ceiling joist tie prevents walls from spreading under downward load on rafters

102

R802.3.1 Ceiling joist and rafter connections

Ceiling joists and rafters shall be nailed to each other in accordance with Table R802.5.1(9), and the rafter shall be nailed to the top wall plate in accordance with Table R602.3(1).

103

Table R802.5.1.9

104

Table R802.5.1.9 Footnotes

a. 40d box nails shall be permitted to be substituted for 16d common nails.

b. Nailing requirements shall be permitted to be reduced 25 percent if nails are clinched.

c. Heel joint connections are not required when the ridge is supported by a load-bearing wall, header or ridge beam.

d. When intermediate support of the rafter is provided by vertical struts or purlins to a load bearing wall, the tabulated heel joint connection requirements shall be permitted to be reduced proportionally to the reduction in span.

e. Equivalent nailing patterns are required for ceiling joist toceiling joist lap splices.

f. When rafter ties are substituted for ceiling joists, the heel joint connection requirement shall be taken as the tabulated heel joint connection requirement for two-thirds of the actual rafter-slope.

105

Table R802.5.1.9 Footnotes

g. Tabulated heel joint connection requirements assume that ceiling joists or rafter ties are located at the bottom of the attic space. When ceiling joists or rafter ties are located higher in the attic, heel joint connection requirements shall be increased by the following factors:

where:Hc = Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls.HR = Height of roof ridge measured vertically above the top of the rafter support walls.

106

R802.3.1 Ceiling joist and rafter connections

Ceiling joists shall be continuous or securely joined in accordance with Table R802.5.1(9) where they meet over interior partitions and are nailed to adjacent rafters to provide a continuous tie across the building when such joists are parallel to the rafters

107

R802.3.1 Ceiling joist and rafter connections

Ceiling joists shall be continuous or securely joined in accordance with Table R802.5.1(9) where they meet over interior partitions and are nailed to adjacent rafters to provide a continuous tie across the building when such joists are parallel to the rafters

108

R802.3.1 Ceiling joist and rafter connections (continued)

Where ceiling joists are not connected to the rafters at the top wall plate, joists connected higher in the attic shall be installed as rafter ties, or rafter ties shall be installed to provide a continuous tie.

109

R802.3.1 Ceiling joist and rafter connections (continued)

Where ceiling joists are not parallel to rafters, rafter ties shall be installed. Rafter ties shall be a minimum of 2-inch by 4-inch (nominal), installed in accordance with the connection requirements in Table R802.5.1(9), or connections of equivalent capacities shall be provided.

110

What s the issue here?

111

Continuous tie examples

Rafter ties used to be spaced not more than 4 feet o.c.

NOW, have to space at 24 so you can meet fastening of Table 802.5.1.9

112

Rafter Tie

Lookout nailed to rafter

Strap connects lookout to joists

Subflooring connects joists across floor

113

1x4 Crosstie Location1x4 Crosstie Location

Have to adjust span based on height of joist or tie (see Span Tables)

2x4

2x42x4

114

Adjust rafter span for height of tie

The tabulated rafter spans assume that ceiling joists are located at the bottom of the attic space or that some other method of resisting the outward push of the rafters on the bearing walls, such as rafter ties, is provided at that location. When ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the factors given below:

where:HC = Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls.HR = Height of roof ridge measured vertically above the top of the rafter support walls.

115

R802.3.1 Ceiling joist and rafter connections (continued)

Where ceiling joists or rafter ties are not provided, the ridge formed by these rafters shall be supported by a wall or girder designed in accordance with accepted engineering practice.

Ridge beam must be supported

116

Lateral

Continuous Load Path

117

Shearwall Overturning Restraint

118

Simpson Strongwall Shearwall

Steel Strong-Wall

Widths Available from 12 to 24

Plate Heights from 8 to 13

Stackable up to 20 plate height

Ordinary Moment Frame

Column Widths 6 to 15

Plate Heights from 8 to 19

Clear openings 8 to 16

119

QUESTIONS?