In section 3, qualification testing and performance requirements are based on small sample sizes (n), and involve calculation of the sample mean ultimate load (p.50). To determine allowable load from mean values from qualification test data, the relationship is:
F = P.50 / X [A-2]
where X = gross adjustment factor relating allowable load (F) to population average ultimate load (P.50). Setting equations [A-1] and [A-2] equal:
P.05 / 2.1 = P.50 / X [A-3]
Using the relationship between population mean and population 5th percentile:
P.05 = P.50 (1 − 1.645 · COV) [A-4]
where 1.645 = the population one-sided tolerance limit for calculating 5th percentile assuming large sample size and normal distribution; COV = population coefficient of variation. Substituting [A-4] into [A-3]:
P.50 (1 − 1.645 · COV) / 2.1 = P.50 / X [A-5]
Solving for X:
X = 2.1 / (1 − 1.645 · COV) [A-6]
Because performance tests in section 3 are based on small sample sizes, equation [A-6] is modified to accept a one-sided tolerance limit for small sample sizes. The resulting gross adjustment factor equation is:
X = 2.1 / (1 − k.05,.75,n · COV) [A-7]
where k.05,.75 = 5th percentile at 75% confidence one-sided tolerance limit for sample size n (ASTM D2915, Table 3).
Substitution of sample mean ultimate load (p.50) and equation [A-7] into equation [A-2] results in equation [A-8]. Note that coefficient of variation for small sample sizes would be large, and would result in an overly-conservative calculated allowable property (F). For this reason, the population coefficient of variation (COV) remains in equation [A-4]. When using performance test results on smaller sample sizes:
F = p.5 / X [A-8]
Table A1-1 provides values needed for determining the adjustment factor X, for calculating allowable properties using section 3 performance test results. Determine the capacity as the mean test value divided by Gross Adjust Factor, and is applicable to a shallower rim board of the same thickness and species combination. Table A1-2 presents the minimum Allowable Stress Design Values for rim boards qualified to this standard.
Table A1-1. Adjustment factors and sample statistics for determining allowable properties from performance test results.
| Allowable Property | Gross Adjustment Factor, X | Sample size (n) | k.05,.75,n | Assumed Population COV | Adjustment factor, C |
|---|
| Vertical Uniform Load Transfer (V) (§3.2.1) | 3.0 | 10 | 2.104 | 0.14 | 2.1 |
|---|
| Lateral Load Transfer (H)1 (§3.2.2) | 2.8 | 10 | 2.104 | 0.12 | 3.0 |
|---|
| Concentrated Load Transfer (P) (§3.2.3) | 3.0 | 10 | 2.104 | 0.14 | 2.1 |
|---|
| Edgewise Bending (F) (§3.2.4) | 3.452 | 28 | 1.879 | 0.21 | 2.1 |
|---|
| ½" dia. Lag Screw Lateral Resistance3 (Z) (§3.3.1) | 4.0 | 10 | 2.104 | 0.12 | 3.0 |
|---|
1. H is a wood-framed system, however, assumed COV is for rim board product. Safety Factor is a calculated value that results in a gross adjustment factor of 3.0.
2. Note that the Gross Adjustment Factor (X) incorporates adjustment factors for volume (1.45), center-point loading (1.08), and moisture (1.05).
3. Capacities for the following items shall be determined according to ICC-ES AC 47, or the NDS, as applicable: connection of the top edge of the rim board to the building diaphragm; attaching the rim board to the wall plate below; attaching the rim board to the I-joists; attaching the exterior siding to the rim board; attaching an exterior deck ledger.
Table A1-2. Allowable stress design values for TECO rim board.
| Rim Board Grade | Minimum thickness (in) |
H1 (lb/ft) | V1 (lb/ft) | Z1 (lb) | P1 (lb) |
| d ≤ 24 | D ≤ 16 | 16 ≤ d ≤ 24 | D ≤ 24 | d ≤ 24 |
|---|
| Standard | 1 | 180 | 3,300 | 1,650 | 300 | 3,500 |
|---|
| 1⅛ | 180 | 4,400 | 3,000 | 350 | 3,500 |
| Performance | 1 | N/A2 |
|---|
| 1⅛ | 200 | 4,850 | 3,200 | 350 | 3,500 |
1. H is horizontal shear load transfer; V is bearing (vertical) load; Z is lateral resistance of ½-in. diameter lag screw; and P is concentrated vertical load capacity.
Appendix 2 — Alternative Test Method
Alternate method for Vertical Uniform Load Transfer Capacity
(A) Test Specimens
- Prepare test specimens in accordance with section 3.2.2 (A) except the sill plate is not required for the assembly. To avoid direct bearing on the I-joists, an end notch of approximately ½ inch (12.7 mm) in depth and at least 3-1/2 (89 mm) inches in length shall be provided on the flange (bottom side of assembly only).
(B) Test Method
- Apply loads through the sill plate while the sheathing reacts through full-width bearing, or vice versa. No lateral supports shall be used for the testing assembly.
- Record cross head position versus load, at least every 0.01 inches (0.3 mm).
- Load should be applied at a uniform rate and failure should occur within two (2) minutes.
- Apply preload of not more than 10% of anticipated maximum load. Load to failure. Record the load at failure and the load at displacement of 0.06 inches.
(C) Criteria
- Calculate the vertical uniform load transfer mean test value as the average recorded load of all ten (10) test specimens divided by the tested rim board length, or the average load at 0.06-inches displacement times 3 divided by the length of rim board, whichever is less, in [lbf/ft] units. The vertical uniform load transfer mean test value shall meet the criteria in Table 1.
Appendix 3 — Conversion of Allowable Stress Design Values to Limit States Design
When appropriate – and for all use in Canada – design of structures shall follow the principles of Limit States Design (LSD). It is acceptable to use a simple mathematical calculation to convert Allowable Stress Design (ASD) values to appropriate factored resistances for LSD applications.
The following sections explain the conversion of the ASD values from Table A1-2 and are harmonized with the requirements of the Canadian Construction Materials Center (CCMC), which issues proprietary evaluation reports for building products used in Canada.
1. Horizontal Load Capacities (H)
This conversion follows the same procedures used in clause 9 of CSA O86-01, where ASD values for shear walls were converted to factored resistances for LSD.
LSD: φKD,LSDHLSD,std term ≥ αQQ (A3-1)
ASD: HASD,short term ≥ Q (A3-2)
Conditions: φ = resistance factor = 0.7 for shear walls; KD,LSD = LSD load duration factor of 1.15 for LSD short-term loading; αQ = LSD load factor of 1.5 for wind; Q = Applied load. From Equations A3-1 and A3-2:
φ HLSD,std term = [αQ/KD,LSD] HASD,short term = [1.5/1.15] HASD,short term = 1.304 HASD,short term
The conversion factor for the factored horizontal load capacities (φHLSD) is 1.304 but it is based on LSD standard term, not short term load duration.
2. Uniform Vertical Load Capacities (V)
LSD: φKD,LSDVLSD ≥ αDQD + αLQL (A3-3)
ASD: KD,ASDVASD ≥ QD = QL (A3-4)
Conditions: φ = resistance factor = 0.95 for compression members; KD,LSD = LSD load duration factor of 1.0 for standard-term loading; αD = LSD dead load factor of 1.25; αL = LSD live load factor of 1.5; KD,ASD = ASD load duration factor of 1.15 for snow load on roof. When calibrated to QL/QD = γ = 4.0 as in accordance with CSA O86:
φVLSD = (1.25 + 4×1.5) / (1.0×(1+4)) × 1.15 × VASD = 1.668 VASD
Due to the location of rim boards within a wall assembly, it is not required to include adjustments for the effects of relative humidity – consistent with CSA O86 – so the adjustment factor for the factored uniform vertical load capacities is 1.668.
3. Concentrated Vertical Load Capacities (P)
The conversion factor for the factored concentrated vertical load capacities (φPLSD) is the same as for factored uniform vertical load capacities (φVLSD) and is 1.668.
4. Lag Screw Capacities (Z)
The derivation of the lag screw conversion factor follows the same procedures as for factored uniform vertical load capacities. The conversion factor for lag screw capacities (φZLSD) is also 1.668.
Table A3-1. Converted, factored resistances of TECO rim board.
| Rim Board Grade | Minimum thickness (mm) |
φH1 (kN/m) | φV1 (kN/m) | φZ1 (kN) | φP1 (kN) |
| d ≤ 610 | d ≤ 406 | 406 ≤ d ≤ 610 | D ≤ 610 | d ≤ 610 |
|---|
| Standard | 25 | 3.4 | 80.3 | 40.2 | 2.2 | 26.0 |
|---|
| 29 | 3.4 | 107.1 | 73.0 | 2.6 | 26.0 |
| Performance | 25 | N/A2 |
|---|
| 29 | 3.8 | 118.1 | 77.9 | 2.6 | 26.0 |
1. H is horizontal shear load transfer; V is bearing (vertical) load; Z is lateral resistance of ½-in. diameter lag screw; and P is concentrated vertical load capacity.
