Frame and Panel Dimensions

Two 1S1B and two 2S2B sheathed frames were tested. Dimensions of the 1S1B and 2S2B frames are described in Chapters 2 and 3, respectively.

The SIPs were of two nominal thicknesses: 4-inch and 6-inch. The 4-inch panel consisted of a 3.5 inch extruded polystyrene (EPS) core enclosed by 7/16 inch oriented strand board (OSB) skins to create a panel thickness of approximately 4.5 inches. The 6- inch panel had 5.5 inches of EPS core with 7/16” OSB skins to provide a total thickness of approximately 6.5 inches. The 4-inch panels were supplied by Great Lakes Insulspan of Blissfield, Michigan and the 6-inch panels were provided by Premier Building Systems of Fife, Washington. All panels were installed with screws that had a shank diameter of 0.190 inches. Screw length was 6 inches for the 4-inch panels and 8 inches for the 6-inch panels unless noted otherwise.

Two six-inch panels were attached to a 1S1B Douglas fir frame. The panels were oriented as shown in Figure 5-1. The panels were joined by a continuous 7/16” x 4” OSB spline attached to each OSB skin of the SIP with 8d nails 6 inches apart (nails had

clipped heads and were driven with a pneumatic nail gun). This frame is distinct from the frame described in Chapter 2 and will hereafter be labeled the “Sheathed 1S1B Douglas Fir Frame.”

Figure 5-1 Douglas Fir 1S1B Sheathed Frame

A continuous four-inch panel, 12’ wide by 8’ high, was applied to the 1S1B white oak frame, which was also tested in the unsheathed condition as described in Chapter 2.

The 2S2B Douglas fir frame was sheathed with four six-inch panels of size and orientation as shown in Figure 5-2. The panels were joined by a continuous 7/16” x 4” OSB spline attached to each OSB skin of the SIP with 8d nails 4 inches apart.

4' 8" 8' 0" 9' 0" S tro n g A x is (t y p .) 7/16" OSB Spline (both sides)

Figure 5-2 Douglas Fir 2S2B with SIPs

The 2S2B eastern white pine frame was sheathed with four, four-inch panels each of which was 12’ wide by 8’ high as shown in Figure 5-3. All panel joints were

coincident with frame members, and no splines were used. Both 2S2B frames were also loaded in the unsheathed condition as described in Chapter 3.

4' 8" 4' 0" 8' 0" 8' 0" 17' 0" St ro n g A x is 7/16" OSB Spline (both sides)

Figure 5-3 Eastern White Pine 2S2B with SIPs Strong Axis 12' 0" 12' 0" 8' 0" 8' 0 "

5.3.Experimental Program

The methods of loading and data collection are described in Chapters 2 and 3 for the 1S1B and 2S2B frames, respectively.

5.4.Overview of Test Results

A description of the load cycles for all frames is provided in Appendix B for the 1S1B frame and Appendix G for the 2S2B frames. A brief summary of the load cycles and attachment methods for each of the sheathed frames is given in the following sections.

5.4.1. 1S1B Sheathed Douglas Fir

The sheathed 1S1B Douglas fir frame is distinct from the unsheathed 1S1B Douglas fir frame as described in Chapter 2. The sheathed 1S1B Douglas fir frame was load cycled four times with SIPs installed followed by two cycles without sheathing. The first two load cycles were conducted with screws 12 inches apart and the final two were conducted with screws 8 inches apart.

Inspection of the frame upon disassembly along with analysis of the results indicated significant joint damage occurred during the cycles with SIPs installed. Therefore, this frame is not included in the discussion of unsheathed frames nor will its results be compared to any results for the unsheathed condition.

5.4.2. 1S1B White Oak

The unsheathed 1S1B white oak frame was initially cycled 3 times prior to installation of SIPs. SIPs were installed for cycles 4 through 10. As mentioned previously, the intent was for the load path to be from timber frame into the sheathing and back out via the timber frame reaction points. Unfortunately, due to interference caused by the reaction fixtures, the load path was disrupted for cycles 4 through 8; therefore, discussion of results will be limited to cycles 9 and 10.

The panel was attached with 6-inch screws located at 16 inches on center. Screw holes (1/8 inch diameter) were predrilled through the panel and into the timber to

screws, and a 0.5-inch plywood shim was installed between the frame and panel resulting in a screw penetration of 1 inch into the frame timbers.

5.4.3. 2S2B Douglas Fir

The 2S2B Douglas fir frame was subjected to 115 load cycles. The first three and the last three load cycles were conducted in the unsheathed condition. The intermediate 99 load cycles were conducted with 6-inch SIPs installed. Load cycles 4 through 58 were conducted with screws installed 12 inches apart and cycles 59 through 112 were

conducted with screws 24 inches apart. Cycles 8 through 57 and 61 through 110

subjected the frame to 0.5 inches of displacement in each direction at a rate of 1 cycle per second.

The cross-sectional width of the beams was less than that of the columns. In order to provide a flush surface for installation of SIPs, shims were installed along the entire length of all beams. A double layer of 7/16-inch OSB shims provided a total shim depth of 0.875 inches. Given the screw length of 8 inches, panel thickness of 6.5 inches and a shim thickness of 0.875 inches, the screws penetration into the beams was only 0.625 inches.

5.4.4. 2S2B Eastern White Pine

The 2S2B eastern white pine frame was subjected to 118 load cycles. The first three and the last two load cycles were conducted in the unsheathed condition. Load cycles 1 through 5 were conducted without a sill timber and then a sill was installed for the remaining cycle. The sill facilitated full perimeter attachment of the SIPs. All tests were conducted with 6-inch screws located 12 inches apart.

Openings were cut in the panels for load cycles 11 through 116. The openings simulated window or door openings and these tests were conducted as a preliminary investigation for future research.

Load cycles 15 through 114 subjected the frame to 0.5 inches of displacement in each direction at a rate of 1 cycle per second, and no data was recorded for these cycles.

5.5.Results