EWPAA Structural Plywood and LVL Design Manual - Engineered ...

nnaa=nnr42=5= 9 rowsThe assumed value of 0.9 for k 17 is satisfactory since it applies for up to 10 rows.Figure 13.7 shows the connection with the nailing pattern chosen.FIGURE 13.7: LVL / Plywood spliced joint13.8 Design of Screwed ConnectionsWood screws behave similarly to nails, the main difference being in withdrawal. The interlocking of woodfibre between the threads results in screws having higher withdrawal resistances than plane shanked nailswhose capacities are given in Table 4.2 of AS 1720.1-1997.Characteristic capacities for single screws are given in Tables 4.5(A) and (B), 4.6(A) and (B) and 4.7 of AS1720.1-1997 for the various loading conditions and whether the timber is unseasoned or seasoned.These values are based on the shank diameter and not the diameter at the root of the thread which wouldresult in a decided decrease in section modulus. In certain applications this may need to be taken intoconsideration.The previously mentioned characteristic capacities also apply to Type 17 self-drilling steel wood screwsmanufactured to AS 3566.The spacing of screws conforms to the provisions given for nails driven into pre-bored holes.13.9 Screwed Connector Design – MethodologyThe design process regarding screw connection design follows the same steps outlined in Section 13.4.199