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The following improvements have been made to the treatment of Component and Cladding loads and C&C design.
C&C Loads Per Wall Line (Feature 206)
Because different wall lines can have different reference heights h because they are on different blocks, but be on the same face of the building in terms of N, S, E, W directions, the program now assigns separate C&C loads to each wall line. If the wall line includes walls from more than one block, the highest C&C load from the blocks is used.
As a result, C&C loads are shown in plan view on each wall line with exterior walls. Previously only one C&C load was shown for each building face .
Windward Pressure (Feature 207)
Previously the program used the worst case of the outward (suction) C&C pressure for both sheathing strength and nail withdrawal design, although it is possible for the combination of windward external pressures and negative internal pressure to be greater than leeward internal pressures and positive internal pressure. This caused somewhat conservative design for nail withdrawal, which is applicable only when exterior forces are outward.
Furthermore, some users were confused by the discrepancy between their calculations for windward pressures and the C&C pressures on the screen for a windward load direction shown.
Accordingly, shearwalls now calculates the windward and leeward pressures separately and uses the leeward for nail withdrawal design.
Plan View
Shearwalls now shows both the windward pressure if the displayed wind direction is directed towards a surface, e.g. for the west face for west to east loads. It previously showed the leeward (suction) pressure.
Elevation View
Both the leeward and windward pressures are now shown in elevation view.
Design
The worst of leeward and windward pressures are used for sheathing design. Only leeward pressures are used for nail withdrawal.
Reference Height for Ce (Bug 2500)
The reference height used for calculation of windward velocity pressure coefficient Ce is now the actual height at the top the level in question, rather than the eave height of the structure. This applies to both external and internal pressures. As the Ce factor at the 20m level is 0.82, and the minimum Ce is .70, the C&C loads can be conservative by as much as 17% on the lower levels, however, since the C&C load on lower levels does not tend to govern because of the accumulated shear forces on lower levels, this change has little effect for most designs.