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The following changes apply to the implementation of the NBC Structural Commentary Figure I-15 method for “high-rise” structures, that Shearwalls uses on all structures for which the low-rise method is not permissible.
All-heights Pressure Coefficients Cp for H/D < 1 (Bug 2469)
The program now applies the wall pressure co-efficients Cp given in Figure I-15 when the height-to-depth ratio is less than 1.0. Previously it was using the maximum values, that is, those for H/D > 1 regardless of the dimensions of the building. This created conservative loading by as much as 33% for windward walls and 66% for leeward walls. The “D” used is the depth of the building block that the wall or roof panel was part of when the walls or roofs were originally created. The H used is the eave height for walls and the ridge height for roofs.
Refer to 5b) below, for the depth used for irregular structures.
Interior Zone Local C&C Coefficients (Bug 2480)
The program now implements the local coefficients +- 0.9 for component and cladding (C&C) loads on windward surfaces. These coefficients apply to sheathing and nailing design, as they are intended for components roughly the size of a window according to Commentary I-29. Previously the program was using the coefficient -1.0, from the 1995 NBC.
End Zone Local C&C Coefficient (Bug 2480)
The program now implements the local coefficients -1.2 for C&C loads on the end zones of windward surfaces. These coefficients apply to nailing design, as they are suction forces. Previously the program was not using separate end zone wind pressures for nail withdrawal, or showing them in the plan or elevation view.
CpCg Value for C&C Loads in Log File (Bug 2480)
The combined pressure and gust CpCg coefficient shown in the log file for all-heights C&C loads for the all-heights method did not correspond to the Cp coefficient multiplied by the Cg factor; instead included the Ce factor as well. This has been corrected.
Ce Value for C&C Loads in Log File (Bug 2480)
The exposure factor Ce in the log file for all-heights C&C loads was always shown as 1.0. The correct factor now appears.