D4.D.5 Member Resistance
The member resistances are calculated in STAAD according to the procedures outlined in section 5 (for sawn lumber) and 6 (for Glulam) of CSA08601.
These depend on several adjustment factors as follows:
 KD
 Load duration factor (Clause 4.3.2.2CSA08601, Table 4.3.2.2)
 KH
 System factor (Clause 5.4.4 and 6.4.3 and Table 5.4.4 CSA08601)
 K_T
 Treatment factor (Clause 5.4.3 and 6.4.4 CSA08601)
 KSB
 Service condition factor applicable to Bending at extreme fibre (Table 5.4.2 and 6.4.2 CSA08601)
 KSV
 Service condition factor applicable to longitudinal shear (Table 5.4.2 and 6.4.2 CSA08601)
 KSC
 Service condition factor applicable to Compression parallel to the grain (Table 5.4.2 and 6.4.2 CSA08601)
 K_SCP
 Service condition factor applicable to Compression perpendicular to the grain (Table 5.4.2 and 6.4.2 CSA08601)
 KSE
 Service condition factor applicable to modulus of elasticity (Table 5.4.2 and 6.4.2 CSA08601)
 KST
 Service condition factor applicable to tension parallel to the grain (Table 5.4.2 and 6.4.2 CSA08601)
 KZB
 Size factor applicable to bending (Clause 5.4.5 and Table 5.4.5 CSA08601)
 KZV
 size factor applicable to shear(Clause 5.4.5 and Table 5.4.5 CSA08601)
 KZT
 size factor applicable to tension parallel to grain (Clause 5.4.5 and Table 5.4.5 CSA08601)
 KZCP
 size factor applicable to compression perpendicular to grain (Clause 5.4.5 and Table 5.4.5 CSA08601)
 K_ZC
 size factor applicable to compression parallel to grain (Clause 5.4.5 and Table 5.4.5 CSA08601)
 CHIX
 Curvature factor (Clause 6.5.6.5.2CSA08601)
 CV
 shear load coefficient (Table 6.5.7.4A CSA08601)
 KN
 Notch factor(Clause 5.5.5.4CSA08601)
All of these factors must be specified as input according to the classification of timber and stress grade.
Explained here is the procedure adopted in STAAD for calculating the member resistances.
D4.D.5.1 Axial Tension

For Sawn timber
The criterion governing the capacity of tension members is based on one limit state. The limit state involves fracture at the section with the minimum effective net area. The net section area may be specified by the user through the use of the parameter NSF (see Table 3B.1). STAAD calculates the tension capacity of a member based on this limit state per Clause 5.5.9 of CSA08601.

For Glulam timber
The design of glulam tension members differs from sawn timber since CSA 08601 assigns different specified strength for gross and net section. The specified strength at net section is slightly higher than the strength of the gross section. Therefore, Glulam tension members are designed based on two limit states. The first one is the limit state of yielding in the gross section. The second limit state involves fracture at the section with the minimum effective net area. The netsection area may be specified by the user through the use of the parameter NSF (see Table 3B.1). STAAD calculates the tension capacity of a member based on these two limits states per Clause.6.5.11 of CSA08601.
D4.D.5.2 Axial Compression
The compressive resistance of columns is determined based on Clause.5.5.6 and Clause.6.5.8.4 of CSA08601. The equations presented in this section of the code assume that the compressive resistance is a function of the compressive strength of the gross section (Gross section Area times the Yield Strength) as well as the slenderness factor (Kc). The effective length for the calculation of compression resistance may be provided through the use of the parameters KX, KY, KZ, LX, LY and LZ (see Table 3B.1).
D4.D.5.3 Bending
The bending resistance of Sawn members are determined based on Clause 5.5.4 of CSA08601 and for glulam members are determined based on Clause 6.5.6.5 of CSA08601. The allowable stress in bending is multiplied by Lateral stability factor, KL to take in account whether lateral support is provided at points of bearing to prevent lateral displacement and rotation
D4.D.5.4 Axial compression and bending
The member strength for sections subjected to axial compression and uniaxial or biaxial bending is obtained through the use of interaction equations. Clause 5.5.10 and 6.5.12 of the code provides the equations for this purpose. If the summation of the left hand side of these equations exceeds 1.0 or the allowable value provided using the RATIO parameter (see Table 3B.1), the member is considered to have FAILed under the loading condition.
D4.D.5.5 Axial tension and bending
The member strength for sections subjected to axial tension and uniaxial or biaxial bending is obtained through the use of interaction equations. Clause 5.5.10 and 6.5.12 of the code provides the equations for this purpose. If the summation of the left hand side of these equations exceeds 1.0 or the allowable value provided using the RATIO parameter (see Table 3B.1), the member is considered to have FAILed under the loading condition.
D4.D.5.6 Shear
The shear resistance of the cross section is determined using the equations of Clause 5.5.5 and 6.5.7.2 of the code. Once this is obtained, the ratio of the shear force acting on the cross section to the shear resistance of the section is calculated. If any of the ratios (for both local Y & Z axes) exceed 1.0 or the allowable value provided using the RATIO parameter (see Table 3B.1), the section is considered to have failed under shear.