|
|
|
|
|
Important Note – These are descriptions to changes implemented in version 10 and may not reflect current program behaviour.
For shear design, the program checked biaxial design for oblique members using the same formula as for non-rotated members, but a rigorous analysis considers the rotated shape of the member relative to the load.
The program now checks the shear stress against capacity in the x- and y- axis directions independently.
The actual critical shear stress occurs in another plane, and not necessarily perpendicular to the load, but due to the complexity of the calculations and the unlikeliness of shear design governing for oblique members, the program does not attempt to determine the critical shear plane. Instead it issues a design note cautioning you that the maximum shear is not one of the shear components shown.
Sizer did not do separate shear design for the x-axis and y-axis direction for glulam even though shear resistance is different in these directions. The program treated the member as if it was an isotropic member like sawn lumber, and designed using the glulam x-axis strengths without regard to the rotation of the member.
This was true even for members rotated 90 degrees, or columns loaded on the d-face, which are entirely loaded on the y-axis.
It has been corrected, and the program now treats the y-direction as a built-up system as per 7.5.3, using the technique described in Bug 3194 immediately above.
The program did not take into account the different b and d values for weak axis design in the equation for slenderness factor for RB = (d / b^2) ^ 0.5. For materials other than glulam, it applies the slenderness factor calculated for the strong axis to the weak axis. For glulam, it applied a factor of 1.0 to the weak axis without checking if a calculated factor is needed.
This applies to both oblique angle beams and columns loaded on the d face.
The program was applying the system factor KH and lateral stability factor KL calculated for the x-axis bending moment Mrx to the y-axis Mry. This has been corrected. Note that the KH factor differs for the y-axis because glulam beams are designed as built-up sawn members on the y-axis as per 7.5.3.
Another consequence of this problem was that KH was being reported as 0.00, but it was actually incorrectly using the Mrx value.
For a glulam beam loaded on an oblique angle, the modulus of elasticity Esy in the additional data section of the design results and the stiffness Eiy in the calculations section are based on the E of the glulam member, but should be based on the E of a No.2 D.Fir-L. Design for glulam members loaded on the weak axis considers the member as a multi-ply sawn member according to O86 14 7.5.3.
This is a display issue only and the values used to determine deflections are correct.
The specified notch shear force resistance ff in O86 7.5.7.4.2 for glulam design at tension notches has a lower limit of 0.9 MPa, which was not being implemented by Sizer. As a result, the program could significantly underestimate shear strength at tension side notches. This has been corrected.
If you entered a top-edge notch that is shorter than the distance from the outer edge of the support to the support point based on required bearing, the program could misidentify a compression notch as tension and vice-versa, as it does not have the loads analysis information outside the design span. This problem is restricted to the rare case that a notch on the upper face is loaded in tension, unless zero is entered as the unsupported length for compression notches.
A simple workaround to the most common instance of this problem is to simply not enter a short notch on the compression face, as there are no design implications of such a notch. The problem has been corrected nonetheless.
For glulam compression notch design, the program was sometimes selecting the equation in O86 7.5.7.3 (b) for unsupported notch length ec < member length d, when it should be selecting 7.5.7.3 (b) for ec > d. This has been corrected.
For weak axis design, the factor of .88 for bending moment strength fb from O86 Table 6.3.1C for beam and stringer sizes loaded on the wide face for Select Structural species was also being applied to No 1. And No 2., when 0.77 should have been applied. This has been corrected.
The factor of .77 or .88 from O86 Table 6.3.1C for beam and stringer sizes loaded on the wide face was applied to the size factor KZ instead of directly to the specified bending strength fb. This only affected the values of fb and KZ displayed, and had no effect on design.
Starting with version 8.2, the calculation of the shear value Cv in O86 7.5.7.5 did not consider the start and end of partial loads as "abrupt changes" for which to construct segments in the calculation procedure. This results in conservative Cv factors; in the extreme case of just one narrow partial load, a Cv close to that for uniform loads (3.69), when it should be close to the factor for a point load (2.46)
Note that this affected only the method for calculating shear from 6.5.7.2.1 (a) for beams greater than 2.0 m in volume (which is optional for those less than 2.0 m, and not used for columns). It has been corrected.
Starting with version 9.3, the program crashes when designing a glulam beam with load sharing active. This has been corrected.
For beam design with automatic self-weight, long-term load duration factor KD from O86 5.3.2.3 is calculated incorrectly for moment design and bearing design. This is most evident for heavy members for which the self-weight is a significant proportion of the dead load, and for these members the error was in the range of 1-2%. This has been corrected.
The following changes have been made to design notes regarding SCL materials:
A note indicating that apparent modulus of elasticity is used, which incorporates the affect of shear deflection.
Notes about preliminary design and about size factors varying from one manufacturer to another have been removed, as they were made when the SCL files provided were not proprietary
In all notes, the word BEAMS: has been removed as SCL materials are now applied to all member types.
In note for the LP material, the sentence about dry service conditions, etc., has been removed, as this is stated elsewhere.
The note about service conditions, treatment, and notches is now formatted in point form, as it was intended and is in the original ASCII output report.
The note for built-up beams now mentions side loading, and the first word is capitalized.