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Important Note – These are descriptions to changes implemented in version 9.3 and may not reflect current program behaviour.
The program now implements the new CSA O86-14 Engineering Design in Wood Standard. As the National Building Code referencing CSA O86-14 is not yet released, and provincial building codes have not yet mandated the use of O86-14, the program also allows you to continue using CSA O86-09.
A drop list box called Design Code has been added to the Design settings, with the choices
CSA O86-09/ NBC 2010
CSA O86-14/ NBC 2010
This input form has been reorganized to group everything that can change based on the selection of design code edition in one box. Thus what was previously in the Modification Factors group has been moved into an expanded Design Code Options group.
At the head of the Force vs. Resistance table, it now says …using CSA O86-09 or …using CSA O86-14, as the case may be.
It shows the edition of the O86 currently being used, and the fact that it is the May 2014 printing of the CSA O86-14, in the About Sizer box accessed from the Help menu and in the Building Codes box accessed from Welcome Box. In the main body of the Welcome box, it indicates that either of these codes can be used.
The references to the CSA 086 design code clause numbers in the input forms and screen messages, and in warnings, design notes and other program output, have been updated to show the 2014 edition clause numbers when CSA O86-14/ NBC 2010 is chosen as the design setting. It continues to show 2009 edition numbers when CSA O86-09/ NBC 2010 is chosen.
The notes and messages were changed to consistently not include "CSA", always include "O86", and not include the edition year ("-09" or "-14"). The details about the design code being used are shown prominently elsewhere in the input and are not needed with every note and message.
In the course of this work minor syntactical corrections were made to a few notes and messages.
The on-line Help in the new Web Help format has been updated to refer to the CSA O86-14 design code clauses. The older Help format is also included in the installation to allow you to use Help that references O86-09.
For Design Office installations of Sizer, the on-line 2014 edition of CSA O86 in .pdf form has been made available. Refer to the Design Office Read me file for details. This feature is not available to Stand-alone Sizer users.
The remainder of the changes described in this section occur when CSA O86-14 is selected as the design code edition in the Design Settings.
The following changes have been made to the load combinations used in the program due to changes in O86-14 5.2.4.1 as compared to O86-14 4.2.4.1. These changes apply to ultimate limit states only; serviceability load combinations have not changed.
The changes can be seen where load combinations are shown in the Load Combinations dropdown in the Analysis diagram screen, in the Critical Load Combinations section of the Additional Data in the Design Check output, and in the Analysis Results output.
For load combinations 2) and 3), the companion load factor for live and snow loads, when these loads are combined with each other but without wind or earthquake, has changed from 0.5 to 1.0.
Note that this is done for snow loads when sustained live loads are also combined with the live load, or when they constitute the principal live load.
It is done for both uplift (0.9D) and gravity (1.4D) combinations.
The companion load for live loads due to storage for load combinations 3 and 4 has changed to be 0.5 more than the usual live load companion factor. The effect of this is to have increased this factor from 1.0 to 1.5 for load combination 3. For load combination 4, it remains at 1.0. So for principal snow loads combined with storage, equipment loads, the sustained live load factor is now 1.5 rather than 1.0.
Because the sustained live companion factor is now different for load combinations 3 and 4, the Sustained live loads due to… input now shows 1.0 or 1.5 as the companion factor, rather than just 1.0.
The program now implements the expression for size factor Kbg from O86-14 7.6.7.5.1 in place of the one in 6.5.6.5.1 O86-09. This expression depends on the beam depth, as well as the width of the widest lamination and the distance between zero moment points that also went into the previous formulation. The form of the equation is very different and it is limited by 1.3 rather than 1.0, however since 7.6.7.5.1 says to take the smallest of the resistances derived from including the lateral stability factor or the Kzbg factor, Kzbg values from 1.0 to 1.3 never govern.
The program evaluates Kzbg independently for each span, and makes a separate determination of moment resistance vs. the maximum moment in each span using the Kzbg factor computed for that span.. Although this complies with a note regarding multiple "points of inflection" that has been added to O86 for the 2014 edition, Sizer has always implemented moment design in this way.
(We believe that "point of inflection" in this Note is intended to mean zero-moment point, or point of counterflexure, rather than the meaning of the term in the mathematical sense.)
The program implements the changes to glulam shear resistance calculations from O86-14 7.5.7 as compared to O86-09 6.5.7. Some of the changes involve only nomenclature, the form of the equations used, and a re-organization of the design code clauses, rather than substantive changes to the design calculations. The program input and output have been changed to reflect the new nomenclature, and wherever necessary design calculations have been updated, as described below.
In what follows, what were formerly O86-09 6.5.7.1 (a) and (b), and are now O86-14 7.5.7.2 (a) and (b), will be referred to as Case (a) and Case (b) respectively.
For beams that are notched, the notch factor has been removed from Case (a), so that for beams for which that case is used, a notch factor is no longer applied.
Note that Case (b) no longer explicitly contains a notch factor, but the expressions for the notch factor from 6.5.7.2.2 have been incorporated into the equations for shear resistance at notch locations from 7.5.7.3 and 7.5.7.4 for compression-side and tension-side notches respectively
The expressions in O86-14 7.5.7.3 for shear resistance at compression side notches are identical to Case (b) equation from O86-09 with the notch factor from 6.5.7.2.2 included. However, the reorganization of these provisions changed the requirements as to application of Case (a) vs. Case (b) as follows:
For O86-09, if the beam was greater than 2 m3 in volume or if you chose in the Design Settings to use Case (a) instead of Case (b), at a support notched at the compression edge the program would use only Case (a), which for -09 included a notch factor.
For O86-14, the program must use the notch-specific expressions from 7.5.7.3, which are the equivalent of the O86-09 Case (b) with the notch factor KN. Thus the program must run through the Case (b) analysis at notch locations when previously it didn’t.
Note that even when each support is notched, Case (a) is still evaluated because there are non-notched locations on the beam, and Case (a) is independent of the location of the maximum shear force on the beam.
For compression-side notches, if you select in the Design Settings to use Case (b) only if it provides and advantage over Case (a), the program uses the notch-specific expressions in O86-14 7.5.7.3 even if they do not provide an advantage over Case (a). For O86-09 the program does not use Case (b), which is equivalent to the equations in O86-14 7.5.7.3, unless they provide an advantage, that is, the design ratio for Case (b) is less than that for Case (a).
Note that for O86-14 tension-side notches and non-notched locations, the program behaves as the CSA O86-09 option does; it chooses the most advantageous of Case (a) and Case (b) rather than the worst of these cases.
If you specify that Case (b) is to be used, then uses the notch-specific equations at notch locations and Case (b) analysis only at other locations. This is equivalent to the behaviour for O86-09.
The shear resistance for notches which extend less than a the beam depth d from the inside face of the support will now be analysed as if there was no notch, as per O86 7.5.7.4.1. Case (a) and Case (b) analysis is applied without reduction in net section area or application of a notch factor.
For notches which extend greater than a distance d from the inside face of the support are analysed using Case (a) and Case (b) analysis, for each of them using the net area of the member with notch material removed as per O86 5.3.8.1. This is equivalent to using a factor 1 – dn/d rather than (1 – dn/d )2 used for O86-09, so the effect is a greater reduction in shear strength than previously.
Although O86 7.5.7.4.1 does not explicitly address notches which extend greater than d WoodWorks has been informed by the Canadian Wood Council that the use of O86 7.5.7.2 with net area is intended, and that a clarification stating so will be published in a future revision to the CSA O86.
Since O86 7.5.7.4.1 refers to 7.5.7.2, the Design Settings regarding use of Case (a) vs. Case (b) are respected; in particular you can select whether to use the most advantageous of Case (a) and Case (b). This does not represent a change from O86 09, but it is now different than for compression notches. For compression notches, the worst case of Case (a) and the notch-specific equations that are equivalent to O86-09 Case (b) is always used.
In the line of the CALCULATIONS section of the Additional Data which indicates whether Case (a) or Case (b) was used, if longitudinal shear for a tension-side notch governed, the words via 7.5.7.4.1 are added, followed by either using gross area An or using net area Ag according to whether the notch extends more than a distance d from the support.
The program now implements the new provision from 7.5.7.4.2 for fracture shear resistance Fr at tension-edge notch locations. It calculates both Fr and longitudinal shear Vr, as described above, and uses the most critical case for design of the beam. Fr is compared with the local maximum shear, not the shear-at-distance d, as per O86 7.5.7.4.1.
The section area A used is the gross area Ag, not the net area
The calculation of KN in 7.5.7.4.2 is identical to the one used for tension side sawn lumber notches from O86-14 6.5.5.3, except that the widest lamination width is beff is used in place of b.
The lamination width used for b eff is the one input in Beam view, which was previously used to calculate the Kzbg factor (O86-14 7.6.7.5.1).
Note that checkbox indicating that beam width be used is active only for unknown section size. This is because there are glulam beams manufactured such that you do not know what sizes of lamination widths have been used. The beam use of the beam width in this case is conservative for KN for this as it is for Kzbg
The label for this checkbox has been modified to indicate that it applies to both Kzbg and notch Ff value.
Note that a service factor KStp is defined for this purpose, and it is different than the usual service factor for longitudinal shear Ksv, that is used for all other shear design checks. It is 0.85 instead of 0.87 for wet service conditions and appears in the FACTORS table of the Additional Data output.
If there is a tension-side notch at the critical location on the beam for shear design, a new line in the Force vs Resistance Table shows Fr, Vf, and the ratio between them. A line has been added to the FACTORS table starting with the symbol Ff showing factors for KH, KD, KT, ,KStp and KN..
If a fracture shear resistance governs at a tension notch, the line in the CALCULATIONS section saying which of Case (a) and Case (b) governs is not shown. Case (a) and Case (b) are still output in the Analysis vs. Design table, with both design ratios shown. (This is in contrast to the situation whereby Case (a) or Case (b) governs, when only the ratio for the case used is shown)
In the Analysis vs. Design Table, where it used to say Shear (a) and Shear (b), it now gives the exact design code clause reference. For no notches or for tension side notches, it shows Shear 7.5.7.2a and/or Shear 7.5.7.2b. Whether it shows 7.5.7.2a and 7.5.7.2b or just one of them depends on the choice in the Design Setting regarding Case (a) vs. Case b analysis.
Tension notches also show a line for fracture shear starting with Shear 7.5.7.4.2 . Tension notches also indicate in the CALCULATIONS section that 7.5.7.2a or Shear 7.5.7.2b are via 7.5.7.4.1.
For compression side notches, the table shows Shear 7.5.7.2a and/or Shear 7.5.7.3a or Shear 7.5.7.3b, depending on which of the latter two apply. Whether Shear 7.5.7.2a is shown depends on the Design Setting regarding Case (a) vs. Case (b) analysis.
In the Analysis vs. Design table, the notation Vr from O86-09 6.5.7.2.1(a) has been changed to Wr from O86-14 7.5.7.2a.
The KN factor has been removed from the Additional Data table, and replaced with a dash ( – ) for all cases except the new fracture shear check at tension notches from O86 7.5.7.4.2, described above. For Case (a) analysis, the calculation of KN has been removed; for Case (b) and all other notch-specific cases, what was formerly KN has been incorporated into the equation for shear resistance Vr.
The symbol e representing unsupported length for compression side notches has been changed to ec in the CALCULATIONS section of the Additional Data section, in conformance with a change of notation from O86-09 6.5.7.2.2(b) to O86-14 7.5.7.3.
Because I-joist bearing design procedures are highly proprietary and included in customized versions of Sizer, the program does not implement the new Reaction Resistance provision from O86-14 15.2.3.5. A line has been added to the Reactions and Bearing table indicating that reaction resistance is not considered.