RISAConnection can perform code checks according to the Canadian (CSA S16-2009 or CSA S16-2014) steel codes. This is offered only for the following connections:
There is a difference in philosophy between the US and Canadian steel design codes. The AISC provisions seek to identify all possible failure modes. The CISC manual and CSA specification, on the other hand, try to limit the number of failure modes which need to be investigated by the engineer. They do this by ignoring failure modes which are not believed to control, or by combining multiple failure modes into a single simplified calculation.
The connection design procedures used in RISAConnection are based on the AISC design procedures, but modified to fit the CSA S16 code provisions. AISC formulas and phi factors have been replaced by CSA formulas and phi factors in most cases. Therefore, the program will generally try to check all possible failure modes, even when they are not likely to control. This means that some failure modes are calculated in circumstances when the CSA code says they do not need to be checked.
In some cases, there is not a direct CSA/CISC counterpart to an AISC equation. In those cases, some engineering judgment is required. RISA engineers have chosen to look for the CSA code provisions that are most similar to the AISC code provisions and use them. In some cases this may mean the code equations cited by RISAConnection come from a clause (like the seismic chapter) which CSA does not expressly require to be checked.
There are also instances where the CSA code requires a failure mode to be investigated but does not give any direct guidance on how to do so. In these cases, the equations used for the AISC checks will also be used for the Canadian code. The only differences would be the use of Canadian phi factors.
One significant difference between the AISC and CSA code provisions related to how the code accounts for fillet welds where the orientation of the weld segments vary. The Canadian code reduces the strength of some weld segments by the value Mw which can be as much as a 15% reduction. RISAConnection does not fully account for this reduction at this time. Instead, the program identifies cases where some weld segment will have a Mw value of less than 1 and conservatively reduces all weld segments in those connections by 15%.
The result of these changes is that the RISAConnection results will not directly match the CISC capacity tables for welds.
The ICR method of weld capacity calculations was done for E70xx welds. Extrapolating these values to higher strength welds introduces some uncertainty into the weld capacities. AISC uses an additional 10% strength reduction for weld strengths above 80 ksi and less than 200 ksi, as well as a 15% reduction for weld strength above 100 ksi. RISAConnection reduces Canadian weld strengths using the same approximate criteria.
The design procedure used for End Plate Moment connections comes primarily from AISC Design Guides #4 and #16.
Note:
The AISC manual has specific checks to ensure that shear connections are flexible enough to accommodate the end rotations of simple beams. These rotational ductility checks are given in the manual, based on the requirements of section J1.2. The CSA provisions have similar requirements in Clause 21.2, but the manual does not give specific guidance on how to address these requirements. For this reason, the procedure used for AISC connections will also be used when code checking to the CSA provisions. These requirement may be turned off by unchecking the box on the solution tab of the global parameters.
The CSA manual does not directly address the stability issues of extended shear tabs where the torsional flexibility of the plate can be insufficient to insure the lateral stability of the connection. In these cases, a stabilizer plate may be required per equation 10-6 of the AISC 14th edition.
Since this issue is not directly addressed by the CSA manual, this is checked using the AISC formulas directly. More information on RISAConnections implementation of these provisions is given in the Stability and Geometry Checks topic.
The current version of the Canadian steel manual only gives the Instantaneous Center of Rotation (ICR) method for dealing with weld or bolt groups loaded eccentrically. However, the elastic method is still valid and conservative. Therefore, it is included as an option in the RISAConnection program. Furthermore, the elastic method is required for some weld groups where the ICR method is not fully defined. See the Weld Checks topic for more details.
The elastic procedures are based on the AISC steel manual procedures which are based off of the method described by Blodgett.
Clause 14.8.1 requires that the effects of Copes be accounted for in the design of the member. However, the CSA specification and CISC manual do not give direct guidance on how to account for these effects. Instead, page 3-63 suggests using the provisions of the AISC manual. Therefore, coped beam failure calculations will directly reference the relevant AISC equations.
When using an imperial designation for the bolt material (A325, A490), RISAConnection uses the strength of the bolt from the ASTM, not the "soft conversion" values given in the CISC manual for table 3-3.
The code checks for bolt bearing in the Canadian code do NOT have the option for reducing the capacity of the connection in cases where limiting the deformation of the bolt hole is desired.
RISAConnection does not use the procedure described in the CISC manual on page 3-36. That procedure is described as an easy to use and conservative procedure. Instead, RISA uses the procedure described in the Eccentricities topic. This procedure is more complicated, but should be more accurate and less conservative.
The assumed size for bolt holes is based on clause 22.3.5.2 of the CSA specification and Table 3-48 of the CISC manual. Slotted bolt holes are based on the Miscellaneous Fastener Detailing Data on page 6-166.
Note:
Slip Critical Bolts are not currently checked for the Canadian code.
The assumed dimensions of Weld Access Holes for direct weld moment connections are based on figure 5.1 of CSA W59-2003. The program always assumes the beam is a rolled shape.
Clause 27.2.4 of the CSA provisions give regarding the strength of a columns panel zone in a seismic moment connection. Checking this strength is not explicitly required for other types of loading. However, to be consistent with parallel AISC provisions, RISAConnection will always run the panel zone shear check, regardless of the applied load.
The higher Panel Zone capacity due to increased the detailing requirements of 27.2.4.3 are NOT assumed in the RISAConnection calculations. The capacity of the panel zone is NOT reduced based on the presence of axial load as it would be if the AISC provisions were selected.
Clause 21.3 appears to assume that the capacity of the web will be based on clause 13.4.2 (shear strength for Plastic Analysis). RISAConnection uses the panel zone capacity from 27.2.4 (as described above) to determine the shear demand on the web doubler plate.
The AISC design guide on column strengthening / stiffening recommends a maximum b/t ratio for the doubler plates to prevent local bucking of the doubler plate under applied shear stress. For the Canadian code, RISAConnection uses an h/t ratio of 1014/sqrt(Fy) for this maximum ratio. This is based on the h/t limits given in clause 13.4.1.1. Note: this max ratio must be calculated using MPa for the units of the yield stress.
Clause 21.3 (a) and (b) give equations for the yielding or buckling of the column web. These provisions assume that web buckling can only occur for class 3 or class 4 webs. RISAConnection will always check the web for BOTH failure modes regardless of the web classification.
For Bolted end plate connections, the formula for web yielding is taken as (12*tfc+2*tp+tfb)*Fy*twc. This increase accounts for the larger spread of force allowed by the presence of the end plate.
For Bolted end plate connections, the formula for web buckling is taken as 640,000*twc*(12*tfc+2*tp+tfb)/(h/twc)2. This increase accounts for the larger spread of force allowed by the presence of the end plate.
RISAConnection uses the method described in the commentary to clause 21.3 to reduce the Web Yielding and Buckling capacities when the connection is located close to the end of the column. This involves using a bearing distant of (N + 4t) instead of (N+10t).
Clause 21.3 (a) does not directly address the situation where the concentrated force occurs close the top of the column. For this case, RISAConnection uses the AISC method of reducing the capacity by 50% whenever the connection is within 10*tfc of the end of the column.
Clause 14.3.2(a)(ii) for web crippling applies specifically to the bearing resistance of a beam. This is analogous to concentrated loads applied to columns, but is not directly mentioned in the connection section of the CSA code. Since this is described as a web crippling capacity calculation, RISAConnection uses it wherever AISC connections are checked for web crippling.
For the r value calculation, RISAConnection is conservatively ignoring the presence of the column web. Rather than including the 25tw web strip discussed in clause 14.4.2.
HSS members are available for design per the CSA S16 design codes for the following connections: Shear Tab, Clip Angle (One Side), Direct Weld Moment, Flange Plate Moment, HSS to HSS, Vertical Diagonal Brace, Chevron Brace, and Knee Brace. The HSS section checks are all referenced per the CIDECT Design Guide 3 (2nd Edition) for Rectangular Hollow Section (RHS) members and the CIDECT Design Guide 1 (2nd Edition) for Circular Hollow Section (CHS) members. The majority of HSS checks come from CIDECT Design Guide Tables 4.1 and 7.1. The applicability of this table depends on the "Range of Validity" at the end of the table. This means that if a connection falls outside these limits then the procedures given by this table may not be sufficient to guarantee a safe connection. It does not necessarily mean that the given code checks are invalid. It may mean that the parameters of the connection fall outside the limits of existing test data or that other limit states not listed could control. These parameters are checked as part of the HSS Limitations limit state, which includes checks for:
These limit states are very similar to those used in the AISC Chapter K checks. See the HSS Checks section for more details about which limit states are checked.
Per CIDECT Clause 1.2.1, the resistance should be multiplied by 0.9 when the nominal yield strength of the HSS member exceeds 355 MPa.
The current implementation of the Canadian code does not support the following features: