Bugs are found from time to time and in our effort to be trustworthy and transparent, they are posted here as well as appearing on the MASS Welcome Screen

The known bugs page has moved from the MASS website to the MASS section of the CMDC website. The following list consists of a selected list of known bugs. For questions about specific bugs, or to report a bug, contact mass@canadamasonrycentre.com.

[Fixed] Sometimes MASS crashes when I try and launch the program before the Welcome Screen appears (on Windows 10).

Go to our post on MASS Crashes for detailed information on why this might be happening and what can be done. A specific crash featured at the end of that post has been addressed in the upcoming release of MASS Version 3.0.

[Fixed] Critical buckling load can be overestimated for some reinforced walls under high axial load

Under a very specific combination of conditions, MASS may calculate the critical axial load for a reinforced wall, Pcr using both (EI)eff of 0.4EmI0 and Φer of 0.75, resulting in a Pcr value that incorrectly combines aspects of reinforced and unreinforced analysis. A full write-up of this bug can be found here and it has been addressed in the upcoming release of Version 3.0 as well as a retroactive update of Version 2.2 (MASS Version 2.2.1).

[Fixed] “Unhandled Design” message returned for some shear wall designs

A bug has been found where a shear wall passing moment design then failing shear design would display an “unhandled design” error for moment design under certain conditions. This would occur when the moment design would pass using the highest block size and strength made available via user input selection. When shear walls in this situation then fail shear design, MASS attempts to find another passing configuration using a higher unit size and strength. However, since there are no larger sizes and higher strengths to attempt, the “unhandled design” would be displayed rather than correctly showing the user the shear design failure message. This has been fixed in the upcoming release of Version 3.0.

[Fixed] Reaction force drawing are showing incorrect values

Previously, MASS™ would show incorrect vertical reaction forces or no force at all on all shear wall support reaction drawings. This has since been addressed and the support reactions are now correctly displayed. It should be noted that this bug was only a display issue and had no effect on design calculations. This bug was initially addressed for some shear wall designs with the release of Version 2.2 but has been completely addressed upcoming release of Version 3.0.

[Fixed] When opening a project from Windows explorer, the MASS welcome screen appears rather than the actual project

When double clicking a “.masonry” project in windows explorer with MASS Version 2.2, rather than open the project file directly, the welcome screen appears where the user must again navigate to the project file in order to open it. This has been addressed in the release of MASS Version 3.0.

[Fixed] Sometimes old MASS projects aren’t opened properly. What is going on?

Previously in MASS™ Version 2.1, there was a bug where many project files created in Version 1.0 could not be opened. This has been addressed with the release of Version 2.2.

[Fixed] Slender wall designs fail if the steel does not yield when grout is ignored, even though the analysis used by MASS takes grout into account. Is this correct?

In Versions 2.0 and earlier, No it is not. Previously, if the primary tension reinforcement did not yield for either the grout included or grout ignored analysis, the entire section fails without checking to see if the other method would provide an acceptable design. MASS™ displays passing design results for walls where one of grout included or grout ignored analysis includes yielding tension reinforcement and has a moment resistance that is greater than the factored moment including slenderness effects. This was corrected with the release of MASS Version 2.1.

[Fixed] MASS fails all slender, cantilever walls for having a fixed base. How can a cantilever wall even be designed without a fixed base?

In MASS Versions 1.1 and earlier, all slender reinforced walls needed to have pinned supports at the top and bottom of the wall, in accordance with CSA 304.1-04: The intent of is fixed base end condition is taken into account by using the k=2 factor and provided that all other slenderness criteria are satisfied, slender cantilever walls can now be designed in Versions 2.0 and newer.

[Fixed] When adding loads with imperial units to a wall, MASS™ designs for a smaller moment and shear than expected. Is the program correct?

In MASS Versions 1.1 and earlier, No. While line loads are correctly converted between metric and imperial units, they are not properly applied to an effective 1m section of wall. All imperial loads need to be scaled up by a factor of 3.28 (number of feet in one metre) to be applied over the 3.28 ft section of wall. Since all loads are immediately converted to metric units for design, no other processes are affected. This has been addressed in Versions 2.0 and newer.

[Fixed] Compared to hand calculations, MASS™ requires my squat shear wall to have more horizontal steel than expected to meet minimum seismic reinforcement requirements. Is the program correct?

This depends entirely on the interpretation of the way minimum horizontal steel is defined in the S304.1-04. When MASS™ determines the minimum steel required in order to meet CSA S304.1-04:, a horizontal cross section is used to calculate Ag, rather than a vertical cross section. In the case of squat shear walls, this means that the required area of horizontal steel is higher by an amount directly proportional to the length to height aspect ratio. To work around this, change the seismic hazard index to a value below 0.35 and manually check that the area of horizontal steel in the wall is higher than the minimum 0.00067Ag.

[Fixed] My shear wall with an aspect ratio greater than 1.0 passes both moment and shear design but does not have enough horizontal steel to meet the seismic requirements. What is the cause of this?

The minimum area of steel required to satisfy CSA S304.1-04: is calculated incorrectly, using a horizontal cross section to calculate Ag, rather than a vertical cross section. This means that it is possible for a shear wall with a height to length aspect ratio greater than 1.0 to have a lower than expected minimum reinforcement area.

[Fixed] According to hand calculations the program requires shear steel (in addition the shear resistance provided by the masonry). The program however provides a successful design without the additional steel. Is the program correct?

No, the result the program provides may not be correct. MASSTM Versions 2.1 and earlier cycle through all of the load combinations to determine the maximum factored shear and corresponding location along the wall height.  This routine starts at the top of the wall and checks all points down the height of the wall.  If the factored shear along the height of the wall is constant, the location of maximum shear will be the first point checked.  In MASSTM, this first point is at the top of the wall.  For a cantilevered shear wall, the factored shear profile is going to be constant along the height and therefore the location of maximum shear picked by MASSTM will always be at the top of the wall.  If there is no applied moment at the top of the wall, the factored moment at the location of maximum factored shear will be zero and therefore,  Mf/(Vfdv­is assigned the minimum code value of 0.25.  However, in some cases, depending on the ratio of Vf and Mf, the critical location for shear design might be at the bottom of the wall as shown in this example  since Mf/(Vfdv)  ­may range up to the maximum value of 1.0.  As a result, the masonry shear strength calculated in MASS may be over estimated. This has been corrected with the release of Version 2.2.

[Fixed] The MASS custom unit database is unstable. Is there anything that can be done about it?

Customized units are not recommended when using MASS™ Versions 2.1 or earlier.  The Masonry Unit Database can be unstable and was improved with the release of Version 2.2. Feel free to contact MASS support if you would like a copy of the default database file.

[Fixed] In Version 1.0, on the welcome screen of the program, the icons and corresponding buttons are shifted relative to one another. Is there a way to correct this?

Yes. The ‘Open Existing File’, ‘Create New Beam’, ‘Create New Wall’, and ‘Create New Shear Wall’ may shift if your icon settings on not on default. To alter your icon settings in Windows 7 for example, go to: Start→Control Panel →Display. Choose the ‘Smaller – 100%’ icon setting. This has been addressed in Version 1.1 and the entire welcome screen was redone for Version 2.2.

[Fixed] In Version 1.0, the results the program provides when using imperial units do not seem to agree to those obtained using metric input. MASS™ gives different factored reactions when a load is entered as imperial equivalent 68.58 lbs/ft, (1.0 kN/m). Am I missing something or is there a software error?

This is indeed a software error. It is not the reactions themselves that are calculated incorrectly, it is the conversion factor used within the program. Kips/ft and lbs/ft are converted from kN/m using an incorrect constant. This has been addressed in Version 1.1. Please also refer to the bug concerning imperial loads on walls before using loads with imperial units. This has been corrected in MASS Version 1.1.

Other common inquiries

My computer ID has changed from the original computer ID used to activate MASS™. I can no longer use the program. What can I do?

Please refer to our comprehensive activation guide here.

No one at our company has been able to perform an online activation. What could be the potential cause of this?

Please refer to our guide on how to troubleshoot online activation here.


When the program incorporates the self-weight of an out-of-plane wall, it uses the full height of the wall to calculate the axial load in combination with the internal bending moment. Is this correct?

The program does incorporate the self-weight in this way, and this additional axial load could potentially increase the bending moment capacity of the wall, resulting in an unconservative design. The designer can manipulate the program by checking-off the ‘include self-weight’ checkbox and then manually add an axial dead load to represent the portion of wall they want to include in self weight calculations.

The following two tabs change content below.

Brad Crumb

Brad is a Masonry Design Engineer with CMDC. Starting in 2011, his main role with the CMDC has involved developing the masonry design software, MASS, as well as handling the engineering related technical support questions that come in on a regular basis. If you've called or emailed the CMDC office about MASS, chances are you had the pleasure of meeting Brad.