Starting in 2010, Masonry Analysis, Structural Systems (MASS) has been available as a design tool to engineers across Canada. From day one, our mission has been to provide an effective design resource that saves significant time in the engineering design process without compromising the reliability and integrity of your design calculations. We have received a lot of feedback and always make a sincere effort to keep development costs low by only spending on areas that directly improve MASS.

As of May 15th, 2018, the price of all software renewals and purchases can be seen in the table below:

Compared to prices offered starting in 2013, this is equivalent to only a 1.9% annualized increase.

Full pricing can be found on the MASS website. With these new pricing options, there are a number of other items to keep in mind.

License revenue goes straight to improving MASS

Just to list a few examples, a new in-plane lateral load distribution module, Shearline, was created for Version 2.0 to save time on simple, single storey elevations that generally are not allocated much engineering design time. The most recent major update came in Version 3.0 where the entire scope of MASS was shifted to using the updated editions of CSA Standards for designers working in areas where the 2015 National Building Code of Canada has already been adopted. Between these major releases, minor updates have been made and released to add smaller items like fire resistance ratings, more reliable printing, and an improved launch screen. Throughout the entire process, bugs have been diagnosed, tested, and patched within each minor update to ensure that you can be confident when using MASS. The most recent example of this can be seen in Version 2.2.1 which was released after Version 3.0 which you can read more about here.

Currently, work is being done to expand the scope of MASS to include Chapter 16 seismic design requirements added in the 2014 edition of the CSA S304. This will include shear wall deflections, ductility seismic force reduction factors, ductility verification, and plastic hinge requirements. In addition to the seismic work, a new multi-storey shear wall module is under development to save time for many multi-storey structures.

Licensing revenue goes directly to improving MASS and improving it on a continuing basis.

MASS is well supported and maintained

If you have ever had any issues getting MASS running or have had technical questions about the software’s calculations and overall design approach, you have contacted MASS support. Unlike many software packages that operate using a ticketing system and involve waiting periods and escalations, anyone with a MASS license has immediate, direct access to engineering support through the Canada Masonry Design Centre. We take pride in offering excellent customer support that is knowledgeable and available for when you need it.

MASS Licenses include more than just access to the MASS Software

While the biggest part of the decision to renew MASS is based on getting access to the software, once you have a valid license, other benefits are included at no extra cost. While some programs like to nickel and dime for add-ons and features, every MASS user has access to the complete version with no fine print. When updates are released and the software is improved, you don’t have to pay an upgrade fee. Simply maintaining and renewing your MASS license entitles you to the most up to date version that is available.

MASS license holders also get notified first when a new course or seminar has been made available. The most recent iteration of the CMDC’s Engineered Masonry Design Course was announced and filled within 48 hours by MASS users who had the advantage of being the first to know about it.

Discounts are available for everyone

Everyone likes getting a deal and just because individual renewals go for $220 per person doesn’t mean that’s what you have to pay! There are many types of discounts available that you should not hesitate to take advantage of:

Early-bird Renewal Discount

Chances are, you’ve been linked here from one of our email notifications and if that is the case, you will also see that you can save 15% if you don’t put off your renewal to when your next masonry project comes along. This is available to everyone with a MASS license that needs renewing so act quickly to take advantage.

Multi-User Discount

Have more than one engineer working in your office? We have special office packages for groups of 5, 10, or more engineers that make it cheaper and more cost effective compared to purchasing individual licenses. Click here to see all of the available packages along with pricing. Note that these cannot be spread across multiple locations, which leads us to…

Discounts for Companies spread over multiple locations

If you fit this category and have at least four offices with at least one small office package, you have already been proactively contacted with a special discount offer. These are offered to try and help make up for the fact that the larger offices packages cannot be divided between engineers working from different locations.

Creating software is expensive. Period.

Everything in the software creation process takes a lot of time, energy, and money. From specifications and documentation to programming and quality assurance testing, engineering software cannot be done without significant investment both initially and on an ongoing basis. This is all before factoring in support, website maintenance, license management, and distribution.

You may have also noticed that promotion and advertising hasn’t been mentioned. The MASS software is a tool that is growing in popularity thanks to reputation and word-of-mouth alone! None of the revenue from license sales is used for anything that doesn’t go straight back in to the software you are using today.

Putting the “Not” in “Not-for-Profit”

The MASS software represents a joint venture between masonry contractors (through the not-for profit contractor association: CMDC) and masonry block producers (through the not-for-profit industry association: CCMPA). Together, the masonry industry covers over 75% of software related costs, leaving less than 25% which comes from licensing purchase and renewal fees. There is a good reason why there isn’t another masonry design software package for Canadian designers offered by a private company.

Still have questions?

Feel free to reach out to MASS support with any comments, suggestions, or other feedback regarding this change. While we understand that for many designers, masonry is a component that only comes up on projects here and there. We work very hard to make sure MASS is a product that is cost effective and pays for itself after even just one job. MASS licenses are deliberately priced and subsidized in such as way that it can be accessible to any designer in Canada using masonry in their projects.

If you have any questions, please do not hesitate to call or email the Canada Masonry Design Centre. We are here to help!

The MASS software is a product of a joint partnership between CMDC and CCMPA. CMDC is the authorized provider for MASS Technical Support.

The spots went much more quickly than anticipated but just two days after the course notification was sent out, all of the available seats for the Engineered Masonry Design Course (EMDC) have been filled. There have been quite a few calls that have come in since the last seat was taken and we regretfully cannot accommodate a larger class size. This is a function of our training centre classroom (hosted with OMTC) which can only seat 30 engineers at full capacity.

Classroom ready for the start of the 2018 Mississauga edition of the greatly anticipated EMDC

To be notified when the next course is announced, feel free to contact us and request to be placed on the waiting list. Alternatively, all current MASS users are notified when any new course or seminar is announced. New courses can also be requested on our Course and Seminars pages.

If you have ever designed a multi-storey shear wall and wondered why the moment resistance is less than expected, the reason is likely CSA S304-14: 10.2.8:

MASS automatically identifies shear walls that have an aspect ratio less than 1 and designates them as squat shear walls. Keeping all calculations and design results in accordance with the CSA Standards, it also correctly reduces the moment arm of all steel in tension when applicable which is why there is a reduction in moment resistance. While it is often the first reaction of many users to assume that this behaviour comes from a bug in the software, MASS is behaving as intended.

Multi-Storey Applications

What if you are designing just one element within a larger shear wall where the element has an aspect ratio less than one but the full shear wall does not? Is it correct to be applying the reductions from clause 10.2.8 to elements such as these? Consider the example below:

This example which was used in the Multi-Storey Shear Wall Design article demonstrates an instance where this clause comes into play. The entire shear wall itself is clearly not squat as it’s aspect ratio is 3.2. As it is loaded, it is behaving as a non-squat shear wall so it is not correct to be applying clause 10.2.8 to the design of an individual storey. In order to design this wall in MASS, only the individual elements can be modeled and designed separately. As you can see, the wall input into MASS on its own is designated as a squat shear wall which is where the Total Height input comes in handy: it allows the user to tell MASS that while an element may be “squat”, it should not be treated as such.

“Height” vs. “Total Height”

The scenario described above is the reason multiple height inputs are available in MASS.

Height refers to the vertical dimension of only the shear wall element being modeled while Total Height refers to the vertical dimension of the full shear wall assemblage, beyond just what is being modeled.

If Storey 2 is modeled in MASS without any consideration of the larger shear wall it is apart of, it is designated as being squat as it’s 4/5 aspect ratio is less than one. When the total height is changed to the full 16m, the aspect ratio used to apply squat reductions from clause 10.2.8 increases to 3.2 and the result is an improved moment resistance.

Impact on Design

How much of a change does this make to a shear wall design? Using the example from earlier, when designing using a 20cm, 15MPa concrete masonry unit, taking the total height into account means the difference between using No. 15 and No. 20 bars placed exactly the same. If using No. 15 bars for both designs, the squat version of the MASS file would need to go all the way from a 15 to 30MPa strength unit to compensate. Furthermore, if the masonry and reinforcement properties were both fixed to the same design, the difference in capacity can be seen on the interaction diagrams below:

Comparison of moment envelope curves for shear wall design both including and neglecting the total height

For the critical load combination (#15: 0.9D + 1.4W), this means that the moment resistance of the wall is reduced from 1333.5kN*m to 1111.5kN*m, or by 222kN*m, simply by not taking the aspect ratio of the full wall into account!

This effect is further demonstrated in the example below where 70% of the vertical reinforcement is concentrated on either end of the wall. This significant reduction in moment is a direct result of a reduced moment arm for the steel that is in tension and furthest away from the compression zone. Note that this design uses the exact same materials simply arranged differently.

Comparison of moment envelope curves for shear wall design both including and neglecting the total height

There is now a 330 – 430kN*m reduction in the moment resistance compared to the 200 – 275kN*m reduction observed when the reinforcement is evenly distributed. One thing to note for all of these comparisons is that the difference in moment resistance diminishes when the applied axial load approaches P_f,max.

For those curious, a comparison of the uniformly distributed reinforcement and concentrated end steel designs can be found by expanding the section below:

If you have any questions, please do not hesitate to call or email the Canada Masonry Design Centre.

The MASS software is a product of a joint partnership between CMDC and CCMPA. CMDC is the authorized provider for MASS Technical Support.

National Masonry Design Programs is proud to announce the official release of Masonry Analysis Structural Systems (MASS^TM) Version 3.0.

Major Changes in MASS Version 3.0

The major changes are listed below while the full list of changes can be found on the MASS website here as well as in Section 1.6 of the MASS help files.

Design Codes and Standards

As mentioned above, Version 3.0 adapts all masonry design procedures from Version 2.2 to using current design standards. Two papers outlining these changes were published and presented by Dr. Drysdale, Dr. Banting, and David Stubbs at the recent 13^th Canadian Masonry Symposium hosted by the Canada Masonry Design Centre (CMDC) and Dalhousie University. These papers can be found here (Part 1: Non-Seismic Changes) and here (Part 2: Seismic Changes). With the exception of seismic minimum reinforcement requirements, all of the changes within the current scope of MASS are considered non-seismic. The next release of MASS which is already in development will increase this scope to include higher levels of ductility performance, as well as the rest of the newly added CSA S304-14 Chapter 16: Special Provisions for Seismic Design.

New Project File Format

In an effort to reduce confusion around which projects have been designed in accordance with which codes and standards, the project file format “.masonry14” was created which designs exclusively to the current standards. MASS Version 3.0 can still open old projects, however upon opening them, you will be prompted to “Save As” a “.masonry14” project as the design results may be affected. An article explaining the difference and compatibility can be found online here.

Additional Bug Fixes

As software issues are discovered, they are posted on our “Known Bugs” page which is linked from the MASS website homepage and kept up to date. There was one bug recently discovered internally at the CMDC what was also present in Version 2.2 which was re-compiled at MASS Version 2.2.1 and included in the Version 3.0 download. An explanation of the bug can be found here and a Version 2.2.1 explanation can be found here.

How to upgrade

Step 1: Open the Notification email and follow the link to the MASS Upgrades page:

Didn’t receive the email? Check with your admin staff or local IT professional who may be in charge of software licensing for your company. Only MASS website account holders or manually assigned users will have been sent the notification email. In the event that you require access to the download but someone else in your office was sent the email, simply using a forwarded copy with the credentials included is enough to access the download (Note that this does not require the account password or other more sensitive information such as address. We do not save or even have access to payment information)

Step 2: On the MASS upgrades page, select the option to download MASS Version 3.0.

Step 3: Copy and Paste your email address and corresponding serial number and clock “DOWNLOAD” to begin the download:

Note: Even a change of one typed character is the difference between the download working and not being found in the database. Please double check your entries or copy and paste from the email notification which has been pulled form the same database.

Step 4: File will begin downloading:

For most web browsers, the keyboard shortcut CTRL + J can be used to open the list of downloaded files.

Step 5: While the package is downloading, it is highly recommended that all existing versions of MASS be uninstalled prior to installing MASS Version 3.0. For assistance on how to uninstall programs, click here.

Step 6: Once the file has finished downloading, the directory can be extracted and opened to show the following files:

After uninstalling all prior versions of MASS (including Version 2.2), run the “setup.exe” file to install MASS Version 3.0.

There is also a video available on the downloads page outlining the same process for MASS Version 2.0 which is essentially unchanged. For assistance, please do not hesitate to contact the authorized MASS technical support provider, Canada Masonry Design Centre.

Back in April of 2016, the release of MASS Version 2.2 marked what was thought at the time to be the final version of MASS which designed using the old 2004 versions of the CSA Standards. In the early development stages of Version 3, before any technical changes were implemented, some user interface items (ie. MASS Welcome Screen) and other common headaches (ie. Printing, activating) were also added to help ease the transition of switching to a new design code in MASS.

The discovery of a new bug prior to the release of MASS Version 3.0 is included on our Known Bugs page as well as having a full explanation available here.

While the bug was investigated and a fix was found and tested, the decision was made to add the fix to Version 2.2 as well in an effort to make it age a little better. While old versions are not supported and there are no plans to release updates to old versions, an exception was made for two reasons.

1. The bug discovery and fix occurred shortly ahead of the Version 3.0 release
2. Version 2.2 is the last version that will design using the old 2004 CSA Standards as well as open the old “.masonry” project files (click here to read more on the new MASS project file format)

What is different in Version 2.2.1?

MASS Version 2.2.1 is identical to Version 2.2 with the exception of a fix to the bug explained here.

How to upgrade Version 2.2 to Version 2.2.1

1. To upgrade Version 2.2 to Version 2.2.1, first uninstall MASS Version 2.2. For assistance on how to do this, click here.
2. Once Version 2.2 is successfully uninstalled, go to the Version 3.0 installation folder and run the file named “MASS221.msi”

The version can be checked within MASS by clicking “Help” on the top toolbar and then select “About MASS“.

Please do not hesitate to call or email with any questions. Click here for a full outline of the various services offered by CMDC (the authorized technical support provider for MASS)

When software bugs are found, notifications are posted in the MASS website Known Bugs page, on the MASS welcome screen, as well as here on the CMDC website software blog in an effort to be transparent and keep all MASS users informed. This issue was found within our own office as a result of an inquiry from a MASS user that resulted in this post. The bug was found some time after and as a result, the fix was incorporated into MASS Version 3.0, as well as a modified copy of Version 2.2 specifically to address this issue (click here to read more about Version 2.2.1).

This post outlines the conditions required to trigger this error, the designs where this could have affected design results, the details of the bug itself, and how to check to see if this bug is present in any MASS project.

Jump straight to:

• Bug Summary
• Background information
• What types of designs might be affected
• How to check if a design is affected
• Example
• Our Response

Bug Summary

Under a very specific combination of conditions, MASS may calculate the critical axial load for a reinforced wall, P_cr using both (EI)_eff of 0.4E_mI₀ and Φ_er of 0.75, resulting in a P_cr value that incorrectly combines aspects of reinforced and unreinforced analysis.

This bug only affects designs where all of the following conditions are met:

1. vertical reinforcement is not in tension
2. load combinations with steel in compression also govern the design
3. the wall experiences slenderness effects but is not a slender wall (kh/t > 30)

If MASS designs a wall where the vertical steel is in tension, all of the software’s results are correct. The same is true if any of the other conditions listed above is not true. The unlikely combination of circumstances is the reason why most wall designs are not affected and also why this bug has not been discovered until recently. This has been addressed in MASS Version 3.0 as well as in an updated Version 2.2.1.

Background information

If a wall is reinforced, why is it a problem to use the reinforced reduction factor when it comes to slenderness effects?

There is no problem as long as everything else in the calculations is also treating the wall as if it were reinforced. The issue comes from the way in which MASS sometimes treats the wall as if it were unreinforced when the steel is not in tension. This is done intentionally as ignoring the steel allows the software to use CSA S304 chapter 7 clauses governing the analysis of unreinforced walls when it is beneficial. This also assumes that the addition of steel to an unreinforced (but still grouted) wall will not reduce its capacity. For a full explanation on RM/URM analysis for reinforced walls, click here.

Differences between treating the wall as reinforced vs. unreinforced

Reinforced analysis compared to unreinforced differs in two ways when it comes to determining slenderness effects of a wall:

1. Φ_e vs. Φ_er – Resistance factors for member stiffness used for slenderness effects
2. (EI)_eff – Effective stiffness for consideration of slenderness

Resistance Factors – Φ_e vs. Φ_er

There are two different resistance factors that are used in calculating the critical axial compressive load used for determining slenderness effects; Φ_e for unreinforced walls, and Φ_er for reinforced walls. Click the heading below to expand the CSA references from which these resistance factors are based upon.

As stated at the beginning of this post, the bug is that for reinforced walls, the reinforced reduction factor is sometimes incorrectly applied, using Φ_er rather than Φ_e. On its own, this would not be an issue, however, when combined with the reinforcement assumptions used in determining effective stiffness, there can be a “mixing” of assumptions that results in this bug.

Effective stiffness – (EI)_eff

Similar to the resistance factors, the formula used to determine effective stiffness for slenderness effects is a function of whether or not the wall is reinforced. Effective stiffness, or (EI)_eff, for unreinforced walls is 0.4E_mI₀ while (EI)_eff for reinforced walls is 0.25E_mI₀ (where the applied eccentricity is relatively low, below the Kern eccentricity). Click the heading below to expand the CSA references related to effective stiffness.

Reinforced walls with low eccentricities have an effective stiffness capped at 0.25E_mI₀. Compared to 0.4E_mI₀ which is used for unreinforced walls, there is a 37.5% reduction in stiffness simply for using the reinforced equation for the same wall design. Taking advantage of the unreinforced effective stiffness is what also mandates the use of Φ_e rather than the higher Φ_er.

What types of wall designs are affected?

As mentioned in the summary shown here,

• vertical reinforcement is not in tension
  • c is greater than d for any bar
• load combinations where c exceeds d also govern the design
  • Load combinations with higher axial loads are more likely to have the neutral axis exceed d while load combinations with both low axial load applied with high bending moment are typically closer to a wall’s interaction diagram envelope curve
• the wall experiences slenderness effects but is not a slender wall
  • Slenderness ratio, kh/t, is greater than 10 – 3.5[e₁/e₂] specified in S304-14: 10.7.3.3.1 but less than 30 where axial load is governed by S304-14: 10.7.4.6.4

The only wall designs affected by this bug are those which have axial loads so high that the steel is no longer in tension AND experience slenderness effects without being classified as slender walls (S304-14: 10.7.4.6). Many wall designs that are governed by slenderness effects also require compression forces in masonry coupling with reinforcement in tension and are therefore not affected. For example, single spans with only self-weight and some nominal loads transferred from roof level are often not loaded with enough axial load to move the location of the neutral axis beyond the depth of steel in the wall.

Additionally, in order for a design to be impacted by the presence of this issue, the load combinations where the circumstances above are present must also be critical to the design. Load combinations with the highest axial loads (for example: 1.4D) are most likely to also be governed by load combinations using high lateral loads combined AND lower axial loads (for example: 0.9D + 1.4W).

It might even be easier to rule out the wall designs that are not affected:

• all slender walls are unaffected and correctly handled within MASS
  
• all walls using vertical reinforcement in tension (bars are ignored in compression as they cannot be adequately tied) are unaffected
• all walls that do not have any slenderness effects are not affected
  

Most wall designs fall into one (or more) of these three categories and it takes a special combination of circumstances to trigger a design that results in this bug affecting software result

How to tell if a design is affected

Check to see if the steel is in tension

Look at the location of the neutral axis and compare it to where the vertical bars are placed. If the distance to the neutral axis, c, is less than the depth to the layer of reinforcement, d, then the steel is in tension and your design is not affected.

In this example, a wall constructed using 15cm units (thickness of 140mm) can be checked to see if the steel is in tension by comparing the Neutral axis value in the Simplified Moment Results window to the steel depth, d, which is placed in the middle of the wall (b_w/2).

Steel is in tension (c<d)

Check to see if that load case governs the design result

As mentioned earlier, the load cases resulting in the steel not being in tension tend to differ from the load cases that govern the final design result (1.4D compared to 1.25D or 0.9D + 1.4W). When this is the case, the design is unaffected by the result. The example file highlights this aspect where the load combination resulting in steel being ignored (L.C. #1) is not critical to the design. In this case, load combinations 2 and 3 have total factored moments that are closer to the envelope curve which are based on the correct critical compressive axial load.

Out-of-plane wall designs tend to be governed by load combinations that combine the largest lateral load with the lowest axial load which are more likely to include steel in tension.

Note: To recreate this example for yourself, design a 3m tall, simply supported wall using 15cm, 15MPa units. Apply an unfactored axial dead load of 60kN, turn off self-weight, and apply an unfactored uniformly distributed wind load of 1 kN/m (or 1 kPa when considering a 1m length of wall as is the case for MASS wall modules). When designing for moment and deflection, at the first thing that will happen is that the wall will correctly pass being designed as unreinforced. For the purposes of highlighting this bug, de-select the 0 bars/cell option, effectively forcing reinforcement to be placed in the wall and skipping any iterations that are reinforced.

If the wall design is affected, compare the M_r to the manually adjusted value of M_f,tot

If the bug is present in a MASS project, the total factored moment resistance can be adjusted using the following expression:

M_ftotadjusted represents the adjusted value for the total factored moment taking slenderness effects into account

P_cradjusted represents the adjusted critical axial compressive load

P_crMASS is the critical axial compressive load calculated by MASS for load combinations where the bug is present in the results.

All other terms are defined within the CSA S304-14.

Both a derivation of the P_cradjusted expression as well as an example demonstrating how to use it can be expanded in the two sections below by clicking on each heading:

It is expected that most designs will not meet all of the criteria for the bug to be present as the reinforcement is in tension for most reinforced wall designs. For those designs where the bug is present, it is possible for the the marginal difference in total factored moment to result in a failed design which would have been thought to have passed moment and deflection design. As mentioned earlier, the specific and unlikely combination of circumstances required to trigger this bug within MASS is the likely reason why it has remained undiscovered for so long.

Our Response

Bugs of this nature are taken very seriously. It was discovered in-house but not until very late in the Version 3.0 development process after it had been initially thought to be complete. As a result, the bug was investigated and a fix was added to Version 3.0 as well as to Version 2.2 in the form of MASS Version 2.2.1 (included in the installation directory for Version 3.0 – click here to read more). It has also been posted on our Known Bugs page where it links to this article.

If there is any question regarding the integrity of the results for a specific MASS project file, please feel free to contact CMDC directly. As the authorized MASS technical service provider, CMDC is available to help designers understand the specifics of identifying this issue, as well as any other masonry related technical questions. Click here for more information on technical assistance offered by CMDC.

Length

A beam’s length represents the total length of the entire modeled assemblage including any overhanging length on the outside edges of the supports. This value is typically entered in first and must accommodate the length of the opening above which the beam is spanning as well as the bearing plates on either side. Any additional masonry outside of the primary span is not used when distributing loads and determining the factored moment or shear that must be resisted by the beam. Once specified for a new beam design, a clear span,explained below, is then assumed based on the length needed for bearing on either end.

Clear Span

The clear span refers to the length of the opening above which the beam is spanning. While a beam’s length is typically entered first into MASS, it is also possible to start a MASS design by specifying a clear span and let the software automatically fill in the total beam length based on the length required for bearing on either side, rounded to the nearest modular cell length.

Bearing Length

The bearing length is defined as the length along the beam under which a high concentration of stresses due to concentrated loads is transferred to the supporting structure below. It can be spread over a steel plate or an area of masonry under compression. The default bearing length of 300mm was chosen for MASS because it is the longest allowable bearing length (CSA S304-14: 7.14.1.2) that can use a triangular load distribution and not require additional detailing (ie. using a rocker plate) to ensure a rectangular load distribution. For triangular reaction distributions, the centre of reaction is at one third of the bearing length away from the edge of the clear span and for rectangular distributions, the distance to centre of reaction is at half of the bearing length.

Design Length

Design length is the distance between the centre of reactions between beam supports. It is less than the beam length and greater than the clear span, used to determine the factored moment and shear. For example, checking MASS results by hand and looking to replicate the maximum factored moment at mid-span for a simply supported beam, the design length is used in M_f = wL²/8.

Quick demonstration – From masonry elevation to design using MASS

Starting with an elevation containing an opening with masonry extending above and on either side, a portion must be designated as part of the modeled beam. This example where two courses are assumed for the beam’s height, the full beam length extends one full masonry unit to either side which allows room for the bearing area in addition to the clear span.

For the same elevation, it is also possible to design a single course beam or go all the way up to four courses which can all result in acceptable solutions. Smaller beams have reduced moment capacity mainly from a smaller moment arm between coupling tension and compression forces while taller beams can have intermediate steel requirements (S304-14: 11.2.6.3) and may also have to satisfy additional provisions for deep beams (S304-14: 11.2.7) and deep shear spans (S304-14: 11.3.6). Choosing how a beam is modeled is left to the discretion of the designer.

For all masonry beam designs, a load path for vertical loads must be assumed for transfer to the supporting structure below. The default bearing area with a bearing length of 300mm is shown below resulting in a triangular distribution of the reaction force. Had the bearing length been longer than 300mm, the reaction would have been spread over a rectangular distribution (S304-14: 7.14.1.2).

In order to determine the design length, the centre of each reaction force must be determined. For a triangular reaction distribution, this location is one third of the bearing length away from the edge of the clear span for each support. (Rectangular distributions have a centre of reaction point half way through the bearing area)

The locations of the reaction forces expressed as point loads is then used to determine the design span. They are also where MASS draws the support points underneath the bearing plates in beam drawings.

Note that the difference in unit arrangement between the figures above and MASS has no impact on the design as fully grouted masonry. MASS always starts an assemblage with a full unit however starting with a half unit as was done in the illustrations above is functionally the same design.

As always, feel free to contact us if you have any questions at all. CMDC is the authorized service provider for the MASS software which is a joint effort of between CCMPA and CMDC.

The vast majority of masonry walls designed to resist out-of-plane bending are supported at the top and bottom, spanning vertically. Once you start looking at designs where a wall is spanning horizontally between columns, intersecting walls, or other supports, you are no longer within the scope of MASS. This does not mean that MASS cannot be a useful tool in designing a  horizontally spanning wall! Continue reading to see how you can manipulate the software to assist you in your design.

For a quick checklist summary, click here to jump down the the end of this post.

Disclaimer: By using MASS to design horizontally spanning walls, it is up to you, the engineer, to ensure that all of the differences between vertical and horizontal spanning walls are properly accounted for within MASS. If there is any doubt of having a complete and comprehensive understanding of how to model these differences, it is best to perform these calculations by hand.

In order to design a horizontal span using the MASS wall module, it is important to understand the key differences between vertical and horizontal spans:

1. Geometry

2. Masonry strength in relation to the masonry bond pattern

3. Axial load

Before diving into these differences one by one, it is first valuable to review the base assumptions that area made within the MASS out-of-plane wall module. These cannot be changed and must be accounted for in other ways.

1. The wall is supported at the top and bottom
2. The masonry units are placed horizontally, with the bed joint parallel to the ground
3. Moment resisting reinforcement is placed vertically in the masonry cells

Even with these constraints built into the software, it is possible to accurately analyze and design a horizontally spanning wall using MASS.

Assemblage Geometry

When designing a horizontal span using MASS, there is no way to change the orientation of the entire wall. As mentioned above, the supports are always placed on the top and bottom of the wall so to account for this, the actual wall being modeled must be rotated 90 degrees to turn a horizontal span to a vertical span within MASS. This same principle applies to the span length, which must be input in MASS as the wall height.

When making the 90 degree rotation, everything about the wall is rotated – including the orientation of the bond pattern! This leads us to the next item in need of consideration…

Masonry strength in relation to bond pattern

Unless you are building a wall with units stacked on their sides, there is no way to alternate the bond pattern within MASS to have the software automatically take this into account on your behalf.

Unlike poured concrete, masonry assemblages do not have the same tensile and compressive physical properties in all directions. The direction of the bond pattern matters and is taken into account within the CSA S304 design standard for both unreinforced and reinforced masonry.

Unreinforced walls in bending depend on tensile strength

The bending capacity of horizontal spanning walls is generally governed by the tensile strength of the masonry assemblage, f_t (See note below for exceptions). Vertically spanning walls have a continuous bed joint where a crack is likely to form without intersecting the unit itself. This results in the vertically spanning tensile strength being less than that for horizontally spanning walls, working to your advantage by increasing the wall’s bending capacity!

This is taken into account in the CSA S304-14 in Table 5 where the distinction is made between tensile strength normal and parallel to the bed joint.

Note the bottom * indicating that these only apply for 50% running bond pattern. Sorry stack pattern fans! You’re stuck using 0.40MPa.

Changing tensile strength in MASS

You can account for this change within MASS by unchecking the “Auto” functionality and manually typing in the correct value to be used in your design.

For example, if designing an unreinforced block wall, the corresponding Table 5 value for f_t is 0.80MPa for horizontal spans. Since the default value MASS would normally use for a vertical span is 0.40MPa, the “Auto” box can be unchecked and 0.4MPa can be replaced with 0.8MPa.

Keep in mind that when “Auto” is deselected, all 4 values must be entered, including the ones that may not be relevant.

Note: Due to the nature of horizontally spanning walls having little or no applied axial loads, unreinforced walls spanning horizontally are typically governed by tensile strength.  As is the case for vertically spanning unreinforced walls, there are other failure modes that must also be considered (linear compression of masonry, maximum allowable eccentricity, and ultimate compression at failure) however these all become important with the presence of applied axial load. Provided that there is no axial load and 0.6f’_m is greater than f_t, failure of the extreme tensile edge will govern the wall’s capacity.

Reinforced walls in bending must have their compressive strength adjusted as well

The introduction of reinforcement to your design allows the wall to bend well beyond its linear elastic capacity crack and have all tensile forces resisted by horizontally placed steel. The ultimate compression strength that couples with this steel still needs to be manually adjusted to take into account the direction of compressive stress relative to the direction which f’_m is based upon. The CSA S304 standard uses the chi factor to accomplish this in clause 10.2.6.

While MASS assumes that the head joint is perpendicular to the supported edges, it is in fact parallel for a horizontally spanning wall which must be taken into account by chi which ranges from 0.5 to 1.0, seen below:

For horizontally spanning walls, any compression force that is coupling with reinforcement must use the correct value of the chi factor which for vertically spanning out-of-plane wall is always 1.0. Click here to read more about the chi factor and masonry beam design. Whether or not the correct chi value is 0.5 or 0.7 depends on whether the compression zone exceeds the face shell thickness, extending into the grouted cells. MASS automatically changed chi for beam design as beams are within the originally intended scope of MASS. For horizontal wall spans, it must be manually checked. Using 0.5 without checking is conservative but taking advantage of chi = 0.7 is very easy to check. Upon completing a moment and deflection design, multiply the neutral axis depth, c, by Beta1 (0.8 for nearly all cases) and compare that value to the thickness of the masonry unit face shell thickness.

Table 4 is shown below for quick reference of f’_m values before the chi reduction factor is applied:

Changing compression strength in MASS

The reduction in f’_m can be taken into account by unchecking the “Auto” selection box for masonry strength and manually typing in the adjusted value. For a 15MPa block, the corresponding grouted compressive strength is 7.5MPa (Table 4, above) and the reduction factor, chi, for interrupted grout is 0.5. To account for this in MASS, a custom grouted strength of 3.75MPa can be entered. In the event that the compression zone does not extend into the grouted cells, it is better the ignore the effects of grout and use only the compressive strength of the bonded face shell area. Not only can you take advantage of using a higher f’_m value, but you also no longer have any interrupted grout and a chi value of 0.7 can be used. For that same 15MPa unit, hollow f’_m is 10MPa (Table 4, above) so to account for this in MASS, a custom hollow f’_m value of 7MPa can be specified.

Continuing from the earlier unreinforced example, these changes can be made to MASS by changing the solid and hollow custom f’_m values.

MASS automatically assigns hollow and grouted f’_m values to each part of a partially grouted wall cross section. By applying a reduction of 0.7 to the hollow strength and a 0.5 reduction to the grouted strength, MASS will correctly take each chi factor into account. As a bonus, MASS will also check the capacity of the wall ignoring the effects of grout which can will provide an even higher moment resistance for cases where the compression zone extends barely beyond the face shell.

Once this change is made, MASS will use the entered values rather than using the ones from CSA S304 Tables 4 and 5.

Axial Load

As is always the case for regular wall design, axial loads (dead, live, snow, and wind uplift) work in combination with the internal coupling stresses of masonry in compression and steel in tension to resist out-of-plane loading. A key difference for horizontal spans is that unless there is an applied horizontal compression force on the wall, the internal forces resisting bending are acting perpendicular to the vertical axial loads (including self-weight). When determining the strain profile at failure for bending in the horizontal direction, there is no added compression force resisted by the cross section to resist applied axial loads.

Ensuring zero axial load in MASS

At first glance, this sounds like something that doesn’t need added consideration. After all, how difficult is it to not apply axial loads? The thing to keep in mind is that MASS automatically calculates and applies self-weight to wall designs by default. To perform a design with a factored axial load of zero, simply uncheck the self-weight option at the bottom of the MASS Loads tab and check that your P_f and P_r values are actually 0.0kN.

Check wall in vertical direction

If there are vertical loads applied on the horizontally spanning wall, the wall must still be able to resist those loads as well as the corresponding accidental eccentricity in accordance with CSA S304-14: 7.7.3 or 10.7.2 for unreinforced and reinforced walls, respectively:

This means creating a new wall design where the wall is modeled normally (height of horizontally spanning wall is actually input as the height – imagine that) with only the axial loads applied. MASS will take these minimum primary moment clauses into account on your behalf when checking the wall.

Final Summary

As a quick and easy recap, three key aspects of horizontal bending can be considered to design horizontally spanning walls using the MASS Walls module.

1. Assemblage Geometry

   • Rotate the wall 90 degrees and enter the horizontal span as the height in MASS

     • While MASS thinks it is designing an effective m length of wall, making this adjustment allows MASS to be useful for designing an effective m height of wall

2. Masonry Strength relative to bond pattern

   • For unreinforced masonry, manually adjust f_t in MASS based on CSA S304-14: Table 5

     • Hollow f_t can be increased from 0.4MPa to 0.8MPa and grouted f_t can be increased from 0.65MPa to 0.85MPa.
     • This only applies to 50% running bond (stack pattern exempt)

   • For reinforced masonry, manually adjust f’_m in MASS based on CSA S304-14: 10.2.6

     • Hollow f’_m in MASS must be reduced, multiplied by chi = 0.7
     • Grouted f’_m in MASS must be reduced, multiplied by chi = 0.5

3. Axial Loads

   • Ensure that factored axial load and axial load resistance are both zero

     • Uncheck the apply self-weight option in the loads tab which is enabled by default

   • Confirm that wall still has adequate capacity to resist the applied vertical loads.

     • Create a new wall module with only axial loads applied to check capacity in the vertical direction

Upon taking these items into consideration for your design, designing walls that span horizontally is a breeze!

As always, feel free to contact us if you have any questions at all.

CMDC is the authorized service provider for the MASS software which is a joint effort of between CCMPA and CMDC.

MASS Version 3.0 introduces a new set of 2014 masonry standards which are used for calculations and designs previously done using the 2004 versions. It has been in development over the past half year and is just about ready for release. While all of the individual changes have been tested in great detail, CMDC also uses new release candidates in-house for all masonry design work for a period of time to ensure there are no unintended consequences when it comes to making changes to the code. This post outlines the changes to MASS that are new to Version 3.0 and lets you know how you can get an “insider preview” before the official release.

What is new in Version 3.0?

MASS Version 3.0 is the first version of the software to design using the updated CSA S304-14 masonry design standard. All calculations as well as equations, code references, and bitmap symbols have been updated to bring MASS functionality from older versions to now design with this new standard. The biggest change is found in shear calculations for beams, which has been overhauled within the standard to more closely follow the process used for reinforced concrete. The scope of MASS Version 3 has not been changed from Version 2.2. Below is an overview of other changes made to MASS Version 3.0 which can be expanded upon by left-clicking the header.

The biggest technical changes that affect MASS in its current scope include:

1. For reinforced masonry, a 0.6 factor has been implemented to more accurately reflect the non-linear behavior of masonry in compression. Previous version of MASS used a factor of 0.5 which was not part of the S304.1-04 standard but instead implemented by the judgement of CMDC as “phi,linear”
2. No. 30 bars have been removed from all MASS modules in accordance with the changes to S304-14: 12.1.2
3. Minimum steel areas and ratios were reduced
4. Maximum bond beam spacing when bond beams are used to resist in-plane shear now takes wall dimensions into account.
5. Intermediate steel placement for beams has been changed
6. Deep shear span conditions have been changed and beams no longer automatically fail shear design without further analysis
7. The masonry component of beam shear resistance is no longer divided by 2 for beams without stirrups
8. Maximum stirrup spacing is no longer limited by d/2. Much more has been written on this topic here
9. Factored shear is now designed at distance dv rather than d away from the face of the support

Note that the addition of Chapter 16 of S304-14 falls outside the scope of MASS however it is the next order of business to add seismic design (including the ductility verification).

If you have more specific questions regarding changes to the masonry design standards, please do not hesitate to contact CMDC. Below is the FAQ which will be updated as more questions roll in:

Do I need to upgrade from Version 2.2?

No. This release is optional, only intended for those looking to start designing using the 2014 CSA standards. Once you have transitioned to designing using the more recent building codes, you will want to no longer be designing using the older standards.

Does signing up to use Version 3.0 mean no longer using the version installed now?

No. in fact, unlike other MASS releases, Version 3.0 has been designed specifically to be run alongside your current Version (2.2 is the newest release designing in accordance with 2004 standards). Even the file structure has been changed so that you do not have to worry about designing a project using one version and accidentally switching CSA standards by opening it using the other version. Read more on the new “.masonry14” file type here.

If I am interested, how do I get a copy of Version 3.0?

To start using Version 3.0, contact CMDC to request a copy today to be sent a download link with instructions.

What is next for MASS?

Chapter 16 of the 2014 CSA S304 Standard introduces new steps that can be taken to obtain higher seismic force resisting system ductility performance. An Rd value of 3.0 for non0squat shear walls with a detailed plastic hinge can now be obtained compared to 2 which was the highest achievable value in the 2004 edition. Multi-storey shear wall design is also being worked on which will be incorporated in a new module. If you would like to request a new feature, please do not hesitate to let us know!

In order to be able to activate MASS, you need to know your serial number which starts with the letter B and is 31 characters long.

The example used here will be: BHHI0C0I00A1F1GC8F822M1JGWZSJ6C

You can find it on your MASS website dashboard (link will open in a new tab). Don’t have a serial number? You can purchase yours on the MASS website store by clicking here.

If you have an internet connection, the easiest way to activate is Online

If you’ve already tried to activate online and it didn’t work, click here. If you don’t have any internet connection at all, click here.

For an online activation, all you need to do is enter your serial number and click Activate.

Once you have clicked Activate, a form will open requesting your information. Enter this all in and then click Submit.

You’ll know it worked if you see the following before the Serial Number Registration window is closed

If you are getting a message saying that you don’t have an internet connection but you can still receive emails and view web pages, you aren’t alone! Click here to quickly get around this error.

When you are taken back to the main Registration Key Code window, you’ll notice that next to License status, it will list an expiry date. At this point, you are activated and can close the window. The welcome screen will show your updated activation status the next time you launch MASS as well.

No internet? No Problem!

We’ve always had the option of activating offline because not every computer has internet and even for the ones that do, there can be problems that come along. Click here to jump to the Offline Activation guide. Please be advised that this involves contacting MASS technical support so activation may not be possible outside of regular business hours.

Still looking for answers?

Please do not hesitate to call or email CMDC for all technical and non-technical software inquiries. Among all of the many cervices provided by CMDC, timely and effective technical support is always just an email or phone call away!