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 MASS software is a useful tool for designing the individual structural elements of a masonry building. While there is a shearline module for simple, single-storey elevations, there is no such equivalent when it comes to multi-storey shear wall design (yet). It is left to the designer to model each element of their shear wall within MASS in a way that accurately represents its behaviour. This article will touch on a few of the major aspects that come up when using MASS for multi-storey designs.

To jump straight to a specific aspect, click the heading links below:

• Load Distribution
• Total Height
• Top End Fixity

Click here to jump straight to the summary. 

Load Distribution

Before diving into the multi-storey specifics of shear wall design, it is useful to first recall the scope of the shear wall module in MASS.

Shear wall module scope:

The shear wall module in MASS designs an individual shear wall element for in-plane moment and shear based on the loads that are applied to that individual element.

The shear wall module can be used for multi-storey buildings so long as the designer has taken into account the various ways in which a shear wall element interacts with the structure around it.

This includes:

• The accumulation of axial loads applied above the storey being designed
• The accumulation of lateral loads applied above the storey being designed
• Any overturning moments resulting from lateral loads applied above the top of the storey being designed

Example Exercise

Consider the example below, where the second storey of a four storey shear wall is being designed using MASS. In order to design the second floor shear wall element, all loads must be distributed to the top of the wall from all of the walls above. Each storey is 4m tall and all dead loads include self-weight.

Before expanding the solution, it may be a worthwhile exercise to calculate the solution yourself to test your skills.

Note: All axial loads are assumed to be placed at the centre of the wall and evenly resisted by the full cross section (no load dispersion is considered within the section). In cases where axial loads are applied with some eccentricity, this can be accounted for in MASS using an applied moment with a moment arm equal to the eccentricity of the load.

While distributing loads makes up the majority of the work needed to design multi-storey shear walls in MASS, there are still three other important aspects to consider.

Total Height

It is possible that while the full shear wall is not considered “squat”, an individual storey may have a height to length aspect ratio less than 1. In this case, it is important to change the total height to match the height of the full shear wall so that MASS doesn’t treat the individual storeys as squat shear walls. By default, the total height is set to the same value as the shear wall height so if it is unchanged, there may be an unnecessary reduction in moment resistance.

A full article explaining the difference between “Height” and Total Height” can be found here, including examples showing between 15% to 24% of moment resisting performance losses for not taking the total height into account.

End Fixity

When looking at a shear wall element within a larger shear wall, the objective is to take all aspects of being part of a larger shear wall into account. While there is an option in MASS to fix the top of a shear wall from rotating, the effect on the design can be seen in the difference in bending moment profile below:

Applying a rotational fixity at the top of the wall effectively divides the moment between the top and the bottom of the wall’s supports. While the “Fixed (R)” end condition was added to MASS for the purpose of shear wall designs with significant masonry above which prevent rotation, the scenarios where it is appropriately used would more closely resemble what is pictured below, taken from section 5-7 of the MASS Help files:

As a result, there is no need to change the end fixity of the top of the shear wall, as long as the loads have been properly distributed. Using the cantilever configuration for a multi-storey shear wall , it can be designed element-by-element, accurately designing each storey for the same shear and moment profile as would be used if the full multi-storey shear wall were designed at once.

Only by using the default cantilever fixity selection can an individual storey be adequately modeled without having to apply additional loads to cancel out the effect from a fixed top rotational end condition.

Summary

To quickly summarize, there are three main things to consider when designing a multi-storey shear wall using MASS:

1. Load Distribution: all loads not applied directly to the storey being considered must have their effects included. In particular, the accumulation of axial loads, lateral loads, and overturning moments due to loads applied from storeys above.
2. Total Height: To avoid being penalized for squat shear wall moment arm reductions, be sure to change the total height in order to accurately reflect the full height of the wall.
3. End Fixity: While it may at first seem reasonable to factor in the rotational stiffness from storeys above by changing the top fixity to Fixed (R), it will not result in a moment profile that accurately reflects the moments experienced by the storey in question. The default cantilever selection with properly distributed overturning moments is a more appropriate selection.

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

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.

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)

The CSA S304-14 divides masonry wall design into two separate chapters depending on whether or not the wall is reinforced. Chapter 7 and chapter 10 govern the design of unreinforced walls and reinforced walls respectively. Since steel cannot be used in compression without being laterally tied to prevent buckling, it is ignored for all design calculations which opens up a “grey” area. Walls can be vertically reinforced with the steel doing nothing from a capacity and moment resisting perspective if the bars are not in tension. It is these cases where the steel is ignored and the wall is designed as if it were unreinforced.

How to tell when a wall is designed with the reinforcement ignored

For a bar to be included, it must be further away than the neutral axis from the extreme compression edge of a wall and therefore in tension. Since the neutral axis location is a function of axial load (and the area of masonry required for the compression block to equal the axial load plus tensile force in the steel), there is a break even point where any marginal increase in axial load shifts the neutral axis beyond the depth of reinforcement. MASS solves for this point where the steel is no longer in tension and saves the corresponding axial loads and moment as Mtension and Ptension. For example, bars placed in the middle of a 20cm unit (thickness of 190mm) are 95mm away from the compression edge. Axial loads that result in a neutral axis, or c, location of 95mm or higher ignore the effects of steel in the design.

No. 15 bars placed at 1200mm in a partially grouted 20cm, 15MPa unit

Conversely, axial loads resulting in a c value that is less than d result in designs which include the added effects of reinforcement.

Skill testing question

Is it possible to have a wall that both ignores and includes the effects of reinforcement at the same time but for different load cases?

Where to check this using MASS

This can be checked in MASS in two places. The first is at the bottom of the Simplified Moment Results, where there a table showing how MASS arrives at a total factored moment for each load case. The Simplified Moment Results table corresponds to the example shown in the interaction diagrams above.

All load cases that result in a neutral axis location less than d (95mm in this case) use the reinforcement in tension. From looking at the table above, reinforced analysis is used for load cases 1, 3, 7, and 9.

The other place to find this information in MASS is on the actual interaction diagram drawing. Each load case can be clicked on to reveal the following information:

• M_f,p – Primary factored moment (kN*m)
• M_f,tot – Total factored moment (kN*m)
• M_r – Moment resistance (kN*m)
• P_f – Factored axial load (kN)
• c – Neutral axis location (mm)

Load combination 7 selected displaying corresponding summary information.

“Am I benefiting by adding steel to this wall?”

While a design may be designed as reinforced, where the steel is in tension and adds to a wall’s moment resistance, that does not mean that the steel is needed. Looking at the interaction diagram above, and where each load combinations lies to the region of the wall can offer insight into how the wall is behaving and which mechanism governs its failure at ultimate conditions.

Cracking restrictions based on limiting eccentricity of an unreinforced wall with the envelope curve of a reinforced wall.

The main benefit of vertical steel to the moment capacity of a wall is in the blue region of the figure above, where otherwise the wall would not be permitted to crack and rely on the tensile strength of masonry. Generally, load combinations with high lateral loads and lower axial loads fall within that region and benefit from the added steel. The example used in this post highlights an instance where the lateral loading is relatively small (Ex. low net internal wind pressure) and the reinforcement is not needed to satisfy the wall’s capacity requirements.

As written about in another post, there can be other reasons why MASS is adding reinforcement to a wall. However, it should be noted that by starting with the default masonry unit and reinforcement selections, MASS will first return a successful unreinforced design and only after the disabling the unreinforced selections will MASS add “unnecessary” steel to a wall design.

There are perfectly valid reasons to add steel to the wall design in this example that are outside the scope of a MASS wall module such as when the wall is acting in a system with other reinforced walls. The important thing is that the designer fully understands why the software returns the results that it does and what the reasons are for doing so.

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.

¹ Conjoint Professor, Centre for Infrastructure Performance and Reliability, School of Engineering, The University of Newcastle, Newcastle, Australia, spl@bigpond.net.au

ABSTRACT

The flexural design of sections of masonry spanning vertically with simple supports at top and bottom is usually carried out using simple bending theory and the flexural tensile strength of the material. Simple masonry walls behave in a brittle manner and the flexural strength is known to be highly variable. Simple stochastic analysis can be used to provide an improved behaviour model. The principles of this analysis are outlined. A database of wall test results gathered from around the world is used to examine the ‘model error’ in the simple bending model and shows that there is clear evidence of a size effect, resulting in longer and higher walls having lower strength. It is shown that adjustment of predicted wall strength by the simple stochastic analysis can greatly reduce this bias, producing more consistent estimates of wall strength across a range of lengths and heights.

KEYWORDS: unreinforced masonry; lateral loading; walls; stochastic analysis; design; size effects

C1-4