Masonry Wall Panel - Modeling

The masonry wall panel element allows you to easily model, analyze and design masonry walls for in plane and out of plane loads. Here we will explain the masonry specific inputs and procedures for modeling. For general wall panel information, see the Wall Panels topic. For information on masonry design rules, see the Masonry Wall - Design Rules (this is where you can define block thickness and self-weight). For masonry calculation considerations and code references, see the Masonry Wall - Design topic. For masonry wall results interpretation, see the Masonry Wall Results topic.

Note:

• All code references in this topic refer to the TMS 402-16 specification unless noted otherwise.

Masonry Wall Input

The Wall Panel Editor gives some specific information and options for modeling/analysis of masonry walls.

Masonry View Controls 

Masonry Wall Panels will have the following view controls:

Toggle Region Display allows you to turn the display of regions on or off.

Toggle Lintel Display allows you to turn the display of lintels on or off.

Toggle Out of Plane Reinforcement allows you to turn the display of out of plane reinforcement on or off after you have solved your model.

Toggle In Plane Reinforcement allows you to turn the display of in plane reinforcement on or off after you have solved your model.

Creating Openings in Masonry with Lintels

Within the Wall Panel Editor, you have the option of adding rectangular openings to masonry wall panels. To draw an opening, select the Openings button and then select two nodes or grid intersections which make up the two diagonal corners of your opening. When an opening is drawn a lintel is automatically created above the opening. To view or edit the properties of a masonry lintel, double-click inside the boundary of the drawn opening. This will bring up the Editing Properties window for that particular lintel.

This window will show the design options set in the Wall Design Rules - Lintel spreadsheet to design/analyze your lintel. If you have multiple lintels in a wall and want a specific design that differs from the other lintels, then you canchoose the Custom option. When using the custom option, the program will now use all of the information set in the Lintel Editor and will disregard any information given by the design rule.

Here we will walk through the different input options available for designing/analyzing lintels:

Depth - This is the depth of your lintel.

Bearing Distance - This is the bearing length at either end of the lintel. This is used to calculate the effective length of the lintel.

Bar Size - This is the reinforcement size you wish to use for your main reinforcing in the lintel.

Bars Per Layer - This is the number of bars you wish to have in a given layer of reinforcement. There is also an option to have the this value optimized based on geometry of the section and also the number of layers that you have defined.

Number of Rebar Layers - This is an option if you need multiple layers of reinforcement in the lintel.

c/c Spacing of Layers - This is the distance between layers (if there is more than one).

Centroidal Distance of lowest layer from the Bottom - This value is used to calculate the "d" value for the lintel.

Stirrup Size - This is the size of stirrup that will be added to the lintel if required.

Note:

• When inputting bar sizes for your lintels, the program will not allow you to place reinforcement that will not actually fit into the lintel because of width constraints. We use the actual dimensions of the block, the face-shell thickness for the given block chosen and use a 1/2" clear cover between reinforcement and the block per section 6.1.3.5.

Masonry Regions

Within the Wall Panel Editor, you have the option of creating rectangular regions within the masonry wall panel. Regions are used to define reinforcement in different parts of the wall. Each region will be assigned a uniform reinforcement, which may be different than the reinforcement in other parts of the same wall.

If no regions have been drawn on a wall then they will be automatically generated when a solution is performed. To automatically generate regions prior to running a solution, click the Generate Wall Regions Automatically button

To manually draw regions, select the Create New Regions button and use your cursor to select two nodes or grid intersections which make up the diagonal corners of the region. To exit this tool right-click your mouse.

To view or edit the properties of a masonry region, double-click inside the boundary of the drawn region. This will bring up the Editing Properties window for that particular region.

The information is populated from the Wall Design Rules spreadsheet for masonry. For more information see the Masonry Wall - Design Rules spreadsheet on setting this up.

In most cases this Region Editor would only be used as a viewer. If, however, you want to change the reinforcement for a region within the wall to make it different than the Wall Design Rules, you can use the Custom option. When using the custom option the program will now use all of the information set in the Region Editor and will disregard any information given by the design rule.

Note:

• For models created with version 5.1.1 or earlier ALL regions will come in set to Custom, bringing over the information exactly as it comes from the existing model. For all newly created models in version 6 or later the regions will default to the wall design rule.

Within this dialog you can specify the properties which will be used for the design of the region. The program can optimize the bar spacing and the boundary zone width based on code checks. The block size, reinforcing strength and the method of self-weight calculation are defined in the Design Rules under the Masonry Wall tab.

Note:

The program designs regions separately for out-of-plane and in-plane forces, thus the Region Editor is divided into different parts.

Here we will walk through the different input options available for designing/analyzing regions:

Transfer - This is an option as to whether or not you want this region to transfer Out of Plane and In Plane Loads. If you check these transfer options, the program will dump those loads above and below an opening into the adjacent regions for design.

Note:

• These transfer options are only available when you have defined a region above or below an opening.
• If you do not choose to check these transfer options you will see design results for regions above and below openings.

Axial /Out-of-Plane - Allows you to define properties of a region based on out-of-plane/axial forces.

• Block Grouting - Allows you to define how you want your wall grouted. If you choose "Partially Grouted" the program will optimize the grout spacing with the Bar/Grout Spacing
• Reinforced - Gives the option of designing the wall as reinforced or unreinforced.
• Bar/Grout Spacing - This allows you to define the bar/grout spacing. If you have the "Optimize" box checked, the program will optimize the reinforcement spacing based on code checks.
• Bar Size - This is the main vertical bar size that will be used in design.
• Bar Placement - This defines how you want to lay out the reinforcement in your region. Each Face will put reinforcement on both faces of a given cell. Staggered alternates the bars to either face of wall region.
• Note:
  • When using the staggered option you are selecting to space the bars at each face at double the bar/grout spacing defined above. For example, if you have a staggered spacing at 24" oc you have a bar on the outside face at 48" oc and a bar on the inside face at 48" oc. These bars are staggered, thus you have grout filled cores at 24" oc.
• Mortar Type - Allows you to specify the type of mortar to design for.
• Cement Type - Allows you to specify the type of cement to design for.

In-Plane - Allows you to define properties of a region based on in-plane forces.

• Vertical Bar Size - Allows you to define vertical bar size for the boundary zones.
• Bars Per Cell - Allows you to define one or two bars per cell.
• Boundary Zone Width - The user must define a boundary zone width but RISA will optimize the width if the "Optimize" box is checked.
  • Note: If you have the optimize checkbox selected, the program will optimize the boundary zone width based on code checks.
• Horizontal Bar Size - Allows you to define horizontal bar size to be used if horizontal reinforcing is required.
• Multiply Shear by 1.5 - This is an option that may be required in high seismic zones. This option is available per section 7.3.2.6.1.2.

Masonry Wall Optimization

The program will optimize masonry walls and lintels based on the required demand forces. The program can optimize:

• Vertical bar/grout spacing for out of plane design.
• Reinforcement bars for lintel flexural design.

Lintels

For masonry lintels you must input the dimensions, bar size and number of layers of bars for the lintel, but are given the option of optimizing how many bars are in a given layer. If you provide a max/min number of bars in the Wall Design Rules - Masonry Lintel tab then the program will optimize the number of bars in a layer.

Lintel Reinforcement Placement Check

The program will do a check to see that the reinforcement in the lintel will fit properly. The available width for reinforcing in the lintel is based on the width of block, thickness of grout between the block and the reinforcement, and it assumes there will be a double-leg stirrup.

where

• t_grout = 0.5 in (per Section 6.1.3.5 of ACI 530-13; the program assumes coarse grout)
• dbstirrup = diameter of stirrup (from the Wall Design Rules - Masonry Lintel tab)

Note that we use a minimum bar spacing equal to the minimum of either d_b or 1".

Regions

For masonry regions, there is one option for optimizing. For out of plane design, the program will optimize the spacing of bars for strength (not deflection) considerations of the wall .

Limitations

• Openings and regions must be input only in RISAFloor if you are using RISA-3D and RISAFloor in tandem.
• For sloped walls due to sloping floors, openings and regions can not be defined in the upper triangular area of the wall panel. These openings are not supported at this time. This will be addressed in a future version.
• For areas of masonry wall panels that are not defined as a region, the stiffness of the wall is assumed to be that of an ungrouted masonry wall and the weight of the wall is assumed to be that of a fully grouted wall.
• You can only define regions that are full height from floor to floor. If you have a panel that is multiple floors high, you can span your regions to multiple floors or single floors.
• Masonry has specific requirements regarding the spreading out of concentrated loads at certain angles and for certain depths (Section 5.1.3). These provisions are not considered in RISA, as the finite element mesh stiffness is what determines load path. See the Wall Panels - Load Attribution topic for more information.