ProtaStructure : Working with Walls

Working with Walls

Defining a New Wall

Before inserting a wall member its reference axes must be defined.  

Walls are defined by two axis intersection points (insertion points)  defining the start "I" and end "J" of the member. Hence for wall, 3 axes are needed for create the 2 insertion points. 
To define a new wall member:
  1. Display the storey level in the drawing area which will contain the top of the wall.
  2. Press the “Wall” button located in the "Modelling" ribbon > Wall "Properties" dialog will appear. 
  3. Edit the fields in the "Wall Properties" form. For example, enter the Wall Label in the "Label" field (max. 11 characters) to modify the section dimensions and eccentricities.
  4. To insert the wall, pick two axes intersections to insert the wall, in view drawing area, or the 3D view. 
Labels of the axes that reference the “I” and “J” ends of the wall will be displayed in “Top ” and “Bot ” fields  on “Wall Properties ” form.
Identical axis intersections will be written in these fields when the wall is first defined. In this case wall will be placed vertically between the storey levels.

Wall Shortcut Menu

You can access the most often used command options for the wall by first selecting a wall or multiple walls : 
  1. The Wall ribbon will appear with at the top containing all relevant commands
  2. Alternatively, right-click anywhere in the modelling view will also expose the same shortcut menu. 
  3. Command functions for single wall selection includes “Polyline Wall Editor”, “Section Design”, “Elevation Drawing” and “Punching Check”. These options will be omitted from the shortcut menu when multiple walls are selected. 
  4. “Delete”, “Mirror Elements” and “Properties” options are default options in shortcut menus for all member types. 

Editing an Existing Wall

In order to edit an existing wall:

  1. Select an existing wall.
  2. Right-click and select “Properties” menu option. 
  3. Alternatively, double left-click on a wall to bring out the Properties menu. 
  4. Modify the fields such as "b" and "e” in the "Wall Properties" form.
  5. Press the "Update" button in the “Properties” form or Right-click and select “Update” option in the Shortcut Menu.

Right-clicking on any one of the “b”, “e”, “Ext. I”, or “Ext. J” fields will load a list of commonly used values that may facilitate data entry.

You can repeat this process on as many members as you wish. One member at a time can be edited by this method. If you want to update several columns at once, you can use "Wall Table" in the "Member" menu. The “Wall Table” form can also be reached from the “Member Tables” option in the shortcut menu.

Editing Multiple Walls

If you want to update several walls at once, you can :
  1. Multiple select walls to be edit > Right-Click >  Properties
  2. Wall Table dialog will be shown where you can display & edit properties in a group
Alternatively, with no walls selected :
  1. Right-Click anywhere in the modelling view
  2. Select "Member Tables"  > Wall Table
  3. Wall Table will show all walls in the active Storey 


Refer to this article for details :  Display and Edit Member Properties

Wall Properties

"Wall Properties" will be loaded when the "Wall" option in the "Modelling" menu is selected.
A new wall can be defined by arranging the fields in the form and then by dragging two axes intersections in the plan window. 

The “Wall Properties” form can also be accessed after selecting an existing wall and then by right-clicking and choosing the “Properties” option in the shortcut menu.

You can select a wall member by using one of the “Member Selection” methods described previously.

When the “Wall Properties” form is open, right clicking a new Wall member and selecting the “Select and Load Properties” option in the shortcut menu will load the properties of the new member in the same window.

The “Wall Properties” form comprises 2 pages named as “Gen” = General & "Geo" = Geometry. You can shift between pages by pressing the related tab heading.

The General tab consists of the following fields / options : 


Label

The wall label can be entered in this field. This field (after formatting) is limited to 11 characters. A text control spin button exists to the right of the label field to facilitate the creation of successive label text.

As in all member types, wall member labels will be listed in the “Structure Tree” under the related storey heading. This list can be used to select a member by label.

Repeating member labels is not permitted in a building. During the insertion of members the program will sound an alarm and a warning message will appear in the status bar if a repeating member label is detected.

Len (Length Storey)  

Enter the number of storeys the wall spans. Generally, every wall spans one storey in building type structures. If the wall span more than one storey, the number of storeys can be defined in this field.

For example, if a wall in the 4th storey spans to the 2nd storey top level, this means that the wall will exist along 4th and 3rd storeys. Therefore, "2" must appear in the "Len (Storey)" field.

Wall with "Len > 1" will be rendered in grey color in the lower storey(s) where the wall is spanning. 
Hence, if "Len > 1" is used, do not create a new wall at the lower storey(s) where the above wall is already spanning, overwise they will be overlapping.  
Wall Thickness (b)

"b" is the thickness of the wall, which is the section dimension along its minor direction.

There is minimum limit to the ratio of the dimension (length/b) of walls according to selected code of practice. If the minimum ratio is not satisfied, it should be modelled as a column instead of a short wall.
For example, if British Code is selected, wall whose length that is less 4 times its thickness (b) would be designed as column, as per BS8110-1997 (Cl.1.3.4.1).
Wall Eccentricity (e)

The eccentricity of the wall along its minor direction is defined by the field "e" measured as a distance between the insertion axis and the centreline of wall having a left I-end and a right J-end.

"e" value cannot be greater than section width/2 or smaller than the –width/2.


Wall Insertion Options Button

A set of wall insertion option buttons are provided for facilitating the definition of “e” field.


 Insertion Options
After setting the dimensions of a wall, you can easily set the column eccentricities by pressing the “Wall Insertion Options” button. After pressing this button a window will appear displaying “Eccentricity Option Buttons”.

Choosing one of the options available in the “Eccentricity Option Buttons” will automatically redefine the “e” field.

The "Update" button must be pressed to update the selected column with the new eccentricity values.

It should be noted that the eccentricities of the wall defined here will not modify the location of the actual analytical frame member used in the analysis model. The frame member will be located on the insertion point of the wall.

Alternatively, you can control the “e” value using the direction keys of your keyboard.

In order to modify the eccentricity : 
  1. Select a wall and load the “Properties” dialog. 
  2. When you press left or right keys, the “e” property will be modified and the wall is displaced.
  3. The eccentricity step value can be set using the “Member Section Eccentricity Step” value in Settings Center > ProtaStructure Environment 
Alternatively, without bringing out the "Properties" dialog, use keyboard arrow keys directly to move the wall. 

Wall Extensions (I, J)

These fields define the extension dimensions of the wall from I and J axis intersections.
I-Extension is measured from "I" Reference Point to the edge at left and J-Extension is measured from "J" Reference Point to the edge at right along the major direction of the wall.
These values should be greater than or equal to zero but less than wall thickness. The reason is the extension cannot support any other members such as beams; it is only meant for presentation. If the wall is intended to be longer, create a new axis for correct insertion point. 

Insertion Axes

All structural members are inserted based on axis intersections as an insertion reference. At least two axes must intersect at every insertion point.

The simplest method for defining the insertion axes of wall elements is selecting two axes intersections in the drawing area. Left click to select the first point and then left click to select the second point.

Following rules apply for the insertion of Walls:

  1. Insertion points can be clicked in any preferred direction along the insertion axis.
  2. The defined "I" and J" points will be swapped automatically when necessary based on the lower left point priority method.
  3. At least one common axis must exist among the two intersections. This common axis is termed as the "Insertion Axis" of the Wall.

Labels of the axes that reference the “I” and “J” ends of the wall will be displayed in “Top” and “Bot” fields in the “Wall Properties” form. Identical axis intersections will be written in these fields when the wall is first defined. In this case wall will be placed vertically between the storey levels. 

The "Top" insertion axes cannot be changed. 

A vertical wall can be changed to inclined or slanting by changing the bottom insertion axis : 

  1. Click "Bottom Insertion Point icon  
  2. Pick the new longitudinal axis line on plan 
  3. Click "Update" & the wall will be inclined  (Review 3D view)
For illustration, you can refer to similar article for slanting column :  How to model slanting / inclined column.

Wall End-Condition Options (Fix / Hinge)


Wall End-Condition

You can use the "Wall End-Condition (Fixed/Hinged)" button to release moments of top, bottom or both ends to assume pinned-end condition.

By successively pressing this button you can follow which end becomes hinged.
When one of the ends of a wall is hinged, the moments are released in two orthogonal directions.

Click "Update" icon to take effect

Any hinge setting will only apply for "Mid-Pier" wall analysis type and not "FE Shell". "FE Shell" wall will always fixed at top and bottom nodes.

Wall Section Manager

Wall Section Manager and Material can be accessed in “Edit Section / Material” by either : 
  1. Click "Section Manager" icon   in wall Properties menu   
  2. Select a wall > Right-Click > select "Edit Section / Material"
The Section Manager is as shown below.


The dialog window comprised of “General”, & “Properties”  tabs. 

General tab

Section dimensions input fields will be shown. 

Under "Materials",  material properties (concrete and reinforcing steel grade) defined in "Materials" dialog will be assigned as "Default" to the wall element unless otherwise specified :  
  1. To change from default, you can click on [Default] to change the material. 
  2. However, we advise you do not change the default as material are best set in master Materials dialog (in "Building Setout" ribbon). This is more efficient that trying to set each wall material one by one. 

Properties tab 

The section properties tab shows all the auto-calculated section properties of the wall. 

"I1" is the moment of inertia along direction-1 axis (about direction-2 axis) and "I2" is the moment of inertia along direction-2 axis (about direction-1 axis) of the wall.

“A” is the gross area of the section.

“Shear Area” is used for the calculation of shear deformations and is calculated automatically as "5/6" times the axial area of the section.


You can override the automatically calculated properties by either : 
  1. Under Factors, input the ratio; example 1 = 100%, 0.5 = 50%
  2. Check "Edit Manually" & manually enter values. Be warned that this will de-link the auto-calculation of section properties, e.g. when column sizes change. 

Wall Geometry tab

In wall properties, Geometry tab consist of the following : 

Plane (Top) & (Bot)

This field will be state the plane number that is attached to this wall. The top & bottom node will automatically follow that of the attached plane. 
To detach it from the plane you can click the icon .
For information on plane, refer : Working with Planes

del z (Top) & (Bot)

By default, when wall is created, it automatically follows the storey height. 
Example if you model the wall at ST01 :
  1. The top I & J nodes of the wall is the same as the top of the storey ST01 level - i.e.  del z (Top) = 0mm
  2. The bottom I & J nodes is the same as the top of the below storey ST00 level  - i.e. del z (Bot) = 0mm. 


You can manually change the top and bottom nodes of the wall by modifying del z values, example :  
  1. Del z (I & J) (Top) : Positive value will elongate the wall upwards, vice versa
  2. Del z (I & J) (Bot) : Positive value will shorten the wall upwards, vice versa. 

If "Plane" is used to define the wall, the delta z value will automatically be calculated based on plane elevation & these fields will be deactivated. 

Support Types 

You can review or change the Support Type for the bottom Node of a column : 

  1. [Default]  - For all columns & walls created in ST01, a default fixed support (restrains in all six degree of freedom (DOF) will always be created & assigned automatically, as ST01 is the ground floor
  2. For all columns & walls created in ST02 and above, the [Default] option means it is free to move (not restrained) and will automatically be supported by elements modelled below it. 
  3. [None] means the column or wall be free to move in 3D. This option should not be used, as it ignore any elements modelled at the column bottom node. 
  4. If there are other supported types created via Support Type function - they will be listed & selectable. 

Transfer Member 

If this wall is discontinuous, i.e. it is a transfer wall then this option must be checked.
Checking this option will ensure the transfer wall can be correctly analyzed and designed. 

Wall Model Type

ProtaStructure provides different options for the analytical model of wall.
You can control modelling options globally for all the walls in the system by going “Building Analysis” > Model Options > “ShearWall Model”.
You can override the global model option by selecting a model type other than “Default ” from the dropdown list in the “Wall Model Type” field.
By this way, you can use different wall models for each separate wall.
  1. Mid-Pier Model [Default]
This utilizes a single column (mid-pier) at the center of the wall with rigid beam at the top of the wall. 
  1. Rigid beam is auto-created to support other members.
  2. Deflection is constant along the entire rigid beam length.
  3. Analysis time is efficient. 
  4. Suitable for normal shear walls that starts from foundation to superstructure. 
  1. Finite Elements Shell Model
    Entire wall is meshed as shell elements. 

  1. Variation of stresses along the wall length & height can be captured.
  2. Deflection can be different along the wall length.
  3. Suitable & more accurate for transfer wall supported by transfer beam. Example refer to : How to model a Transfer Beam
  4. Suggested mesh size is approximated storey height divided by 4. 
  5. Merged shear walls are automatically meshed.
  1. Basement Wall (Meshed)
    1. This is specifically for seismic analysis & design of basement walls; where special consideration of the participation of the basements mass in the dynamic analysis is varied. 
    2. These results are run concurrently & combined in accordance with the relevant seismic code. 
  1. Retrofit Wall (Shell / Mid-Pier)
  1. A retrofit shear wall is similar to a RC regular shear wall, except that additional “Anchor (dowel bar)” are added for seismic strengthening.
  2. There will be an additional “Anchor (dowel bar) Design” button in the Interactive Column Design Interface, which can be designed for retrofit.
  3. These walls are recognized by ProtaDetail & special dowel detailing can be produced (as shown below in a shear wall elevation detail).


Drop / Slab Patch Panel

In Flat Slab type floor systems (no beams), a drop panel can be inserted on top of the wall in order to increase punching resistance. 

Please do not insert a drop panel if there are beams framing into the wall or column .
The sole purpose of drop panel is to increase punching shear resistance for flat slab. 
There will analysis & design conflict where beams, being stiffer, will inherently absorb most of the shear forces; rendering the drop panel redundant. 
Slab patch panels can be created in order to design additional rebars at the wall support regions. 

A Wall Drop or a Patch Panel can be independently assigned to wall. In other words, column wall dimensions can be different than patch panels.



To insert drop panel, check "Drop Layout" : 


  1. Dimensions and Eccentricities of the Drop Panel can be adjusted using “b1”, “b2”, “e1” and “e2” data fields. Definition of these parameters are identical with wall dimension and eccentricity parameters. 
  2. In order to locate the drop panel just to center the wall, press “Center” button . “e1” and “e2” values will automatically be determined according to the wall size.
  3. "H" field is the total depth of the Drop Panel, measured from top of the flat slab. Hence, the value must be more than the slab thickness.
To insert Patch panel, check "Patch Layout" : 
  1. Dimensions and Eccentricities of the Drop Panel can be adjusted using “b1”, “b2”, “e1” and “e2” data fields
  2. In order to locate the drop panel just to center the wall, press “Center” button . “e1” and “e2” values will automatically be determined according to the wall size.
Kindly read this article for further details on flat slab design using drop & slab patch panels :  Flat Slab and Raft Design with Slab Patch Panels

Update Button

Whenever you make new specifications in one of the fields in “Wall Properties” form for an existing column member, press the “Update” button in order to display the changes in the plan window.

Close Button

Pressing the “Close” button will close the “Wall Properties” form and return back to “Select Mode”.

Wall Openings

Multiple openings  can be defined for shear walls / core walls using "Wall Opening Editor". Rectangular or square opening can be accurately positioned to consider door opening for example. 

Steps:-

  1. Select a shearwall, right-click and select "Wall Opening Editor".
  2. "Wall Opening Editor" dialog will appear.
  3. Click Add/ Delete buttons to insert/ delete openings. 
  4. User can select the openings on the drawing or on the table. 
  5. User can change Width, Height, and Position of the openings on the table. 

Before analysis, ensure that the wall model is set to FE Shell Model : 

  • Select a wall > Right-click and select Properties > Geo tab > Wall Model Type > Pick FE Shell Model (only this wall will be meshed)  OR 
  • Go to Building Analysis menu > Models Options > ShearWall Model > check Finite Element Shell Model (all walls in the model will be meshed)

Unlike infill wall openings, the shear wall openings cannot be closer than 200mm to each other or to the shear wall edges to ensure proper meshing. This is automatically adjusted in the meshing of the wall during analysis. 



The Scope and Limitation of Shear Wall with Opening:
  1. Wall opening will be only considered when using FE shell wall. (Change in Wall Properties > "Geo" tab)
  2. Design of wall will not taken into account of wall opening. Thus, wall with opening will be designed as normal wall.
  3. Reduction of section area due to wall openings will NOT be considered in the design of the walls and only consider in analysis when meshing the walls. The analysis results of localized and distributed forces that are experienced by the walls will be represented as contours.
  4. In elevation detail, trimmer bars will be provided as good practice but these are not designed for specifically to any code of practice.
    As such, currently this function is more useful for small opening such as window opening. 

Merged Shear Walls / Core Walls

Multiple shear wall panels can be selected and merged into a single core wall. This allows the shear wall to be analyzed, designed and detailed as single integrated entity, increasing efficiency & productivity.  The steps are :  

  1. Multiple select  connecting shearwalls
  2. At the top wall ribbon select "Merge Vertical Members" 
  3. Alternatively, Right-click > Select "Merge Vertical Members" 
  4. Separate wall panels will be merged into single core wall
  5. If there are any openings on panels, they will be reflected on the core wall as well. 
  6. The label of the longest wall will be used. 
  7. All the panels are also kept in the wall records so walls can be unmerged by choosing "Unmerge Vertical Members"
Resultant design forces are automatically calculated with respect to geometric center of the merged core wall.  
Core-wall must be unmerged before assigning any openings, span loads or nodal loads on it. 
To unmerge the walls :  Select the merged wall > Right-click and select "Unmerge Vertical Members". 

We recommended for initial or preliminary stage, shearwalls should not be merged.  The reasons are :

  1. For unmerged single panel walls, the wall design is fully automated. The design automatically selects the size, number and position of bars.
  2. For merged walls, the design is partially automated. The rebars numbers & position must be manually defined first. The design only chooses the rebar sizes to achieve pass status. 
    1. Refer this article on how to define rebars for merged walls : Define Merged Wall/Irregular column Reinforcement in Polyline Column Editor
  3. If single panel walls (unmerged) fails in design, it is unlikely that it will pass when merged, as the design forces are essentially the same. 
  4. As such, it's logical to model & analyze shearwalls as separate panels first (i.e. unmerged) > design the walls and ensure all the walls passes.
  5. Then if desired, merge the walls & define bars according to the initial design and proceed to re-design the walls.  

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