Peak Zones

The Peak region reinforcement is intended to provide a general reinforcement in the T1 and T2 ( or B1 and B2) layers of an area of slab to cover the general reinforcement design within a region of peak design forces, such as occur over the head of columns or beneath transfer columns. Peak regions are be defined to apply to points representing the intersection of slabs and vertical 1D elements such as column/slab interfaces (column above, below or both) or at the end points of walls. Peak regions can occur at the boundaries of basic rebar regions and even at the interface of different FE surfaces.

On first entering the Slab Design Module, the default layout of the Peak Zone is as shown below.

The left hand pane displays the design calculations. The central pane displays the graphics view of the model. The graphics windows can be controlled by the menus as in Masterframe. The right hand pane contains the controls for adding Peak zone, defining the design parameters for the Peak zones, carrying out the autodesign and displaying a range of results to assist in investigating the design.

Basic Controls - Adding, Copying and Deleting Peak Zones

The basic controls for adding, copying, deleting and selecting peak regions are the icons in the Basic Reinforcement Sets area. These icons are:

 - Add a new Basic Region

 - Copy a region (automatically adds a new region with the same settings as the copied Basic Rebar)

 - Delete a region

 - Select all regions

 - Invert current selection

 - List visible items only (lists only those basic regions currently displayed in the graphics window

Adding Peak Zones

A new Peak Zone is added by first clicking on the  icon. This will add a new item to the list of peak zones and add the default properties to the property panel. Basic calculation pane will also display the default information. The layout of the screen is shown below.

The properties for a peak zone design can be set before assigning it to an FE surface or drawn region, or, alternatively, the peak zone can be created first and the design parameters set afterwards. Changes in the design output are dynamic so the calculation output will automatically update to reflect any changes made in the design parameters. When a peak zone is added, the graphics window will update to display the position of the peak zone and the shear force diagram around the valid portion of the peak perimeter.

By using the  icon, peak zone designs can be added to specific locations within in the model. By using the

Peak Zone Properties

The design parameters of the Peak Zones are defined in the design parameters input area. This is the area below the Peak Zone names area. The default layout is shown below.

To navigate through the inputs, hover the mouse over the area and use the mouse wheel to scroll up and down.

The Peak Zones properties area contains input to control how the peak zones are defined, whether the design is to be automatic or manual, definitions for the reinforcement placement relative to the FE surface local axes definitions of the reinforcement in the top and bottom layers and controls for how the design forces are derived.

General

The General input allows controls the basic design parameters of a peak zone as well as providing controls over the extend of the peak zone and the ability to define which surface the peak zone belongs to, for use in cases where the peak zone would cross the boundary between multiple FE surfaces. The General Region also provides controls over the arrangement of the reinforcement.

Name - Each Peak zone will be named automatically and incrementally numbered. To amend the name, select the row and input the desired naming

Add or Replace Basic - defines whether or not the peak zone rebar replaces or is in addition to the basic reinforcement

No. of Zones - controls whether the peak zone is designed and detailed for a single zone covering the whole peak zone or designed and detailed as a middle half and outer quarter strips

Outer bars over full width - for use with Two zones. The outer bars can be placed either only in the outer zones or across the full width and so add to the bars of the central zone

Parent FE surface at node - sets the surface the peak zone is assigned to for use with peak zones at or adjacent to FE surface boundaries

Crop to Parent Slab - allows the peak zone to be cropped to lie only within the parent slab and so not cross any slab boundaries

Design Force

The Design Force provides controls to define how the forces in the selected peak region are averaged for the purposes of the reinforcement design. The required option is selected from the Design Force drop down by selecting the row and then using the drop down to select the required option. The default selection is to average over the full width. The default layout is shown below.

The options available are:

Average over full width - averages the forces over the full width of the peak zone or middle and outer strips if Two Zone design is selected

Average 0.5 full width - for use with a single zone design to limit the width over which force averaging is done

Average - limit width - user input to define the averaging width per zone in metres

Average - limit effective depth multiple - define the width for averaging per zone in terms of multiples of the effective depth

The aim of the averaging width is to prevent the case of specifying wide zones and so averaging the forces over a large width which may lead to over reduction of the design forces.

Auto Design and Bar Arrangement

Auto design can be turned on or off for each Peak Zone. This is defined for a Peak Zone by highlighting the Auto Design row and selecting the required option from the drop down. With no auto design, the Peak Zone reinforcement is fully determined by the user in the Bars input area. With auto design turned on, then the software will carry out an auto design and determine the reinforcement required to satisfy the design requirements of the basic region. In addition to designing the reinforcement, the size of the peak zone can be designed by the software or input manually by the user.

When the auto design is activated for a Peak zone by setting the Auto Design row to Auto Design Bars, the input area expands as shown below.

The bar sizes and spacings are defined in the Defaults area. However, by adding bar and spacings dimensions in the Bars Sizes and Bar Spacings row, it is possible to further control the allowed bar arrangement and sizes for use with the auto design. Multiple bar sizes and.or spacings can be input by separating the required dimensions, separated by commas.

The Auto Design options are selected by highlighting the Bar Arrangement row and selecting the required options. These are:

Fixed bars (No auto design) - peak zone reinforcement is specified by the user with no auto design for the reinforcement. No bar size of spacings input appear with this option

Auto design bars (no fixed) - reinforcement design will be done by the software. Reinforcement size and spacings will be based on Defaults setup but can be refined by Bar sizes and Bar Spacings inputs

Fixed + Auto Design additional - for use with Replaces basic rebar option. Fixed bars are specified and if not sufficient the auto design will calculate additional reinforcement required

Auto Size Zone will size the extent of the Peak Zone as part of the auto design. The peak zone size can be amended or over written using the inputs in the Geometry area.

Bars

The Bars input region provides inputs to specify and control the reinforcement within each peak zone. Unlike the Basic Region inputs, each Peak Zone is intended to only have bars in either the top or bottom of the slab and so there is only a single input area per peak zone.

The default layout of the Bars area is shown below.

Top or Bottom - controls the placement of the reinforcement in the peak zone

Set T1/B1 layer - defines which direction the T1 or B1 (depending on placement of bars) bars run.

Cover - defines the cover to the reinforcement. An input of 0 uses the default setting. See Default area

Bars Dir 1 (x) - displays the currently defined Dir 1 bars

Bars Dir 2 (y) - displays the currently defined Dir 2 bars

Bars Dir 1 (x) Zone 2 (Outer) - displays the currently defined Dir 1 bars in the outer zone

Bars Dir 2 (y) - displays the currently defined Dir 2 bars in the outer zone

If the Peak Zone is set to use One Zone for the design, then the Zone 2 inputs will not appear.

The reinforcement bars can be input or amended by expanding each row in turn. This is done by clicking on the arrow to the left of the required row. The expanded Bars Dir 1 row is shown below.

Lock auto design bars - locks the current auto design bars so that subsequent auto designs will not change the current defined bars

Bar φ - current bar diameter. Selecting the row gives a drop down from which the required bar diameter can be selected

Bar Spacing - displays the currently set bar spacing. Spacing can be amended by selecting the row and using the drop down to select the desired bar spacing

Geometry 

The Geometry area provides input to control the layout, orientation and overall shape of the peak zone. The layout of the Geometry area is shown below.

Align with column beta - controls whether or not the peak zone orientation is aligned with the column orientation. Select the row to pick the required alignment option

Angle (deg) - input to define the orientation of the direction 1 bars relative to the FE surface local x axis.

Shape - shows the currently selected shape of the peak. Options are asymmetrical (quadrilateral), symmetrical (rectangular) or square. The default setting is symmetrical

Half width Dir 1 (m) - the half width of the peak zone in direction 1

Half width Dir 2 (m) - the half width of the peak zone in direction 2

With Asymmetrical chosen, the number of width inputs will increase to 4, to reflect the number of inputs required to define the shape of the peak zone. Likewise, when the peak zone is set to Square, only one width input is required.

In addition to inputting the half width values in the Geometry area, the dimensions of the peak zones can be amended graphically. This is done by selecting the required peak zone in the graphics window or picking the required Peak Zone from the list, then using the mouse pointer selected the grips and holding the mouse left button, drag the grips to the required position. The effect on the peak zone size and shape will depend on whether the geometry is set to asymmetrical, symmetrical or square.

Reinforcement Auto Design

If the reinforcement in the peak zones is set to auto design and the parameters have been defined within the Auto Design area, the auto design is then carried out using the options provided within the Auto Design menu area. The layout of this area is shown below.

The Defaults area can be accessed by clicking on the  icon. This will open the Slab Design Basic Data and Defaults menu, which can also be accessed by selecting the  icon. This area allows the default parameters for design to be reviewed or defined.

The Auto Design can be carried out for individual selected Peak Zone. This is done by selecting the required basic region either graphically or from the list of Peak Zones, then selecting the  icon. To carry out an auto design for all Peak Zones, select the  icon. Finally, to carry out the auto-design for all reinforcement zones, select the  icon.

Further control over the areas the auto design is carried out for can be achieved by using the Visible Only check box. The basic functions of the autodesign modes remain the same, but they are limited to only those which are currently visible on in the graphics display. For large models, the auto design can take a significant amount of time to complete and it may be desirable to limit the amount of the model for which the auto design is carried out at any one time by using the Masterframe viewing tools to carry out the auto design for parts of the model.

The Scan for failures option will scan all reinforcement regions and zones and identify those for which the current specified reinforcement is not satisfactory. After a scan for failures is complete. each subsequent press of the Scan icon will jump to the next region or zone for which the design fails.