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7.2 Frame Definition

7.2.1 Input Dialog

When inputting a new frame, the dialog above is presented to the designer. The data cells initially available in the top
area of the dialog provide the minimum data input required by RAPT to set up a frame. Depending on the options
selected in this area and in Structural System, different data will be requested in the lower area Structural System.
All of the data entered here can be modified once the data is accepted and the main data structure is created for the
frame.

Data Definition
Number of Spans
The number of spans (not including cantilevers) in the frame.

Cantilever Left
Check the box to nominate a left cantilever in the frame.

Cantilever Right
Check the box to nominate a right cantilever in the frame.

7.2.2 Panel Type

Select whether the Panel Type is to be an internal (there are other support lines on both sides of this support line) or
an external panel (this is the edge support line of the floor.

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Prestressed Frame
Check the box if prestressing strands or tendons of some sort are to be defined in the frame.

7.2.4.2 Building Type

Nominate the building type for the creation of the load combinations.

Loading Type
The loading type controls the settings used for the deflection limits. The options are shown below.

1. General:- Only total deflection is of interest. Nothing is being attached to the slab which will be damaged by
deflections of this magnitude so only visual and sensory limits are required.
2. Masonry Partitions: The member is supporting Masonry Partitions which many be damaged by deflection.
3. Brittle Finishes:- The member is supporting or has attached finishes which may be damaged by deflections,
e.g. glass curtain walls.
4. Vehicular/Pedestrian:- The member is carrying vehicle or pedestrian traffic.
5. Transfer:- The member is a transfer member supporting other structural elements which require special
deflection limitations. This would apply to any transfer member supporting and transferring a concrete
structure above to a different support layout below.

Structural System

The list of structural systems above is available to select the system required for this design. When a structural system
is selected different area of the Options for Structural System are made available for further input of data.

Structural Systems
The following structural systems can be selected for RAPT to create the main data file.

General System
This is the default setting and does not define an actual system. RAPT will create a default system in the data and the
designer can modify it and all of the associated data in the main input screens. No extra data is required to be input
other than that already defined.

Flat Plate
Two way slab supported by columns. No drop panels are provided. Data fields available are
1. Slab

2. Supports

3. Transverse beams (edge only)

4. Prestress if selected

5. Loadings

Flat Slab
Two way slab with drop panels supported by columns. Data fields available are
1. Slab

2. Supports

3. Transverse beams (edge only)

4. Drop panels

5. Prestress if selected

6. Loadings

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One Way Slab and Walls
One Way slab with nominal design width supported by transverse walls. Data fields available are
1. Slab

2. Supports

3. Prestress if selected

4. Loadings

One Way Slab and Beams

One Way slab with nominal design width supported by transverse beams. Data fields available are
1. Slab

2. Supports

3. Transverse beams

4. Prestress if selected

5. Loadings

One Way Slab and Bands

One Way slab with nominal design width supported by transverse band beams. Data fields available are
1. Slab

2. Supports

3. Transverse beams

4. Prestress if selected

5. Loadings

One Way Beam and Slab

One way beam supporting attached slab supported by columns. Data fields available are
1. Slab

2. Supports

3. Beams

4. Transverse beams (edge only)

5. Prestress if selected

6. Loadings

Two Way Beam and Slab

Two way beam system on the columns supporting slab panels. Data fields available are
1. Slab

2. Supports

3. Beams

4. Transverse beams

5. Prestress if selected

6. Loadings

Two Way Band and Slab

Two way band beam system on the columns supporting slab panels. Data fields available are
1. Slab

2. Supports

3. Beams

4. Transverse beams

5. Prestress if selected

6. Loadings

Structural System Data

The following data options are available for the definition of a default structural system. Not all of the options are
available in all cases, depending on the requirements of the system and other general options above that have been
selected. The options available in each case are discussed below. The frame is defined using this data in all spans.
Once the frame data file is created from this data, the designer can then make any modifications to the data to suit
the frame to be designed before running the frame and viewing the results.
In cases where two numbers can logically be the same, eg, column height above and below, column width and length,
beam width at top and bottom, RAPT will default the value of the second item to equal the first one if the user follows
the input order programmed into RAPT. The standard way to move around this dialog is to use the TAB key. This will
move through the data in a logical order.
7.2.3.1 Slab
1. Span Length:- Default span length. All spans will be set to this length. Span lengths can be modified later when the data file has been
created.

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2. Cantilever Length:- Default length of any cantilevers specified as Yes above. If no cantilever exists at an end, RAPT will automatically
extend the edge of the slab to the outside face of the column.

3. Depth:- The depth of the slab.

4. Panel Width:- The overall width of the slab panel being designed. If an external panel is selected above, RAPT will automatically
extend the external edge of the slab to the outside faces of the columns and the panel width will be dimensioned from this face.

5. Design Width:- For Nominal Width One Way Slabs Designs, the actual design width to be used.

7.2.3.2 Support
1. Height Above:- Column height above if there is one, otherwise 0.

2. Height Below:- Column height below if there is one, otherwise 0. Repeats height above by default.

3. Internal:- All columns except those at the extreme ends of the frame.

1. Width:- Column dimension across the frame if rectangular.

2. Length:- Column dimension in the direction of the frame if rectangular. Repeats width by default.
3. Diameter:- Column diameter if circular.
4. External:- External End columns. Only where there is no cantilever at an end.

1. Width:- Column dimension across the frame if rectangular. Repeats internal width by default.
2. Length:- Column dimension in the direction of the frame if rectangular. Repeats internal length by
default.
3. Diameter:- Column diameter if circular. Repeats internal diameter by default.

7.2.3.3 Beams
1. Depth:- Depth of beam from top of slab. A negative depth signifies an upturned beam still measured from the top of the slab.

2. Width at slab surface:- Width of the beam at the connection to the slab.

3. Width at beam soffit:- Width of the beam at face extreme from the slab. Repeats width at face of slab by default.

7.2.3.5 Transverse Beams

1. Internal:- All columns except those at the extreme ends of the frame.

1. Depth:- Overall depth of the transverse beams from the top of the slab.

2. Width Top:- Width of the transverse beam at the soffit of the slab.

3. Width Bottom:- Width of the transverse beam at the soffit of the transverse beam. Repeats width top by default.

2. Edge:- External End columns. Only where there is no cantilever at an end.

1. Depth:- Overall depth of the transverse beams from the top of the slab.

2. Width Top:- Width of the transverse beam at the soffit of the slab.

3. Width Bottom:- Width of the transverse beam at the soffit of the transverse beam. Repeats width top by default.

4. Edge Transverse beam:- The structural system selected will have set the transverse beam type depending on the system
chosen. However, the edge transverse beam is often different to the internal ones so the following options are provided for
the designer to over-ride the default setting for the edge transverse beams. This change can also be made later when the
data file is created. See 7.2.3.5 Input->Transverse Beams for a definition of the difference in the handling of these by RAPT.
The default setting will be the setting for the structural type selected.

1. Band

2. Beam

7.2.3.4 Drop Panels

1. Depth:- Depth of the drop panels from the top of the slab.

2. Width:- Total width of the drop panel. For external panels, this dimension is from the external edge of the concrete and so includes
the external edge distance which defaults to half of the column width.

3. Length:- Total length of internal drop panels. End drop panels will use half of this length from the centre of the column.

4. At Edge Columns:- Drop panels will not be included at external end columns unless this option is checked.

Fielders KingFlor Composite Steel Formwork (Australian Materials)/Metal Decking (Other Materials)
1. If selected, metal decking will be placed automatically on the soffit of the slab for all spans. It will span to the faces of any transverse
beams/bands, or to the centreline of wall supports. This option is only available for the three One Way Slab Structural Systems defined
above.
Note:- Metal Decking Sheets are supplied in specific widths. Normally the sheets will extend over the full width of the slab. RAPT
cannot assume an area of sheet per unit of slab width, or a fraction of a sheet width. A whole number of sheets must be defined. To
achieve this in RAPT, the Design Width for the slab must be defined as a multiple of the sheet width.
When the sheet type and sheet thickness are defined below, RAPT will automatically update the Design Width to match the next whole
number of sheets of the type selected. So, if the Design Width is 1000mm and the sheet width is 300mm, RAPT will modify the design
width to 1200mm. The cursor will be moved to the Design Width data cell whenever RAPT automatically changes this value to indicate
to the designer that the change has been made. All output results will then be the total for the new Design Width. The only situation in
which RAPT will not adjust the Design Width to suit a whole number of sheets is if the new Design Width would be greater than the
Panel Width. A warning will then be given when designing that the total sheeting width is less than the design width.

2. Sheet Type:- The List below shows all of the available Metal Decking Types defined in the Materials Properties set selected for this
run. Select the type of Metal Deck to use in all spans. The Metal Decking Type can be modified in each span in the main input. The

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Default Type selected will be the first type in the list.

3. Thickness:- The List below shows all of the available Sheet Thicknesses defined in the Materials Properties set selected for this run for
the Metal Decking Type selected. Select the Sheet Thickness of the Metal Decking Type selected to be used in all spans. The Sheet
Thickness can be modified in each span in the main input. The Default Sheet Thickness selected will be the first type in the list.

Prestress
1. Stressing Ends:-

1. Left End

2. Right End

3. Both Ends

2. Balanced Load:- Either a fraction of the self weight to be balanced can be nominated to provide a starting number of tendons and
tendon profiles.

3. Number of tendons:- Or a number of tendons can be specified. The tendons will be profiled to use maximum drape in each span
based on the default covers in 5.3 Design Standards->Prestress for the different member types.

4. Number of Tendons (Middle Strip):- If a two way slab option has been selected, a number of tendons can also be defined for the
middle strip.

Loadings
1. Dead Load:- This will be input as the Initial Dead Load.

2. Live Load:- This will be input as the live load.

Data Checking
Some of this data is mandatory and some optional. If mandatory data is left out or data input is illogical eg a beam
depth of 200mm with a slab depth of 300mm, RAPT will check the data on accepting this data with the OK button and
will move the cursor focus to the data field which is in error. The user will not be able to proceed past this dialog until
all of the data is acceptable.

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7.2.2 General Screen

Refer to 7.2.3 Frame Shape Screen Layout for discussion of the general principles of the RAPT Frame Screen layout
and to 4.5.1 General Screen Layout Principles for discussion on the general layout features of windows in RAPT.
Designer
The name of the designer in a 4.4.1 text field. This will default to the name in the 4.2.2 View->User Preferences->User
Options->Default Designer. This is used in the output report.

Project Name
The project name in a 4.4.1 text field. This is used in the output report.

Project Number
The project number in a 4.4.1 text field. This is used in the output report.

Frame Description
The project description in a 4.4.1 text field. This is used in the output report. This is also used as the default file name
when saving the data for the first time.
Design Code
The designer can select the design code that the design is to be based on from the following drop down list of the
available options.

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RAPT can design to the rules in Six Design Standards. Users can adapt any of these Standards, creating their own 5.2
Design Codes based on the rules in the basic six. RAPT will list all current codes defined in the Design Codes Directory.
The base Design Standards are
1. Australia AS3600-2009

2. Europe EUROCODE EN1992-1-1 - 2004

3. U.S.A. ACI318-2014

4. United Kingdom BS8110-97

5. South African SABS0100-1:1992

6. Singapore CP65 - 1999

7. Hong Kong Code of Practice for Structural Use of Concrete - CP2004

8. Indian Codes of Practice for Reinforced and Prestressed Concrete - IS456/IS1343

As an example of adapted Design Standards from these Base Standards, RAPT includes Singapore, UK, and Malaysian
versions of Eurocode 2 in its supplied Standards list and Materials files based on these Standards as well. These Design
Code options include the local Annex rules for Eurocode.
A RAPT Design Code nominates which design Standard the design is to be based on as well as a set of default settings
and design parameters for that Design Code. When a Design Code is selected from the list, the settings in the data
which are code dependent will automatically be changed to those for the selected design Code. The changed values
will be highlight in blue and the tree folder colours will change to blue to indicate which data views have modified
data.
The data from the current Design Code is saved with the run data. It is listed in the list of options as Design Code
Name "SAVED" as shown above. Thus it is possible to reselect the same design code again and overwrite the Design
Code settings in the data.

Some design Standards are based on Cube Strength for concrete (BS8110, CP65, SABS0100, CP2004, IS456/IS1343)
and others on Cylinder strength (AS3600, ACI318, Eurocode 2). The Materials properties for those countries using the
different Standards are set up based on the concrete strength type used. If a designer selects a Cube Strength based
Design Standard with a Cylinder Strength based set of materials or vice versa RAPT will internally modify the concrete
strengths by a factor of .8 (/.8 if the Design Standard is Cube Strength and *.8 if the Design Standard is Cylinder
Strength) to adjust them to the Design Standard settings. This will show up in the output as a comment at the bottom
of the output for the general screen if a conversion factor has been used. The Materials data will be shown as defined
in the materials file and will not include this conversion factor. The concrete properties in the Materials Data screen will
reflect the changes caused by this modification to the Concrete Strength Type.
Material
RAPT defines the materials for each country in separate 6.2.1 Materials files. The designer can select the materials file
to use from a drop down list of the files available as shown below.

When a Materials file is selected as the file to be used, RAPT will check all of the materials currently used in the data
and select the closest option available from the new materials file in each case. These checks will be done for concrete,
prestressing materials and un-tensioned reinforcement.
The data from the current Materials Data is saved with the run data. It is listed in the list of options as Materials Name
"SAVED" as shown above. Thus it is possible to reselect the same design code again and overwrite the Design Code
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settings in the data. This materials data is accessible during the run and can be modified locally for use by this run
data only. If a change is to be made to the Default Materials file, then that file must be loaded as the current file and
saved. The modified materials File can then be reloaded into the Frame Data file by selecting it from the list.
The concrete properties, which are included in a countries Materials File, are by default defined for that countries
Design Standard. If a different Design Standard is selected, RAPT will automatically recalculate the concrete properties
to suit that new Design Standard. The designer can force RAPT to recalculate the default concrete properties for the
current code in the Materials screen.
Reinforcement Type
The designer can select from a drop down list (shown below) to have RAPT design the member as

1. Reinforced Concrete
2. Bonded Prestressed:- Partial prestress design using bonded tendons. Pre-tensioned strands can also be
defined in this type.
3. Un-bonded Post-tensioned:- Partial prestress design

Reinforced
Bonded
Prestressed
Unbonded
Post-
Tensioned
When Reinforced Concrete is selected in a prestressed file, the following warning dialog will be presented to warn that
all prestressed data will be lost if you continue (Yes). Selecting No will reverse the edit and leave the reinforcement
Type as it was previously.

Member Type
The member type may be defined as

1. Slab
2. Beam

Selection of Beam does three things.

1. It makes a Data View available in the Input Tree for Beams

2. Self weight calculations and all Panel loadings are calculated based on the overall panel width, not on the
effective width as is used for one way slabs. Thus the full panel load is applied to the beam.
3. The beam shear design will use the beam limits in most Design Standards for minimum shear reinforcement
to decide when minimum shear reinforcement requirements can be used.

Beams do not need to be placed in every span but every span must have an effective width. In this case, leave all
other dimensions as zero.
Panel Type
The panel type may be defined as

1. Internal:- Slab will extend on both sides of the column to other support lines on both sides.
2. External:- Slab will extend only to another support line on one side of the frame with the other side being a
free edge.

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This defines the location of the design panel in relation to the total floor plan. Using this choice, RAPT is able to default
sensible information into other input screens. Values such as L2, column stiffness and punching shear are all affected
by this choice. eg When an EXTERNAL PANEL is specified RAPT
1. Assumes that the columns have a torsional member on one side only, therefore affecting the Column Stiffness calculation.

2. Seeks information on external edge distances. These values are used in calculating the L2 default and in Punching shear calculations.

3. Calculates sensible default values of L2 for the defined system.

4. The outer edge of the slab, drop panels and beams are assumed to be at the free edge of the frame.

Strip Type
Defines how the bending moments and shears are to be distributed over the width of the frame being defined. The
options are:-

1. One way - Nominal Width:-

1. Slab systems:- Designs only a nominal width of the defined slab e.g. a 1000mm strip of a 8000mm panel of slab as a one
way spaning slab. There is no transverse distribution of moments. Used typically for slabs spanning between beams and
slabs spanning across walls. Self weight and panel loads are calculated for the nominal strip width in each span. Point loads
are applied to the effective (design strip) width. RAPT adjusts the frame properties to be consistent with the design strip
width. Column moments and reactions are calculated from the design strip results by factoring them by the ratio of the
transverse column spacing to the effective width. No horizontal steps or tapers are allowed in the side of the slab.
2. Beam Systems:- Will design the effective beam to support the full panel load. There is no transverse distribution of
moments. Self weight and panel loads are calculated for the panel width. Point loads are applied to the effective beam.
2. One Way - Full Width:-
1. Slab systems:- Designs the full panel width of the defined slab. The design width is the panel width at all locations. There
is no transverse distribution of moments. Used typically for slabs spanning between beams and slabs spanning across walls.
Self weight and panel loads are calculated for the full slab width. Point loads are applied to the full slab width. There is no
limitation on the use of steps and tapers to any surface.
2. Beam Systems:- Not applicable.
3. Two way:- The slab column strips and middle strips. The moments and shears are distributed to these strips
using standard distribution factors defined in most Design Standards which are further controllable by the
designer in 7.2.4.3 Loads->Lateral Distribution Factors. The designer can control the distribution of the
effects at the supports and the maximum span moment points in each span. RAPT uses a parabolic
distribution of the factors between these points to more closely match the distribution in a finite element
analysis. Flexural Design, Reinforcement Layouts and Deflection calculations are provided for each design
strip. Beam Shear calculations are only provided for the column strip.
1. Slab systems:- Can be used for any reinforcement type.
2. Beam Systems:- Only allowed for Reinforced Concrete systems. The effective beam is apportioned a fraction of the column
strip moments and shears in each span. The effective beam is designed to carry these moments and the middle strip is
designed to carry its share of the moments. Normally it is sufficient to extend the middle strip reinforcement to the face of
the beam to allow the remainder of the slab in the column strip to carry the left over column strip moment. The designer
should check to see if this will be adequate especially in situations where the portion of moment assigned to the effective
beam is relatively small.
4. Two way - Average:- This is the ACI318 method of designing two way prestressed slabs. Even though
moments and shears are distributed unevenly over the width of a slab panel, the "average" effect of this is
used in the design. The method is not allowed by AS3600 and a modified version is allowed under British
Code design rules where stricter limits are placed on the allowable tension stresses in the concrete in
recognition of the effects of averaging of the moments compared to the real moment concentrations
especially at supports. This method should not be used for partially prestressed slabs.
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Percentage of load carried by Column Strip
For Two Way Prestressed Systems, RAPT asks for a percentage of load to be carried by the column strip. The default is
70%. This figure is used when doing load balancing calculations to determine numbers of tendons for each strip and is
used as the default for the distribution factors in 7.2.4.3 Loads->Lateral Distribution Factors for the distribution of
moments and shears between design strips. The designer may over-ride these values if desired.
Column Stiffness
RAPT users can choose to model their frame run based on

1. The Equivalent Column Approach. [See T.2.1 Section Theory T2.1] Also takes into account the infinite
stiffness of the slab / beam at the column interface. This is the default and should be used for most slabs and
beams in building floor systems.
2. Net Column Stiffness. The basic column stiffness. No attempt is made to allow for torsional rotations of slabs
at the column or the effects at the slab/beam at the column interface.
3. Enhanced Column Stiffness. The stiffness of the columns taking into account the infinite stiffness of the slab /
beam at the column interface. This option should only be used for concrete portal frames, where there is no
transverse torsional member.

Note: The user can specify a Knife Edged support by defining column dimensions and a Column Stiffness or 0% or by
having defining no column dimensions in the 7.2.3.2 Column Input Screen. RAPT calculates different critical sections
for moment and shear depending on the method of input chosen. [See Section 7.5 for details]. In both cases, the
vertical shortening of the column will restrained.

Concrete Type
The designer can define multiple Concrete Types in the 6.3 Materials Data->Concrete Properties to allow for variations
in concrete properties in different areas of a country e.g. Brisbane/Sydney, Melbourne and General for Australian
concretes and also to allow for special concrete mixes such as the Boral Envisia concretes now available in some areas
in Australia. The selection from this list controls the list of concrete strengths available in the next two data items.
There will always be at least one Standard Concrete Type available in each country materials set. The designer can
add extra Concrete Types in the Materials data.

Concrete - Spanning Members

Concrete strength of the slabs and attached spanning members. This is selected from the list of available strengths in
the Materials data for the Concrete Type selected.

Some design Standards are based on Cube Strength for concrete (BS8110, CP65, SABS0100) and others on Cylinder
strength (AS3600, ACI318, Eurocode 2). The Materials properties for those countries using the different Standards are
set up based on the concrete strength type used. If a designer selects a Cube Strength based Design Standard with a
Cylinder Strength based set of materials or vice versa RAPT will internally modify the concrete strengths by a factor
of .8 (/.8 if the Design Standard is Cube Strength and *.8 if the Design Standard is Cylinder Strength) to adjust them
to the Design Standard settings. This will show up in the output as a comment at the bottom of the output for the
general screen if a conversion factor has been used. The Materials data will be shown as defined in the materials file
and will not include this conversion factor.

Concrete - Columns
Concrete strength of the columns. This is selected from the list of available strengths in the Materials data (see sample
above).
Top Reinforcement Cover
This is the dimension to the top face of the top design reinforcement layer from the outside top face of the concrete.
Should the user wish to use different covers at different points along the span it is possible to adjust this figure at each
point in the 7.2.6.3 Reinforcement->Design Zones data screen. This figure is used as the default in creating the top
reinforcement design zones. If this figure is modified after multiple design zones have been created, RAPT will modify
the cover in the design zones whose cover was the same as the old default value with the new value. RAPT will also
modify the cover to user defined bars whose original cover was the same as the original default value.
When designing cross-sections along the member, RAPT will calculate the depth to the top reinforcement to be
designed based on the top cover value at that cross-section measured to the face of the bar size nominated as the
Preferred Bar Size in the relevant 7.2.6.3 Reinforcement->Design Zones data screen.

Bottom Reinforcement Cover

This is the dimension to the bottom face of the bottom design reinforcement layer from the outside bottom face of the
concrete. Should the user wish to use different covers at different points along the span it is possible to adjust this
figure at each point in the 7.2.6.3 Reinforcement->Design Zones data screen. This figure is used as the default in
creating the bottom reinforcement design zones. If this figure is modified after multiple design zones have been
created, RAPT will modify the cover in the design zones whose cover was the same as the old default value with the
new value. RAPT will also modify the cover to user defined bars whose original cover was the same as the original
default value.

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When designing cross-sections along the member, RAPT will calculate the depth to the bottom reinforcement to be
designed based on the bottom cover value at that cross-section measured to the face of the bar size nominated as the
Preferred Bar Size in the relevant 7.2.6.3 Reinforcement->Design Zones data screen.
Top Reinforcement Axis Depth Limit
This is the minimum depth from the top surface of the concrete to the centreline of any reinforcing or prestressing
steel. In some situations, reinforcement depth is controlled by the depth to the centre of the steel, rather than the
cover to the surface (eg fire on the underside of a concrete floor to some codes). RAPT will use this limit in the
following ways

1. Top Reinforcement Zones - The covers shown in the input data for each zone will be calculated only from the
Top Reinforcement Cover requirement above. When designing reinforcement for the top zone, RAPT will use a
combination of the cover defined in reinforcement zones top at that location and this Top Reinforcement Axis
Depth Limit in conjunction with the relevant bar size to determine the actual depth to the centre of the bar
layer at that location. This will only be done at the time of calculation of section capacities and reinforcement
detailing.
2. User Defined Top Reinforcement - RAPT will check that all bar layers conform with the axis distance limit and
will give an Input warning if a bar violates this limit at any point along it's length. This will not stop program
execution.
3. Prestressing Tendons - RAPT will check that all prestressing tendons conform with the axis distance limit (for
prestressing tendons the limit is increased by 15mm in carrying out this check) and will give an Input warning
if a tendon violates this limit at any point along it's length. This will not stop program execution.

In fire situations, in general the top reinforcement is not affected by fire and this limit can be ignored. If the default
value is causing warnings when it should not be considered, then the designer should reduce this default value to a
value that no longer causes warnings to occur.

In some situations, top reinforcement can be affected by fire e.g. an edge beam with no flange overhang. In these
situations the designer should nominate a value consistent with the fire rating period required for the member being
designed.

Bottom Reinforcement Axis Depth Limit

This is the minimum depth from the bottom surface of the concrete to the centreline of any reinforcing or prestressing
steel. In some situations, reinforcement depth is controlled by the depth to the centre of the steel, rather than the
cover to the surface (eg fire on the underside of a concrete floor to some codes). RAPT will use this limit in the
following ways

1. Bottom Reinforcement Zones - The covers shown in the input data for each zone will be calculated only from
the Bottom Reinforcement Cover requirement above. When designing reinforcement for the bottom zone,
RAPT will use a combination of the cover defined in reinforcement zones bottom at that location and this
Bottom Reinforcement Axis Depth Limit in conjunction with the relevant bar size to determine the actual
depth to the centre of the bar layer at that location. This will only be done at the time of calculation of section
capacities and reinforcement detailing.
2. User Defined Bottom and General Reinforcement - RAPT will check that all bar layers conform with the axis
distance limit and will give an Input warning if a bar violates this limit at any point along it's length. This will
not stop program execution.
3. Prestressing Tendons - RAPT will check that all prestressing tendons conform with the axis distance limit (for
prestressing tendons the limit is increased by 15mm in carrying out this check) and will give an Input warning
if a tendon violates this limit at any point along it's length. This will not stop program execution.

The designer should nominate a value consistent with the fire rating period required for the member being designed.
Concrete Unit Weight
This defines the unit weight of the floor slab or concrete member to be used in the calculation of the self weight load
case. This weight should allow for the concrete plus any reinforcement in it. The Unit Weight of concrete by itself can
vary significantly but normal weight concrete is normally taken to be in the order of 24KN/m3. The reinforcement
weight will vary according to member type and the type of design. The reinforcement weight is
approximately .6KN/m3 for every 1% by volume of steel reinforcement. For a slab with 120kg/m3 of reinforcement,
this would equate to about .5KN/m3. For a beam with 350kg/m3 of reinforcement is would equate to approximately
2KN/m3. For floor slabs including beams an overall average would need to be calculated. Prestressed beams and slabs
would have a much lower component of their unit weight from steel as the amount of steel used would be in the order
of 1/3 of that used in reinforced concrete members. In earlier versions of RAPT where it was not possible to define
this weight, concrete density was used in the calculation of self weight.
RAPT will calculate a default value equivalent to the concrete density plus 1KN/m3. If the concrete density is modified
in the materials data, this data item will be adjusted to suit the new concrete density.
Self Weight Definition
By default RAPT will calculate the self weight of the concrete frame that has been defined and place it in the self
weight load case. These values are not editable but extra loads or either sign can be added by the designer. Here,
RAPT gives the designer the option to ask RAPT not to calculate the self weight of the frame. It is then the designers
responsibility to enter in the loads or a bending moment/shear diagram for the self-weight case and to modify this
whenever changes are made to the input that would require loads to be recalculated. RAPT will adjust load positions
and end locations when spans are added or span lengths change but cannot be expected to make other modifications
to loads that may result from shape changes or if bending moment diagrams have been defined.
The options are

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1. Program Calculated:- All loads in the self weight case will be deleted. RAPT will recalculate the frame self
weight loads and place them in the self weight load case. The following warning will be given.

2. User defined:- When this is selected, RAPT will delete all program calculated self weight loads. Other user
defined self weight loads will be retained. The designer can then add extra loads to define the self weight of
the frame. The following warning will be given.

Pattern Live Load

RAPT will automatically create the load cases required to satisfy the requirements of different design codes for the
default patterning of Live Load on alternate and adjacent spans. The designer can select, in 7.2.7.5 Design data-
>Pattern Load, to use pattern live load cases in different areas of design. The default is to use patterning of live load in
all areas if it is selected in the General Screen.
Design Standards define the percentage of load that should be applied for patterning of the live load. Also, the method
used in patterning live loads varies from Standard to Standard. For more information on patterning of loads for various
Design Standards see the relevant standard. RAPT follows the method defined in each standard in terms of load
pattern and factors exactly as defined in that design code.
Only the load case named Live Load will be patterned. The combination factors used for this case are used for the
envelope of actions created for the patterned live load. RAPT will create two live load pattern envelopes, one based on
the envelope of moments at each design location with co-existing shears and one based on the shear envelope at each
point with co-existing moments. For BS8110 based design codes, RAPT will also use different Dead Load Combination
Factors for loaded and unloaded spans.

RAPT will automatically reduce continuous live loads to span based loads to achieve load patterning. It is not necessary
for the designer to do this manually.

Designers should be aware that this patterning of live load only covers the default live load patterns defined in design
standards, consisting of different combinations of loaded and unloaded spans. All design standards also require that
designers account for any load pattern that can be expected to occur for the specific building that they are designing.
The designer can create load cases and load combinations to account for any load pattern they wish to define, either
as Alternate Live Loads which will be included automatically in any load combination that includes Live Loads or as
Other Load Type for which the designer will have to create load combinations for any area of design that is to include
that load pattern.
Earthquake Design
The designer can request that earthquake design rules be applied in designing and detailing for flexure and shear. The
options are

1. None
2. Moderate Risk
3. High Risk

When options 2 or 3 are selected, RAPT will copy the 5.5 Design Standard->Earthquake Design default data into the
7.2.7.4 Design Data->Earthquake Design, replacing any settings that had been made previously.
Moment Redistribution
The designer can define a % of moment to be redistributed. RAPT will then redistribute the ultimate moment envelope
and the associated shear envelope for Ultimate strength calculations. Serviceability load combinations remain
unaffected.
Where the Ultimate moment at a design point is of a different sign to the service moment, RAPT will apply a factored
Ultimate Moment of the same sign as the service moment equal to 1.2 x M service to ensure that there is sufficient
strength on any face that will be tensile through any of the loading stages of the member.

If Moment Redistribution is requested, RAPT will automatically apply all limitations to the design for ductility as defined
in the different design codes. It will over-ride any user defined setting for depth of neutral axis limit in the 7.2.7.1
Design Data in doing this unless the defined value is less than that calculated from the Design Standard rules.
Designers should be aware that the use of large amounts of redistribution of the moments in a member introduces
severe limitations to the ductility requirements of a member due to the reliance in the strength calculations on
increased rotations at plastic hinges. It also could introduce a requirement for extra reinforcement under service load

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conditions to control crack widths. The resulting design could be less economical than a design without or with lesser
redistribution of moments.

RAPT does not redistribute moments at end columns. To redistribute moment from an end column, a user should use
the option to modify the Izz of a column in the F3 Columns screen.

RAPT will only allow redistribution of moments for 7.2.3.2 Braced Frames. RAPT will limit the % redistribution defined
in the input to the maximum allowed by the relevant design standard. It will allow both positive (reducing support
moments) and negative (increasing support moments) values of the redistribution %.
The maximum limits are

1. AS3600:- 30% for Class N ductility reinforcement and 0% for Class L ductility reinforcement
2. ACI-318:- 15%
3. Eurocode 2:- 30% for class B or C reinforcement and 20% for class A reinforcement (Low Ductility).
4. BS8110, CP 65, IS456/IS1343 and SABS0100: 30% for reinforced concrete members and 20% for
prestressed members.
5. Hong Kong CP2004: If concrete strength less than 70MPa, 30% for reinforced concrete members and 20% for
prestressed members. If concrete strength is greater than 70MPa, no redistribution is allowed.

RAPT now uses two different redistribution methodologies depending on the load types defined

- Basic redistribution (old method pre version 6.3) The overall design envelope is calculated and then the whole
envelope is redistributed by the requested percentage. This is now only done for cases where Moment Envelopes are
defined. This includes Moving Load cases.

- Complex Redistribution is now done for all other load situations. In Complex Redistribution, each individual load
combination (including each individual LL pattern load combination and Alternate LL combinations) is redistributed in
the direction indicated by the designer and by a maximum of the amount requested but not by an amount that will
result in an increase in the maximum moment causing tension on the other face of the member. To explain the
procedure, For a redistribution from Support Hinges to Span,

• The un-redistributed Envelope is calculated. The maximum amount of redistribution possible is then
calculated from the peak moments at the supports in each span, except at end columns where no
redistribution is allowed.
• The individual load combinations are then recalculated and each combination is compared to the overall
envelope. The redistribution is then applied to this combination but only to the extent that it reduces the
critical Span Moment to the maximum span moment of the initial envelope of all of the combinations. So the
Maximum Span Moment is never increased.

The overall effect is to compress the overall envelope towards the maximum moment causing tension on the other
face, rather than shift the overall envelope. For +ve redistribution, the -ve moments are reduced towards the peak
+ve moments and vice versa for -ve redistribution.

For negative redistribution, the same approach is taken but the redistribution is based on the maximum span moment.
In this case, as increasing the support moments will increase the moment transfer to the columns, the redistribution is
limited so that the moment transfer to the columns is not increased. This will normally severely limit the amount of -ve
redistribution that is possible, especially in end spans.

Design Surface Levels

The designer can request that RAPT use one of the following methods to define the concrete surface level from which
RAPT will measure cover in the positioning of reinforcement and prestressing tendons in a member.
1. Reduced Surfaces - Will use the minimum depth of the the relevant surface (top or bottom) within 50mm either side of the centreline
datum of the frame. This will be the extreme surface level in most cases. In situations where void elements have been defined to
remove some of the top or bottom surface, this may result in RAPT selecting a reference level different to that required by the
designer. Some examples of the effects of this selection are shown below.

2. Extreme Surfaces - Always selects the extreme concrete surface over the full width of the design strip on
the relevant face.

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RAPT will set the Design Surface Level as Extreme Surfaces until Concrete Elements are added to the input. When
these are added RAPT will automatically change the setting to Reduced Surfaces to allow for the possibility that a void
element will cause a logical reduction in the design surface level. No matter which option is selected for complicated
frames, it may be necessary for the designer to modify the defined tendon covers or reinforcement design zone depths
to ensure that they are positioned at the required depth in the section for a particular design example.

Eurocode Ultimate Load Combination Basis

Eurocode EN1990:2002-2005 in Table A2.4(B) defines two options for the Design Values of Actions for Strength. These
are defined as

• Eqn 6.10 - Full factor is used on Dead Loads and Full factor used on the First Live Load and Combination
Factor on all other Live Loads
• Eqns 6.10a - Full factor is used on Dead Loads with Combination factor used on all Live Loads
and 6.10b - Reduced factor used on Dead Loads with Full factor used on the First Live Load and Combination
Factor on all other Live Loads

The standard makes no recommendations as to which set should be used and suggests that there will be guidance in
the National Annex for each country.
This option is only available for Design Standards based on Eurocode 1992-1-1.

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7.2.3 Frame Shape Screen Layout

The general layout of the windows in the concrete frame input is as shown above. The data grid may be a single grid
as shown above or Control/Child grid combination as is used for the 7.2.3.7 Steps input. Refer to 4.5.1 General Screen
Layout Principles for discussion on the general layout features of windows in RAPT. Two separate sets of graphics
windows are provided to give the user various views of the concrete shape. These are described below.

Frame Graphics Window

This window shows the graphic view of the full concrete frame. Three separate views of the frame are available
controlled by the View Selector Buttons. These are

Elevation View:- Shows an expanded elevation view of the concrete member with only the connecting part of the
columns. The frame is scaled to fit the view so the vertical to horizontal scale is distorted. The scales are shown in
both directions. The elevation is shown viewed from the bottom of the plan view.

Full Elevation View:- Shows the full elevation of the concrete frame including the full height of the columns and
the column end conditions. The frame is scaled to fit the view so the vertical to horizontal scale is distorted. The
elevation is shown viewed from the bottom of the plan view.

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Plan View:- Shows the top plan view of the concrete panel. Columns and column capitals are not shown. The
frame is scaled to fit the view so the vertical to horizontal scale is distorted.

FRAME GRAPHICS WINDOW TOOLBARS

When a location is selected in the graphics by clicking at a point or moving the cursor using the toolbar buttons, the
location of the cursor from the left end of the frame will be shown in this toolbar data cell.
Alternatively, the user can move the cursor to a new position by entering the location here and pressing enter. The
location can be defined as a value from the left end of the frame e.g. 10000 or as a location from a column e.g.
2;10000.

Zoom (Ctrl + Z). This button will toggle between full screen mode and span zoom mode for the graphics in a
window. In span zoom mode, the current span will be shown with the half span either side (if a cantilever is the
previous or next span, the full cantilever will show) scaled to fill the whole window. The scales will still show at the left
and right sides of the window. The horizontal scale will change to suit the new length of the graph being shown in the
Window.

Move to next item (Ctrl + Right Arrow). If in Full Screen Mode, changes to Span Zoom Mode and moves
the next span to the centre if the window. In Span Zoom mode, the next span will move to the centre of the Window.

Move to next point (Shift + Right Arrow). Move to the next change in section location in the frame. In
Span Zoom mode, the span containing the next change in section point will move to the centre of the Window and the
cursor will move to that point.

Move to previous point (Shift + Left Arrow). Move to the previous change in section location in the frame.
In Span Zoom mode, the span containing the previous change in section point will move to the centre of the Window
and the cursor will move to that point.

Move to previous item (span) (Ctrl + Left Arrow). If in Full Screen Mode, changes to Span Zoom Mode
and moves the span to the left of the current span to the centre if the window. In Span Zoom mode, the span to the
left of the current span will move to the centre of the Window.

Zoom to user defined rectangle. This button is only available in Full Screen Mode. Click the button and then
use the mouse to select a rectangle within the graphics into which you want to zoom. To do this, click and hold the left
mouse button at the top left or bottom right corner of a rectangle and move the mouse to create a rectangle that
encloses the area you wish to zoom into. The relative scale of the zoomed area will be the same as that for the Full
Screen Mode so, if you make the selected rectangle shape exactly the same relative proportions as the Window, the
rectangular shape you have selected will fill the entire window. Otherwise, the relative scale will still be maintained so
a larger shape will be shown to ensure that the full selected rectangle is in the view: depending on the relative shapes
of the rectangle and the Window, more width or depth of the graph will be included than requested.

7.2.3 Frame Definition and Design: Frame Shape Screen Layout 2