After Auto optimization Design
6.2 Design Parameters
6.3.2 Plan Beam Settings
Plan Beam
This is the section where you can set the beam design and detailing parameters. Click on Plan Design and Detailing Parameters command > Plan Beam folder to bring up the form. In this form, you can select the following options:
Automatic main bar selection and spacing
· Minimum diameter (mm): Select the minimum reinforcement bar diameter allowable from the pull down list.
This list is derived from Project Design Parameters command > Steel Reinforcement Diameters.
· Maximum diameter (mm): Select the maximum reinforcement bar diameter allowable from the pull down list.
This list is derived from Project Design Parameters command > Steel Reinforcement Diameters.
· Reinforcement bar (N/mm2): Specify the steel characteristic strength for the reinforcement bar in the beam section. The pull down list is derived from Project Design Parameters command > Characteristic Strength.
· Minimum centre to centre spacing (mm): This option allows you to specify the minimum distance between two centre to centre reinforcement bars.
· Maximum centre to centre spacing (mm): This option allows you to specify the maximum distance between two centre to centre reinforcement bars.
Automatic stirrup selection and spacing
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· Minimum diameter (mm): Select the minimum stirrup bar diameter allowable from the pull down list. The list is derived from Project Design Parameters command > Steel Reinforcement Diameters.
· Maximum diameter (mm): Select the maximum stirrup bar diameter allowable from the pull down list. The list is derived from Project Design Parameters command > Steel Reinforcement Diameters.
· Reinforcement bar (N/mm2): Specify the steel characteristic strength for the stirrup bar in the beam section.
The pull down list is derived from Project Design Parameters command > Characteristic Strength.
· Minimum link spacing (mm): This option allows you to select the minimum distance of two centre to centre spacing links.
· Maximum link spacing (mm): This option allows you to select the minimum distance of two centre to centre spacing links.
Other parameters
· Concrete characteristic strength (N/mm2): Allows you to specify the concrete grade of the pad footings.
· Steel percentage of reinforcement bar (%): Set this figure for the minimum reinforcement provided for beam. This figure varies are according to the code of practice adopted.
By default the steel percentage of reinforcement bar is set to 1%.
· Top or bottom concrete cover to longitudinal bar (mm):
Specifies this figure to provide the design depth of concrete
cover to longitudinal bar. By default this value is set to 25mm.
· Side concrete cover to longitudinal bar (mm): You can specify the concrete cover from the side of the beam to the centre of longitudinal bar.
· Vertical clear spacing between two layers of longitudinal bar (mm): Clear face to face spacing between two layers of longitudinal bar in millimetre.
· Two rebar sizes auto-combination for multi-layer longitudinal rebar: Checking this option convert two rebar sizes into one equivalent rebar size.
Figure 6.17: Plan Beam Parameters
6-96 Beam Detailing Parameters
You can configure the beam details to your preferences in this form.
The changes made in this form apply only to the selected active floor.
You must save every time you made changes for the configuration in order to be effective. Refer to the figures 6.18 for the description of the detailing parameters. Below are the options available in the Beam Detailing Parameters form:
· Minimum length of rebar bent at end of beams (mm):
Length of reinforcement bar starting from end of the bent until the end of the bar. (Refer to figure 6.22)
· Clear gap between sections of detailing (mm): The distance between each cut section of beams. (Refer to figure 6.21)
· Position of span's dimension line: Select from the pull down list to set the location of each span's dimension either at top or bottom of the beam.
· Bottom bar lapping at support: Selecting this option from the pull down list determines the bottom bar lapping type at support. (Refer to figure 6.19) You can select the following types:
· Crank bar - The bar lapping length is based on the larger diameter of the reinforcement bars,f multiply by the tension bar anchorage coefficient as specified in Project Parameters > Project Detailing Parameters.
· Straight bar - For doubly reinforced beam section which requires compression reinforcement, the straight bar is provided to satisfy the area of reinforcement required. For
nominal reinforcement, the program assigns minimum reinforcement bar size specified in the Project Parameters > Project Design Parameters. You can view the calculations of the reinforcement bar assignments in the beam report.
· Automatic bar - Selecting this option allows the program to assign the type of bottom bar lapping at support based on the below conditions:
i) Crank bar on automatic selection adopts the lapping length based on the smaller diameter of the two bars. To satisfy this requirement, the ratio of larger/smaller reinforcement area must not exceed 2.
ii) If above requirement fails, the program assigns the crank bar lap length based on the larger diameter of the reinforcement bars.
iii) Straight bar lapping is provided if reinforcement at bottom support exceeds the middle span bottom reinforcement.
· Underline beam mark for every span mode: Selecting this option underlines mark of the beam. (Refer to figure 6.20)
· Beam section cut is looking from left end of the beam:
Checking this option views the beam cut section from the left of the beam.
· Distance of section mark from beam elevation details (mm):
· Ratio of top support bar curtailment as percentage of span length: This option allows you to determine the curtailment length of the top support bar as defined in BS8110: Part 1: Clause 3.12.10. (Refer to figure 6.19).
· Maximum length of bottom rebar before continuation at support (mm): Set this value for the allowable length of single continuous bottom rebar spanning one support to another support.
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· Minimum length of top rebar before continuation at mid-span (mm): This option overwrites top support bar curtailment length if the ratio is less than this specified length.
· Incremental dimensional figures in rebar curtailment (mm): Length of bar curtailment increases by this specified figure.
· Maximum size of bar diameter for cranking bar:
Selecting the bar diameter size from the pull down list. In the detailing, any bar diameter size more than the allowable size will be automatically change to straight bar lapping. This option is only applicable when the lapping type is set to cranking bar.
· Order of beam sizes in beam mark detailing: Selecting this option to determine the style of beam mark in the detail drawing. You have the options of choosing (width x depth) or (depth x width). For example, you have a beam of 230mm in width and 600mm in depth. Selecting (width x depth) type displays the beam mark as (230 x 600) in the drawing. (Refer to figure 6.20)
· Arrow line for the link: This option allows you to choose the type of stirrup links naming style.
· Detail of stirrup: Checking this option displays the number of stirrup links required in the beam detailing.
· Detailing of distance with/without or no gap: You can select whether you want to display the distance of stirrup links in the beam details.
· Symbol of detailing: Select the style of stirrup links in the beam detailing.
Note : To apply the settings to all floors, set the parameters in File menu > Setting Parameter Template command before creating a new project instead.
Figure 6.18: Typical beam details
Figure 6.19: Section A shows crank bar and ratio of top support bar curtailment
Figure 6.20: Section B shows options of underlining beam mark and beam mark order
6-100 Figure 6.21: Section C shows clear gap between sections of detailing
Figure 6.22: Section D shows the length of rebar at end of beams
Figure 6.23: Beam Detailing Parameters
Beam Subframe Design Configuration
The program allows you to select the method of analysis you want to adopt for your design. In the Beam Subframe Design Configuration area, you have the option of:
· Subframe design for beam: Checking this option allows the program to analysis the model using subframe analysis method.
· Pin support condition at first and last supports: This option allows you to set the beam support conditions to pin fixity at first and last support. For monolithic structure in frame design, the first and last supports carry moment.
However overwriting this condition to pin support allows the moment to redistribute the moments to the internal span.
Continuous Beam Design Control Factors
You can analyze the structure using continuous beam method.
However the continuous beam method requires satisfying the factors below. If any of the factors being exceeded, the program will run analysis adopting subframe design analysis.
· Beam span greater than (mm): This option allows you to specify the maximum allowable beam span for the continuous beam method. The program automatically converts to subframe analysis if beam span is greater than value specified here.
· No: of floors greater than: If any number of floors greater than the value set here, the program automatically converts to subframe design analysis.
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· Relative column/beam stiffness greater than: You have the option of defining the allowable column/beam stiffness before the program convert to subframe analysis.
· Adjacent span length difference greater than (%): Any difference in span length greater than this percentage specified here automatically convert to subframe design analysis.
· Differential fixed end moments percentage greater than (%): If the fixed end moments determined using continuous beam method are greater than the percentage specified here, the program automatically convert to subframe analysis.
Figure 6.24: Beam Subframe Design Configuration Parameters
Special Design Parameters
· Stirrup bar characteristics strength (N/mm2): Specify the strength of the shear reinforcement links provided for beam design.
· Maximum beam width using the above strength of smallest stirrup (mm): Specify the allowable width to adopt the above characteristic strength for stirrup.
· Maximum drop for continuous beam analysis (mm):
Specify the maximum allowable drop for the beam to behave as continuous spans. Drop with more than the maximum allowable drop be assumed as new beam span.
· Maximum difference span's width for continuous beam analysis (mm): This option allows you to specify the maximum difference in span's width to consider as continuous beam. For example, you have set this value to 100mm. You have two adjacent span beams with width of 125mm and 250mm respectively. The difference of beam's width is 125mm and it has exceeded the allowable difference width of 100mm. Therefore the program considers these beams as simply supported.
Figure 6.25: Special Design Parameters for Beam form
6-104 Requirement of Code of Practice
· Minimum depth of beam requiring side rebars (mm):
Specify the value for the provision of longitudinal bars near side faces of the beam.
· Maximum spacing anti-crack bar side rebar (mm): This option allows you to specify the maximum distance between anti-crack bars at the near side faces of the beam.
· Degree of upper/lower end column fixity for subframe analysis.
· Stirrup check for compression bar buckling.
· Most critical live load reaction mode: Enabling this option allows the program to determine the most critical load combinations by applying pattern loading on the beam.
Disable this option allows the beam to be fully loaded with one loading condition of 1.4G + 1.6Q. This option is defined in BS 8110: Part 1: 1985 and 1997 Clause 3.2.1.2.2.
· Design moment at column face: This option allows the program to design beam based on design moment at column face instead of the support.
· Design shear at column face: Enable this option allows the program to design beam based on design shear force at column face instead of the support.
· Automatic deflection control by increasing compression bar: With this option, the program automatically increases the compression bar until the deflection control governs.
With additional reinforcement area provided, the compression modification factor increases. This enhances the
allowable span/depth ratio. Additional reinforcement areas provided are shown in the beam result. The compression reinforcement area allowable is up to 2% of the gross cross-section area of the concrete. The program displays warning if compression reinforcement area required more than 2% of the concrete area for deflection control.
· Support moment redistribution: Checking this box allows the program to apply moment redistribution to the beam analysis. This option here overwrites the same setting in Project Design Parameters.
Figure 6.26: Requirement of Code of Practice parameters
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Plan Slab Settings Plan Slab
This is the section where you can set the slab design and detailing parameters. Click on Plan Design and Detailing Parameters command > Plan Slab folder to bring up the form. In this form, you can select the following options:
Centre to centre spacing
· Minimum spacing: The minimum allowable distance between bars
· Maximum between main bar: Maximum allowable distance between bars
· Maximum between distribution bar: Maximum allowable distance between longitudinal bars
Automatic bar selection (mm)
· Minimum bar: Setting this value allows the program to determine the minimum bar size to be used in the slab section design.
· Maximum bar: Setting this value allows the program to determine the maximum bar size to be used in the slab section design.
Characteristics strength (N/mm2)
· Concrete: Specify the slab concrete characteristic strength for the section design.
· Reinforcement bar: Specify the characteristic strength of the reinforcement bar.
6-108 Design options
· BRC slab: Enabling this option adopts BRC reinforcement type for slab.
· Top BRCB: Checking this option adopts BRC rectangular mesh type for top reinforcement. Uncheck this option alone adopts BRC square mesh type reinforcement bar for the top reinforcement layer.
Others
· Steel percentage of reinforcement (%): Set this figure for the minimum reinforcement provided in the pad footing. This figure varies are according to the code of practice adopted.
By default the steel percentage of reinforcement bar is set to 1%.
· Concrete cover to longitudinal bar (mm): Clear cover of concrete from the slab face to the surface of the main steel bar in mm.
· Maximum drop for continuity over support (mm): This option allows you to specify the maximum allowable drop for the slabs between supports to be continuous. Any value greater than this will automatically consider as discontinuous slabs at that support.
· One-way slab moments increment (%): You can increase the design moments for slabs that are determined as one-way.
By default this value is set to 15%.
Figure 6.28: Plan Design and Detailing Parameters form
6-110 Slab Detailing Parameters
User has the options to configure the slab details in this form.
Changes made in this form apply to the selected active floor only.
You must save every time you made changes for the configuration in order to be effective. Refer to the figures 6.29 for the description of the detailing parameters. Below are the options available in the Slab Detailing Parameters form:
· Ratio of top bar support bar curtailment as percentage of span length (%): This option allows you determine the length of the support bar curtailment based on the percentage of the slab span length. Refer to BS8110 1985 Part 1: Figure 3.25 for further explanation.
· Clear gap between sections of detailing bar (mm): The distance between each cut section of slabs.
· Incremental dimension figures in bar curtailment (mm):
Setting this figure allows the program to increase or decrease the next suitable bar curtailment length by this value.
· Minimum anchorage length at discontinuous edge support: This option allows you to set the minimum anchorage length at the discontinuous edge support in millimetre (mm). By default, the length is set to 600mm.
· Position of span's dimension line: Specify the location of the span's dimension from the pull down list. You can select the span dimension position on the top or bottom of the slab.
· Underline slab mark for every span mode: Selecting this option will underline every marking of the slab.
Figure 6.29: Slab Detailing Parameters form
7-112 7.1 Drawing Gridlines
You can create the grid lines using the three following methods:
· Grid input generator - Defining the grid line using grid generator wizard.
· Click grid and drag method - Graphical interface input in the active window.
· Table input - Editing and modify grid line properties.
The above methods are described in the later sections of this chapter.
The table below describes the function of each icon in the Input Grid command:
Command Icon Description
Batch grids input Multiple gridline input generator
Increase indent Shift grid mark to right or down
Decrease indent Shift grid mark to left or up
Grid count Displays number of gridlines in the layout
Cumulative grid distance Displays distance of gridline from the initial position.
All dimensions are in millimetres, mm.