Helix

After selecting reinforcement in the form of helix, the Special reinforcement dialog displays:

Note: The helix is defined for two types of cross-section of an RC structure element (contour):circle or regular polygon.

To define a bar, the following should be specified:

• Bar diameter (the diameter defined in the dialog is adopted by default)
• Reinforcing bar cover (the cover defined in the dialog is adopted by default)
• In the Shape parameters field - anchorage parameters for reinforcing bar ends, i.e. hook angle and length; you can lock a hook length by selecting the option next to the edit field for defining a hook length ( appears). The edit field becomes inaccessible. If you modify parameters (length or diameter) of a bar with locked hook length, the hook length does not change.

The helix is a three-dimensional reinforcement. This reinforcement type is defined in the drawing plane. The helix is defined in two stages:

• Definition of reinforcement within the cross-section of an RC structure element (e.g. column)
• Definition of reinforcement along the length of RC structure element.

Note: It is possible to modify a helix pitch during definition of this reinforcement type.

Total length of this reinforcement type is calculated according to the following formula:

L = C / B * p * (A + d) + hook lengths

where (see the drawing below):

L - total helix length

C - helix length in plane

B - helix pitch

A - helix internal diameter

d - bar diameter.

While defining the helix, the following icons are available in the right part of the dialog:

• Points - used to define a closed region by specifying circle center and circle radius (or diameter) as well as indicating a region of reinforcement distribution - beginning and end of the region within which reinforcement is distributed (e.g. along the column length)

  Command line:

  Definition of reinforcement within a cross-section

  Circle center [2Points / 3Points]

  Circle radius [Diameter]

  Definition of reinforcement along the length of reinforced element

  Select first point

  Select second point [Spiral pitch]

  where:

  a circle is defined within the cross-section by specifying: circle center and circle radius/diameter or by determining 2 or 3 points belonging to a circle

  first point - beginning point of the helix along the length of an RC element

  second point - end point of the helix along the length of an RC element

  spiral pitch - value of the helix pitch

• Pick point - is used to search a closed region by clicking inside the region. After selecting, the dialog closes, and the cursor assumes the form of a cross (see the ACAD command 'copy' - the stage of indicating the beginning and end points). Once any point is selected, the minimal contour is detected; the helix is defined by indicating the following geometric figures: regular polygon and circle; to conclude the operation, you have to indicate the region of reinforcement distribution - beginning and end of the region within which reinforcement is distributed (e.g. along the column length)

  Command line:

  Definition of reinforcement within a cross-section

  Select internal point of the object

  Orientation

  Definition of reinforcement along the length of reinforced element

  Select first point

  Select second point [Spiral pitch]

  where:

  a circle is defined within the cross-section by specifying an internal point of a circle or regular polygon and indicating positions of hooks (orientation)

  first point - beginning point of the helix along the length of an RC element

  second point - end point of the helix along the length of an RC element

  spiral pitch - value of the helix pitch

• Select - is used to indicate a contour directly. After selecting, the dialog closes, and the cursor assumes the shape of a square (see the ACAD command 'copy' - the stage of selecting an object for copying). Once any point is selected, the ACAD object is detected on the screen and reinforcement is drawn within an indicated object.

  Command line:

  Definition of reinforcement within a cross-section

  Select object

  Orientation

  Definition of reinforcement along the length of reinforced element

  Select first point

  Select second point [Spiral pitch]

  where:

  a circle is defined within the cross-section by selecting a contour (of a circle or regular polygon) and indicating positions of hooks (orientation)

  first point - beginning point of the helix along the length of an RC element

  second point - end point of the helix along the length of an RC element

  spiral pitch - value of the helix pitch

See also:

Example of helix definition