Procedure 4 Large Structures Construction Stage Analysis)
5.4.4 Choice of Tendon Constraint Point Types
The following Constraint Point Types are available to specify the tendon geometry.
Normal: Using the type “Normal” we specify fixed points in space where an internal or external tendon has to go through. The tangent at this point can be free or constraint (value). Eleva- tion and plan are separately calculated, i.e. the direction may be prescribed in the elevation and free in the ground plane ore vice versa. This point type is set by the program as de- fault, and generally used in the definition of internal tendons for all points except the start points of straight sections (For the correct use of this function for external tendons see chap- ter 5.5 External Pre-stressing).
Line: This type serves for defining a start point of a straight tendon section. This might be the begin of a straight part of an inter- nal tendon or the begin of a straight part of an external ten- don. The direction of the tangent is automatically defined by the position of the point and the position of the next point. If the type “Line” is used in the external tendon definition for defining the start of a straight section after a tangent intersec- tion point, then the entered position in the cross-section is not used, but the intersection point of the straight connection line between the tangent intersection points and the cross-section plane.
The following types are (besides the type “Line”) only provided for (mostly external) tendons, where alternating straight sections and more or less circular deviation sections are arranged:
Line (free Y): As with “Line”, the begin of a straight tendon part is speci- fied with this type. But with this type, this is done for start points after a straight section and a subsequent curved seg- ment. Together with the next segment the 3 segments must be in a common plane. Therefore RM2000 calculates the plane built by the 2 previous points and the subsequent point, and changes the Y coordinate of the actual point such that the point lies in the prescribed plane (see also chapter 5.5.2 and 5.5.3).
Intersection point: With this function an intersection point of two tangents or a fixed constraint point can be defined (e.g. tangent intersec- tion point of a deflection sheave or end point of an external tendon).
Free node at element: With “Free node at the element” a point of the tendon with variable position can be defined. The exact position will be calculated with the specified constraints (e.g. transition of a straight external part to the internal part in the region of the deviator or intersection point of the straight part to the curved deviator block, see also chap. 5.5.2).
Intersection point (free): An intersection point (free) can be used if the position of this point should be calculated by the program in the way that it becomes a point of the plane defined by three constraint points (see chapter 5.5.3 Geometry Definition by Specifica- tion of Straight Segments (Type 2).
5.4.4.1 Graphic input facilities
Selecting the button above of the constraint point table a graphic presentation of the assigned element series together with the tendon geometry and the cross-sections opens. The user can select if he wants to see the tendon geometry in the cross section or a view of the definiton (Vertical, side, ground view).
If a super-elevated view is wanted this has to be defined in ‚plstruct.rm’. It is possible to change in the first line the parameters Scf-x, Scf-y and Scf-z (file editor or in
"RESULTS #PLSYS).
The super-elevation is equivalent to the one defined in PLSYS.
The new window is split into three parts:
a) The interactive graphic screen (right, central)
b) The input part (left, only active for ‘new’ input or for editing)
c) The table at the bottom of the window displays the geometry points already input.
a) Graphic presentation window:
The radio buttons at the top of the window can be used to display either a
# Cross section or a
# Perspective view The value
% TxtFact
is used to influence the size of the presented element labels.
A vertical line presents the current position of the tendon definition in both views.
There are four buttons at the top of the graphic screen:
These buttons use the dz step for the cursor if Cross Section View is selected and use the dx step for the cursor if the Perspective View is selected.
Cross-section view:
• << move the cursor to the extreme left side of the cross section or
• < move to the left using the dz step for the cursor or
• > move to the right using the dz step for the cursor or
• >> move the cursor to the extreme right side of the cross section or Isometric view:
• << move the cursor to the end of the first assigned element.
• < move in the longitudinal direction (+X) using the dx step for the cursor
• > move in the longitudinal direction (-X) using the dx step for the cursor
• >> move the cursor to the end of the last assigned element.
Four further buttons are on the right hand side of the screen. They are equally used for the cross-section view and the isometric view:
• ++ move the cursor to the top of the cross section
• + move upwards using the dy step for the cursor (which is user defined)
• - move downwards using the dy step for the cursor (which is user defined)
• -- move the cursor to the bottom of the cross section
b) Constraint point table
The constraint point table is displayed on the bottom edge of the window in order to keep the information about the actually active constraint point resident. The effect of changes is there immediately visible.
Changing the position in the graphics does not change the active constraint point. Only the parameters shown in the input part of the window are adapted. These parameters are transferred to the active constraint point if the function „Apply“ is selected in the
„Modification“ case.
The active constraint point in the constraint point table also determines the position, where a new constraint point is inserted when the function „Apply“ is selected in the
„Insert“ function.
c) Input part
The user can define the eccentricity directly or use to use the graphical facility of stepping in either direction inside the cross sections as de- scribed above.
Step dx Increment for moving the cursor cross lines around the inside of Step dy the cross section or along the element axis. It is mainly used to
Step dz specify a tendon constraint point relative to the top, bottom, left or right of the cross section (not referring to the centre of gravity)
Apply Select this button to store the current definitions for the new or modi- fied tendon constraint point. The new tendon constraint point defini- tions will be immediately displayed in the input table at the bottom of the screen.
The Main Input table (not the table below the graphical screen displayed with ‘Info’):
All tendon constraint points for the tendon geometry are defined/modified/deleted in this table. (N.B. the point can only be deleted in the main data table – not via the ‘Info’
button!) To insert a new tendon constraint point select the appropriate line and use the
‘insert after’ or ‘insert before’ buttons to activate the input. Choosing the ‘Edit’ button for the selected line also activates the input.
The tendon profile defined via this ‘main Input table’ can be checked graphically after- wards by selecting the ‘Info’ button.
The 3-dimensional coordinates of the profile constraint points can also be checked by choosing ‘3D-Values’.