Input of Reinforcement Fields

In view of the slab geometry in both directions a continuous bottom reinforcement is placed. In order to start the reinforcement in the Xdirection, ensure that the Xreinforce ment is activated (button on left). Thus everything is ready for the reinforcement in the Xdirection.

. The X-direction chosen here (or Y-direction) thereby corresponds to the current coordinate axis, which is defined in the dialogue ’Input Options’ (button on left boundary). Since the X- and Y-axes may be arbitrarily oriented, the input of sloping reinforcement is also poss- ible.

Click on the button ’Input Reinforcement Field’. The following dialogue window ap pears:

vertical position

preview

choice of bar and mesh posi# tions

properties bar position

bar and laying direction (only active if fields selected)

anchoring conditions (no influence on calculation; serve only as additional informa# tion for preparing a reinforce# ment plan)

This dialogue shows all attributes of a reinforcement field. For the example slab no steel meshes should be used. One chooses therefore the setting Bar Field. Before construct ing the geometrical extent in der plane of the slab first define the vertical position by assigning to Zone 1:

for zone selection with mouse

For constructional reasons a minimum reinforcement often has to be placed. This can be done directly in the input of the reinforcement fields, by specifying a minimum content in the Register/Design/. For the example choose a geo metrical reinforcement content of 0.15%(according to SIA code), which corresponds to a minimum reinforcement area of 3.3[cm2ńm].

Each reinforcement field can have a different steel quality, which can be specified in the Register/Options/. In most

D 3 Reinforcement Module Part D Reinforcement and

cases, however, one uses the same steel as chosen already in the project settings (shown here in light grey).

On opening the dialogue the drawing tools shown on the left are activated, enabling one to construct rectangular and polygonal fields. The bottom reinforcement in the X direction can be input as a rectangular field, by pressing either the button [Introduce] of the dialogue or on the button and then on the left lower and right upper corner of the plan outline. The reinforcement field just constructed is now shown on the screen as a broken−lined rectangle (=effective static zone) with a labelled continuous rein forcement bar. The labelling is positioned on the bar, is in its direction and shows the current reinforcement area. Since dimensioning has not yet been carried out, it corre sponds at the moment to the prescribed minimum content.

. The labelling, beside the current reinforcement area, shows other attributes of a field as well, e.g., by means of an underlined text, that a minimum content was prescribed. For further ex- planations on this topic see Chapter D 3.2.8

In order to input the same Yreinforcement, without closing the dialogue, press on the register button shown on the left. Thereby the preview graphics and the values for the directions in the dialogue can be adjusted, while the other settings remain unchanged. Analogous to the Xreinforcement construct now the reinforcement field in the Ydirec tion by pressing on the button [Introduce] and then click on two opposite plan outline corners.

Duplicating in another direction

For the frequent case of having the same fields in both reinforcement directions, instead of the above de scribed input method one can use the convenient duplicating function:

In order to use this here, firstly undo the input of the second reinforcement field (CTRLZ=Undo). Then select the field in the Xdirection (click left mouse button). In the Object Menu (click right mouse button) then choose ’Duplicate in another direc tion’. Thereby a field is created in the Ydirection with the same attributes.

. The function ’Duplicate in another direction’ can be applied simultaneously to several rein- forcement fields, as long as only rectangular (or parallelogram, respectively) fields are se- lected. Hereby, one should note that newly created fields are only different from the original in the swapped bar and laying directions and thus have no effect on the current setting of input directions.

Construction based on elastic reinforcement requirement

Up to now the reinforcement fields were defined without considering the stresses, but purely on the basis of geometrical and detailing considerations. In order to be able to detail based on the elastically required reinforcement contents, first the critical action must be specified, whereby all previously specified limit state specifications are avail able.

state values of reinforcement requirement are calculated.

On the screen the statically required reinforcement areas are displayed graphically ele mentwise as blue lines in the output directions, whereby the thickness of the line in creases with increasing area. In order to see the numerical values, move the mouse pointer over the coloured figures and CEDRUS5 shows the reinforcement areas for the corresponding mouse pointer position in the status line (bottom of window). With the buttons on the left one can also display the requirements for top reinforcement (see above). As expected one needs from the elastic calculation reinforcement above all at the top for the fixed support and below along the free boundary. Now change to the bottom reinforcement again.

To have a better overview, the simula taneous display of the fields and the results for both reinforcement direc tions can be suppressed. Above the register button on the right set the cur rent reinforcement direction to X and the display to ’Show fields in reinforce ment direction’. Thereby only the field in the Xdirection is visible and the re quired reinforcement areas in this direction are now shown as coloured graphics.

Additional reinforcement

Now the question arises whether and where extra reinforcement has to be introduced. This is certainly useful in those areas where the required content is much greater than the minimum reinforcement. Such areas can be displayed by CEDRUS5, provided fields with minimal reinforcement have already been input. For this purpose press first on the button ’Elastic Design’ , whereupon the following dialogue appears:

0.5 m 1.5 m 2 m

D 3 Reinforcement Module Part D Reinforcement and

Since no top reinforcement was input, at this stage no elastic dimensioning is possible. The presentation of the re quired reinforcement contents, how ever, is adjusted, whereby only those zones are highlighted using colours, whose value of bending moment ex ceeds the resistance of the minimum prescribed reinforcement.

. As soon as the button for ’Elastic Design’ is pressed, in the display of the results only those zones are visible whose values exceed the minimum reinforcement. As explained in the follow- ing box, this behaviour can be configured using the Dialogue ’Display Settings’.

Settings for the display of results

The dialogue for changing the display of re sults and reinforcement fields can be opened using the button on the left. As a default value in the Register/Results/ the current rein forcement content (required and present) is selected. In addition the button ’Without fixed and minimum content’ is activated, whereby the fixed prescribed and minimum contents are deducted before display.

On the basis of this presentation and conctructional considerations additional reinforce ment should be specified along the free boundary. Place, therefore, a new reinforce ment field, by first deactivating in the Dialogue Reinforcement Field (Register/Design/) the minimum content, press the button [Create] and then construct as shown the addi tional reinforcement field shown top right.

Top reinforcement

For constructional reasons a top continuous minimum reinforcement should also be specified. One can do this in the same way as for the bottom reinforcement, in that in both directions one provides a reinforcement field with prescribed minimum content. The same can be done more quickly and more easily by first making all fields of the bottom layer visible using the button , selecting both big reinforcement fields (left mouse button:click on the first bar and with SHIFT click on the second bar) and copy this to storage (via Object Menu or CTRL−C). Afterwards change to the top reinforce ment and introduce both fields (via Object Menu ’Paste into active layer’ or CTRL−V).

a variable reinforcement content, this time elastic design is possible. On the screen be sides the required (blue) also the placed reinforcement based on elastic dimensioning (grey) is displayed:

The result obtained of over 94 kgńm3 _{(see figure top left), however, is purely theoretical,}

since in the top reinforcement no gradation was input. For detailing the additional rein forcement in the Xdirection set the visibility according to the buttons on the left and also press the register button ,which draws the bottom reinforcement in a light grey colour (see figure top right). Thereby one can then construct an additional top reinforce ment (without minimum content!) on the bottom one, by pressing in the Dialogue [Create] and then clicking on the bottom right corner of that additional reinforcement and on the top right corner of the plan outline. Analogously define a second reinforce ment field directly next to it.

In the Ydirection input only an additional reinforcement field, which, with a width of approx. 1.5 m, runs along the complete fixed boundary. Then with make first the Ydirection the reinforcement direction, press in the Dialogue [Create] and construct this field with the Graphics Editor (e.g. with absolute coordinates 0,0−7,1.5).

Positioning of the field label

In the construction of a reinforcement field the reinforcing bar and the labelling are automatically positioned. As in the present example (with the additional reinforcement in the Ydirection) this can lead to two bars lying exactly over each other. Since the posi tion of the labelling and thus also of the shown reinforcing bar corresponds to a point (=labelling point), one can move the labelling. This is done as follows:

S Select the last created additional reinforcement. Thereby the field will be shown red. S Right−click the mouse, select the menu ’move label’ and move it to a new position.