Coma: Estado de inconciencia en el que la persona no responde inclusive a estímulos dolorosos

3 6.0 3.5 0.0 ; 4 6.0 0.0 0.0 5 6.0 0.0 6.0 ; 6 6.0 3.5 6.0 MEMBER INCIDENCE 1 1 2 ; 2 2 3 ; 3 3 4 ; 4 5 6 ; 5 3 6 Steps:

1. We selected the Add Beam option earlier to enable us to add beams and columns to create the structure. This initiates a grid in the main drawing area as shown below. The directions of the global axes (X, Y, Z) are represented in the icon in the lower left hand corner of the drawing area.

2. A Snap Node/Beam dialog box also appears in the data area on the right side of the screen. In our structure, the segment consisting of members 1 to 3, and nodes 1 to 4, happens to lie in the X-Y plane. So, in this dialog box, let us keep X-Y as the Plane of the grid. The size of the model that can be drawn at any time is controlled by the number of Construction Lines to the left and right of the origin of axes, and the Spacing between adjacent construction lines. By setting 12 as the number of lines to the right of the origin along X,

7 above the origin along Y, and a spacing of 0.5 meter between

lines along both X and Y (see figure below) we can draw a frame 6m X 3.5m, adequate for our segment. Please note that these settings are only a starting grid setting, to enable us to start drawing the structure, and they do not restrict our overall model to those limits.

3. To start creating the nodes, let us first activate the Snap

Node/Beam button by clicking on it. Then, with the help of the

mouse, click at the origin (0, 0) to create the first node.

Figure 2. 11

4. In a similar fashion, click on the following points to create nodes and automatically join successive nodes by beam members.

(0, 3.5), (6, 3.5) and (6, 0)

The exact location of the mouse arrow can be monitored on the status bar located at the bottom of the window where the X, Y, and Z coordinates of the current cursor position are continuously updated.

When steps 1 to 4 are completed, the frame will be displayed in the drawing area as shown below.

5. At this point, let us remove the grid display from the structure. To do that, click on the Close button in the Snap Node/Beam dialog box.

The grid will now be removed and the structure in the main window should resemble the figure shown below.

Figure 2. 14

6. It is very important that we save our work often, to avoid loss of data and protect our investment of time and effort against power interruptions, system problems, or other unforeseen events. To save the file, pull down the File menu and select the Save command.

Switching on node and beam labels

7. Node and beam labels are a way of identifying the entities we have drawn on the screen. In order to display the node and beam

numbers, right click anywhere in the drawing area. In the pop-up

menu that appears, choose Labels. Alternatively, one may access this option by selecting the View menu followed by the Structure

Diagrams option from the top menu bar, and the Labels tab of the

dialog box that comes up.

8. In the Diagrams dialog box that appears, turn the Node Numbers and Beam Numbers on and then click on OK.

The following figure illustrates the node and beam numbers displayed on the structure. The structure in the main window should resemble the figure shown below.

Figure 2. 17

If you are feeling adventurous, here is a small exercise for you. Change the font of the node/beam labels by going to the View menu and selecting the Options command, and then selecting the

appropriate tab (Node Labels / Beam labels) from the Options dialog box.

9. Examining the structure shown in section 2.2 of this tutorial, it can be seen that members 4 and 5 can be easily generated if we could first create a copy of members 1 and 2 and then rotate those copied units about a vertical line passing through the point (6, 0, 0, that is, node 4) by 90 degrees. Fortunately, such a facility does exist which can be executed in a single step. It is called Circular Repeat and is available under the Geometry menu.

First, select members 1 and 2 using the Beams Cursor . (Please refer to the ‘Frequently Performed Tasks’ section at the end of this manual to learn more about selecting members.)

10. Then, either click on the Circular Repeat icon from the appropriate toolbar, or, go to the Geometry | Circular Repeat menu option as shown below.

11. In the 3D Circular dialog box that comes up, specify the Axis of

Rotation as Y, Total Angle as 90 degrees, No. of Steps as 1 and the

vertical line as passing through Node 4. Instead of specifying as passing through Node 4, one may also specify the X and Z co-

ordinates as 6 and 0 respectively. Leave the Link Steps box

unchecked and click on the OK button.

After completing the circular repeat procedure, the model will look as shown below.

Before

Figure 2. 20

After

Figure 2. 21

If any of the members are presently selected, let us unselect them by clicking anywhere else in the drawing area. Then, let us once again save the work by pulling down the File menu and selecting the Save command.

2.6.2 Changing the input units of length

As a matter of convenience, for specifying member properties for our structure, it is simpler if our length units are millimeter instead of meter. This will require changing the current length units of input. The commands to be generated are:

UNIT MMS KN