A blue line in the Setup Window represents a continuous beam. Thirty-three cyan circles on it are the nodes of this FEM model. Namely a continuous beam is going to be modeled by 32 finite elements in this program.
When you Left Click along this blue line,
a small window as is in Fig. will appear.
And the node just left of your mouse pointer is expressed by a red circle.
You can specify the geometrical boundary condition at this node.
Except two end nodes, you can specify a displacement-fixed,
a rotation-fixed or a spring-supported condition at any nodes.
At the ends, a fixed condition can also be given.
At the spring-supported node, you must specify its linear spring
constant
by a non-dimensional value as
, where
is the basic bending rigidity and
is an element length.
After clicking a button of specifications, you click Set
to give the condition to the node.
In the Setup Window as shown in Fig.,
indicates a simple support; two vertical bars
represents a non-rotational support; and one vertical bar
at the ends is a fixed end.
One vertical bar beneath a node indicates the spring-support.
Also you can insert hinges in the span.
If you want to insert only a hinge without support,
first hit the Reset button.
Then check the last item in this small window
and click Set button.
A hinge cannot be inserted at the non-rotational support
and at the node where a concentrated moment force is applied.
The node where you want to specify BC's can be chosen by
scroll button which is located near the mouse pointer in Fig.
or by entering number in the input window just to the left of the scroll
button.
The left-most node is here named as the 1st node.
Such chosen node is expressed by a red circle along the blue line.
You can change the condition of a node as many times as you like.
If you click Reset button, then the specified
node becomes free of support.
You can continue these settings until you close this small window
by clicking
.
The main window cannot be accessed while such a small window is open.
In any elements, arbitrary values of rigidity can be given.
Since this program solves a non-dimensional stiffness equation,
the input value is a ratio to the basic bending rigidity, say
.
Right Click along the blue line in the Setup Window
opens a small window as is shown in Fig.
.
Then the node near the mouse pointer is expressed by a red circle, and
a node between that node and the right end is indicated by a blue circle.
You can specify the bending rigidity between these
red and blue circles.
You can change two nodes by the scroll button or direct input of
the node number.
Once you choose the span of the same bending rigidity,
give a positive real number in the input window of the rigidity ratio.
After that, typing Enter key sets that ratio.
In an example shown in Fig.,
the ratio is given by `3.'
You can continue any settings until you close this small window.
Magnitudes of these ratios are approximately shown
by the width of a green band (indicated by a mouse
pointer in Fig.
) below the blue line
in the Setup Window.
Left Click slightly above the blue line
in the Setup Window will show a small window
as is shown in Fig..
Within this small window you may give concentrated loads.
Fist choose the node where such loads are given, and
input the values of the shear force
and/or
the bending moment
.
The shear force is positive to the downward direction, while
the bending moment is positive to the anti-clockwise direction.
Both of them must be specified by non-dimensional quantities
such as
and
which are
non-dimensionalized by the element length
and the
basic bending rigidity
.
The element length
is a distance of the adjoining nodes
and is one thirty-second of the total length of
the blue line in the Setup Window.
Clicking Set specifies the loading condition at the node. A vertical bar above the blue line in the Setup Window indicates a concentrated shear force, while a circle is an applied moment. These magnitudes (ratio) are approximately expressed by the length or radius of these symbols respectively. While the directions of these forces are not shown in this window, the Results Window will show them after calculations.
Right Click slightly above the blue line
in the Setup Window will open a small window
as is shown in Fig..
Just like in the case where the rigidity is specified,
two nodes in red and blue appear.
You can put a uniformly distributed load
between these nodes.
The load is positive in the downward direction.
After choosing nodes, you must enter
its non-dimensional value of
and
hit Enter.
Then the magnitude and location are approximately shown by a magenta band
in the Setup Window.