Bridge Software tutorial

aboundingdriprockUrban and Civil

Nov 29, 2013 (3 years and 11 months ago)

74 views

Open the software and click “close” after reading the tip.


The screen below will come up. You may want to load a sample
bridge design for starters.

You will want to create a new bridge design and then click “OK”


This window breaks down your objective. Read through the design
requirements and the design tip and click next

Here you can adjust the deck elevation. Notice that the
lower the deck elevation is, the more money it will cost.

You may choose either standard abutments or arch abutments.

Then you can choose to add a pier making it a two span bridge. (You
cannot add a pier if you choose the arch abutment. When you’re done,
click “Next”

For starters, select a template that you like. The computer will outline
what the shape of the truss will look like. Click next to continue

Keep in mind that no design is necessarily better than the others. It is
expected that after learning the program you will try different designs
and eventually choose the one you feel is the best.

Fill in your name and click next

Read through the list on how to design the bridge (truss) and click finish

This is the drawing board where you insert joints,
add/delete/adjust members


Deck

Template

Abutment

Roadway

River Valley

Click here to add a joint

Using the mouse cursor add joints

1.

Let’s create some members.

Move cursor to a joint, left click and hold down to
another joint. Continue until it looks like this . . .

2.

Time to test your design….

What Happened?

Our design
FAILED


the load test

Don’t worry we can fix it . . .


Engineering design is an
iterative
process.



Trial
-
and
-
error is always necessary to
achieve a successful product.



If at fist you don’t succeed, then go
“back to the drawing board” and try
again.

Lets return to the
Drawing Board

Click here

Do you notice the appearance of
the structural model has changed?

What’s wrong with these members?

So, were not strong enough

To make the bridge safe, we’ll need to
strengthen the members in
red
.

How can we do that?

We need to make

the members
LARGER
.


1.

2.

Repeat for all members

Time to test your design
again….

The truck crosses the bridge
without causing a collapse.

Your bridge design is
SUCCESSFUL

!

Take a moment to watch the
Load Test Animation.


Note that some of the structural
members turn
red
, while others turn
blue
.


Members that turn
blue
are experiencing
tension
-
they are
being stretched or elongated.


Members that turn
red
are in
compression
-
they are being
squashed or shortened.


The intensity of the color indicates the magnitude of the
member force. Thus the
dark red

diagonal members are
being loaded very close to failure, while the
light blue

bottom chord members are much stronger that they
really need to be.


These observations are important, because they will help
us to optimize our design.

So what’s happening in the animation?


Return to the Drawing Board


Since our bridge didn’t collapse, it is a
successful

design.


Even though, it is successful it’s not
optimal

design,
because it’s much more expensive than it really needs to
be.

How can we reduce the cost of the
bridge without compromising its
safety?


In the previous load test, all five bottom chord members were
color
-
coded with a
light blue
. Light color indicates that, for
each of these members, the tension force was much less than
the strength.

All five of these members can be reduced in size without
compromising the safety of the structure. In fact, you can reduce
their size from
120mm

to
90mm
, and the bridge will still pass the
load test.

What can we do?


Just like before we have to change the size of five members, let’s
use
multiple selections

to speed up the process. Hold down the
Ctrl

key on your keyboard, and then click all five bottom chord
members. All will be selected simultaneously. Now choose
90mm

from the Member Size list, and all five members will be changed to
this size.


Notice that the cost of our design has dropped to
$196,929.06
-
a saving of over
$5,000
. The structure still
passes the load test, so the reduction in cost did not
adversely affect the safety of the structure.



We can still do a lot more to optimize this design. Many
other members can safely be reduced in size.



We can save money by using hollow tubes rather than
solid bars or by using different type of steel


Once you have completed
your design, you need to
print the “Cost Calculations”
and “Load Test Results”


The last thing you will need to
print the design itself.