bridge software tutorial.ppt

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

TemplateAbutment

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 LARGERLARGER.

1.

2.Repeat for all Repeat for all membersmembers

Time to test your design again….

The truck crosses the bridge without causing a collapse.

Your bridge design is Your bridge design is SUCCESSFULSUCCESSFUL ! !

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.