Week-10 Presentations - Why We're Not Making Them

Question:

Why don't we have a presentation time for our project? I don't mind that we don't have to do that extra work, but I'm curious about your reasoning on this decision.

Response:

My belief when putting together this course was that the week-10 presentations didn't make sense for our sections for the following reasons:

• Everybody is doing the same thing in our sections, whereas other sections have more varied projects.  I felt it would become boring to everyone to hear the same issues addressed many times.
• I asked a considerable effort of you in putting together the weekly posts as well as the assignments.  Making the last week a lighter load seemed like a good idea.

I'd be glad to hear from the class if you think adding the presentations another time would be beneficial.

Jim Mitchell

Refining Bridge Design

I've had two good questions about refining your bridge designs that may be of general interest.

Q1 - Why does an "X" type arrangement fail when using the Hopkins "Bridge Designer".

Response:

Probably the best answer is that you have created a "redundant" structure with an "X".  You can test that by removing one leg of the X and probably it will work as in the example above.  If you add the member from the lower left to the center of square so you have a complete "X" Bridge Designer won't calculate it because you have an unnecessary or "redundant" member.

Q2 - Additional Analysis

Throughout the project, I have been replicating the Knex bridge on WPBD as an extra load test. But thinking about what you said today after lab, I realize that's not the best way to test our truss. What at-home methods do you suggest would be best to see if the truss is stable?

Response:

Unfortunately you're running up against the limits of the tools you will understand in your first year.  There are indeed many tools for additional analysis and testing, but to use them effectively you need the knowledge that you'll gain in your more advanced courses.  WPBD and Bridge Designer have to make simplifying assumptions that your real bridges violate.  Let's hope this is your incentive to continue learning.

About This Blog

We'll use this blog as home base for all information related to our two sections of ENGR-103.  It has all the assignment information, grading information that you’ll need.  We’ll also use it to post Official announcements and answer questions that are raised throughout this term. 

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