Lab-6 - Hints from the Lab

Below are the hints from the blackboard in the CadLab during today's session and a couple of extras.

• Save file to desktop in the cadlab to avoid using
• Email it to yourself, or use a flash drive
• Videos online are helpful if the text instructions aren't clear
• If you have only 3-4 letters in your last name - multiply by 20
• Make walls go to 2nd level 
• set "property" before  drawing, but you can change later
• Remember to put on a dimension 
• under the annotate menu
• Not all things in the videos are required for this lab

Lab-6 Which Version(s) of Revit

Question:

I went to the student site to download the software Revit.  While I was on the site i noticed a couple of different Revit programs.  After reading through the lab assignment for CAEE 201, you said to download the Revit Architecture 2012 software, but as an architectural engineering student, would it be wise for me to also download Revit Structure 2012?  Or, is it either too similar to the architecture version or completely unrelated to what I need that it's not worth it?

 

Answer:

If you pursue structural or mechanical engineering within AE you’ll want those programs too. At the moment they’re overkill. Since there’s a new version each year it’s probably not worth getting them till you’ll actually be using them.

Each builds upon a model begun in Revit Architecture and adds features that are unique to those disciplines.

Lab-5 Incremental Costs

Question:

In question 3 are we solving for the incremental cost and payback for option A or option B? I thought it was option B because the incremental cost is provided in the question. However, in question 4 it says "1) You've already calculated the construction "costs" in these two units for the two options. 2) Calculate the incremental "cost" for implementing the "green" strategy in these units". Do the "costs" refer to the CO2 and GHG emissions? And why do we have to calculate the incremental cost for the green option if it's provided in question 3?

Answer:

In Question 3 You are given the amount of rainwater that is saved by using Option-B compared to Option-A.  That allows you to calculate the incremental dollar saving in operation.

In question 4 you are indeed asked to calculated incremental cost in units other than dollars – GHG and energy. 

Please read the other posts to get ideas why calculating costs (and thus paybacks) in multiple units can be worthwhile.

Lab-5 Payback Period

Question:

In step three i got that the you only save $xxxxx a year. That seems like a very trivial amount of money to save for how much the Incremental Construction cost was. This means it would take xxxx some years to see payback money wise. Why would an engineer want to spend so much more money on this? Especially considering that it was not even any greener CO2 wise to build.

Answer:

You’re discovering why engineers perform these calculations.  It’s as important to determine what makes does not make “sense” as what does. 

What’s also important, and a major reason for this lab, is to see that using different measures of calculating the payback period can produce quite different results.

Finally, often dollar calculations of costs and benefits to the owner do not always take into account the societal costs of various projects.

Lab-5 Avoided Annual Cost

Question:

I am still confused on the section of question 4 about the avoided annual cost. What information is used to calculate these values?

Answer:

The logic of avoided dollar cost is that the “green” construction option reduces the amount of water that runs off the property.  Because the municipality charges to treat the sewer water, reducing the amount the runs off saves on the fees that the property owner pays each year.

You are given the information to calculate the average annual avoided water runoff and thus to calculate the dollars that the property owner doesn’t have to pay in fees.

Lab-5 Memo Grading Criteria

Question:

In the memo grading section on the lab, it asks us to talk about the 'Relation to site visit.' Is this referring to the eiolca.com website in terms of how the data we got from it was important, or am I misunderstanding this?

Answer:

Oops.  You’ve caught a carryover between two versions of the lab.  This “site visit” criteria is inappropriate this term (it was valid last spring) and the graders will ignore it, distributing the points as follows

• Purpose of the lab - [7 pts]
• Implications - [4 pts]
• Limitations - [4 pts]

Lab-5 Incremental Cost

Questions:

1. about Question 4. Is "Incremental 'cost'" Option B minus Option A?
2. Is the avoided annual cost the values given in the calculation instructions? If we did our calculations right should our "inremental cost" be the same?

Answers:

1. Yes
2. The incremental cost referred to is the construction incremental cost – a one-time cost which you are given – $150,000 (as I announced in class don’t use the $800K).  You are being asked to calculate the annual dollar value of the water that doesn’t run off the site.  It’s not the same thing as the construction cost.

Lab-5 Material Choice

Question:

“for question one it asks for concrete pavement but in table 3 there in not a category for it there is asphalt concrete, porous concrete, and curb concrete, which one of these do u want use to use?”

Response:

When you look in the “Assumed Raw Material” column you’ll see that “Concrete” is listed as the choice to “Concrete Curb with openings”.  That’s the line that doesn’t have a modifier for “concrete”.  Use it.

Lab-5–Why is Option-B Green?

Question:

I have a conceptual question from lab 5. In question 2, why does option B, which is the environmentally friendly option, have more carbon emissions than option A?

Answer:

Your question gets at the heart of the kind of questions engineers have the tools to answer.  The presumption is that if you “spend” a bit more at the beginning you’ll accrue savings over the life of the project that justify the extra initial “cost”?  We can measure that “cost” in many ways:  $, Energy, GHG, radiation….. 

What we can do, and indeed you’re doing it in this assignment, is evaluate the extra initial costs and the savings, and then relate them (in this case “payback”) to see whether the option is “worthwhile.”

Lab-5 LCA Analysis–Friday Availability

An Excel spreadsheet for the lab this Friday will be mounted early Friday (10/21/2011) morning before the 10:00 lab.  We’re checking the formatting and calculations to be sure that we’re giving you as well-tested a lab as possible.  Our apologies for the lateness.

Lab-4 Truck Weight

Question:

Item 6 in the instructions tells you that W is the weight of the truck, which you can calculate at this point, however the next question asks you to measure the weight of the truck. Is it asking you to do this again? Is the 'W' in 6 the same as the 'W' in 7?

Response:

Please read the text of the question carefully.  #6 does not address the absolute weight of the truck.

Lab-4 Graphing Data

Question:

I read the blog and it says i should graph the sensors data over time, i am having trouble with this is there any place i could find excel help?

Response:

In Excel-2010(PC) if you open Help (File Menu “Help”  OR F1) and search for “graph” the second entry is “Create a chart from start to finish”.  That help item (and others) will help you graph the data provided.  Note that the first column in the data is time.

You can also ask for help in Korman.

Lab-4 Appropriate Drawing

Question:

“the sketches of the bridge that are in VBB have two pages 11 and 12 with different measurements for the top chord where the sensors were placed, which pages measurments should i use?”

Answer:

I checked the smaller PDF that has only the drawings - “Tacony-Palymra Drawings”.  In that set p.11 is entitled “Approach Span Details”.  P.12 is entitled “Truss Spans Stress Sheet”.  You need to decide, based on where the measurements were taken on the bridge, which of these is appropriate.

Lab-4 Weight Calculation

Question:

I'm having a problem with the weight i am getting for the truck, and after talking to two other people they were also having problems with the weight as well. Every time i do the calculations my weight comes out to something 10^9. I am pretty sure that there is no way that the vehicle could weigh that much. I used the maximum strain on the graph of sensor 2, as well as the average for all of the sensors and still got a very large number that seems impossible. How would i take into consideration the weight of the bridge so i can find the mass of the truck only?

Response:

You’re having a problem that is quite common in the real world, and why it’s important to have a “cross-check” on the expected answer.  I’m putting several comments below that may help.

• Very often this kind of problem arises from a units issue.  Often it has to do with not being consistent (and converting where necessary) between inches and feet.
• Later Addition – Mr. DeVitis reviewed this response and agreed that the problem was probably units.  He says “This is certainly a unit issue. The measurements provided are in micro-strain [ue] and need to be converted to strain [e]. Accounting for this, his answer would be ~10,000lbs which is pretty close to the xxxxx lbs I calculated” (JEM deleted his exact answer.
• See the other blog posts for comments about the sensor location
• You should not need to take the weight of the bridge into consideration since the strain measurements start with the bridge already in place.

Lab-4 Calculation Questions

Question 1:

Where can we find the dimensional data to calculate the cross sectional area for the bride? We looked through the Tacony Palmyra drawing saved in the 'resources' folder and did not see it. We saw some things that look sort of correct but it is a bit ambiguous which to use.

Response:

This is determined by the location of the member on the bridge.  It’s why you need to know where you were.  See the other blog posts.

Question 2:

It seems to me that the average of the sensor data is the best to use because it will have the least variation, however my friend thinks that the top member is the best because it has the direct tension forces from the truck. Does it matter which sensors we use?

Response:

Both of you are right.  You can use either without problem.  Each provides advantages.  You might discuss them in the “sources of error” question.

Lab-4 Measurement Location

I’ve received several questions relating to where the measurements were taken.  Here’s a representative one:

Question:

“In the lab description we are given an example of how to calculate the cross-sectional area of the top chord. Are we supposed to know which member the measurements were taken at? The excel spreadsheet has "(ue)" next to every sensor's name. Does that have something to do with the location? “

Answer:

You were asked during the field trip to be careful to locate where on the bridge the measurements were taken, and warned that it wasn’t as simple as it might seem.  Here are several hints to help:

• For your purposes you can ignore the “ue” – you know that the sensors were all on the upper “flange” member of the truss.
• It’s OK to ask your classmates where the measurements were taken – give them credit in your lab report if you didn’t determine the location yourself.
• Refer to the drawings that are on the VBB site for assistance.  Once you’ve located the measurement location you’ll also be able to determine the components of the truss member at that location as Dr. Moon explained.
• The three truss spans are mirror images of each other.  Only one set is drawn on the plans for that reason.

Lab-4 Requirements

Question:

“While looking over the lab I noticed that there were two word documents that explain what to do for this lab.  However I noticed that they differ in the questions they ask, one is more detailed than the other, and I wanted to know what questions exactly are we looking to answer? 

• Is it the contents document or the more detailed lab description? 
• Also in what form is this lab to be submitted?  Is it a written report? Or are we to write out our calculations and hand them in in class?”

Answers:

1. The instructions in the document “T-P Lab Description 2011-10-11” are the ones that govern the lab requirements.  The “Data Explanation” document is meant to be an aid.  The questions in that document are ones that should assist in meeting the main requirements.
1. The graders will give you up to 5 points  extra credit (up to a maximum of 100 points for the lab) for answering the “Bonus” question in the “Data Explanation” document.
2. You are to submit the lab in electronic form to VistaBB.  I heartily recommend using Excel, but you may use Word or you may scan to PDF hand prepared documents (but they must be readily legible).

Lab-4–How to Start–Determining Truck Strain

Question:

“I am confused on how to start. The data given to us is about the sensor and time.”

Answer:

Please look at Prof. Moon’s description of the lab.  You’ll see in item #5 that you need to know the maximum strain.  In order to calculate that maximum strain you need to look at it over time to see an “average” when there isn’t a truck and then find the maximum when there is a truck.

Hint:

If you plot the strain (individual or average) over time using Excel you’ll almost certainly see a negative peak as well as the average that will allow you to determine strain.

L4 - Data from Bridge Visit Added to Lab 4 Assignment Submit

10/15/2011 5:50 PM Three additional files were added to the assignment that give the strain data, a picture of the truck that produced the strain data, and an explanation of what the data is and how to handle it.

Lab-3 Question about Piers

Question:

I had a question about Quest 4 & 5. Since we have two piers that make up the one pier which is being impacted by the tanker. Would you have to multiply the height by 2 to account for both piers when calculating for the Moment? I assumed that it would only have be just the height of the first pier since thats the one the tanker is actually making contact with. Does the same apply for the section modulus? would the section modulus need to be multiplied by two to take into amount there are two piers?

Answer – Prof. Dasaro:

No. You don't multiply the height of the piers by 2. They are what they are. What you adjust is the stiffness of the two-pier system by increasing the given k value by a factor of two. This is because two piers share the tanker load and the given k value is the stiffness for only one pier. You do that in Question 2.

Lab-3 File Reposted Again

Several students have written saying that the Excel file for Lab-3 wouldn’t open.  VistaBB apparently corrupted it.  I’ve uploaded and tested a clean version that should be OK.  The filename ends in “v2”  10/13/2011 7:10AM.

Prof. Dasaro’s associated lab slides are in the “Resources” folder in “Lecture Notes”

Jim Mitchell

Lab-3 Question-6 (revised)

Question:

“I am confused about Question 6 in Lab 3. When performing the back calculations, how is the value for Stage 2 deflection determined? Since, the equation is x Stage 2=(KE-PE)/P and KE is unknown, I do not see how it can be calculated. Should I use the same value I came up with in Question 2? Do I assume we don't want any Stage 2 deflection and use 0?”

Response from Prof. Dasaro

“I wanted the students to think a little.   That's why I did this” after a set of calculations that essentially recreate the lecture example.

He advises that you consider in what “region” of the stress-strain curve this stress in the pier would be located.  That will tell you something about whether you need to know the KE or not.

You’ll still need to think about what steps you need to take, but hopefully this hint will enable you to do so.

10/11/2011 07:40AM Addition from Prof. Dasaro

"Question 5 yields the bending stress in the bridge pier at the onset of unrestrained plastic flow. Compare this stress value against the 3,000 psi limitation in question 6."

Lab-3 Excel File Problem

Several students reported problems opening the file for Lab-3 (Tanker hits Bridge).  I checked and found that somehow the file had been corrupted.  I’ve uploaded a repaired version as of 9:00PM Sunday night.

Soils Lab Questions

Question

I am aware of how to calculate the total vertical stress at the points, although I am not quite sure what needs to be put in the depth column. Is it the thickness of the layer, the depth at which you first hit the layer, or the depth to which the layer stretches?

Answer:

The depth is the absolute depth below the surface at which you’re calculating the pressure – positive going down from the surface.

 

Question

I also was wondering how to go about calculating the pore pressure.

 

Answer

Dr. Sjoblom explained how to calculate the pore pressure in the lecture. His notes are online in the folder:  Resources/Lecture Notes.

Lab Template attached to Submit

For the rest of the term the files associated with the labs will be attached to the “submit” link in VistaBB. 

To get the template and any associated files (e.g. TA notes)

• Click on the “submit” link for that lab  e.g. “L3 submit”
• Download the files you need by click on them
• CANCEL the submission – you’ll come back to it once you’ve completed the lab.

Discussions–Grader’s Advice

While grading the discussions, I am noticing that the majority of the students are simply summarizing what their chosen articles say rather than weighing their personal input into the discussion thread. The purpose of these assignments to identify what the student finds the most interesting and what they are confused about, rather than reiterating the information contained in the articles? If I wanted to know what the articles said, I would just read them myself.

The interesting/confusing discussions should also be kept within the realm of the weekly topic. For example, being interested in the color of a building when looking at the structural engineering aspect is not relevant.

Also, I am finding that most students are not addressing the weekly special question directly. We suggest the following format to the class? This would make grading the discussions much easier, as well as increase the grades for the students.

First Article Title, Author, Hyperlink, etc.

• * A very brief (2-3 sentences) identification of the article’s subject
• * 1 paragraph (3-4 sentences) about what you found the most interesting about the article
• * 1 paragraph (3-4 sentences) about what you found the most confusing about the article

Second Article Title, Author, Hyperlink, etc.

• * A very brief (2-3 sentences) identification of the article’s subject
• * 1 paragraph (3-4 sentences) about what you found the most interesting about the article
• * 1 paragraph (3-4 sentences) about what you found the most confusing about the article

Special Question

• * 3-4 sentences directly addressing the weekly question