# 6 minute solutions vs actual SE I exam?



## buening (Oct 14, 2008)

Can anyone that has recently taken the SE I exam comment on the degree of difficulty of the actual exam compared to the questions on the "6 minute solutions for the Structural I exam" booklet by "the other board"? I know the sample NCEES exam is supposed to be pretty close, but I was working on the problems from the 6 minute solutions and most of them seemed pretty tough and time consuming. Those problems have me concerned


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## Jennifer (Oct 14, 2008)

buening said:


> Can anyone that has recently taken the SE I exam comment on the degree of difficulty of the actual exam compared to the questions on the "6 minute solutions for the Structural I exam" booklet by "the other board"? I know the sample NCEES exam is supposed to be pretty close, but I was working on the problems from the 6 minute solutions and most of them seemed pretty tough and time consuming. Those problems have me concerned


Honestly, I felt that the NCEES exam was way too easy compared to April's exam. I didn't go through the whole 6 min solutions before that one, but I'm using it this time to prepare. It's more difficult, but I'm thinking that's a better prep.


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## buening (Oct 14, 2008)

Jennifer said:


> Honestly, I felt that the NCEES exam was way too easy compared to April's exam. I didn't go through the whole 6 min solutions before that one, but I'm using it this time to prepare. It's more difficult, but I'm thinking that's a better prep.


Good to hear from someone that can relate the three. I will be doing the NCEES practice exam this weekend, but these 6 min solutions are pretty darn tuff. Some of the solutions fill a page and a half. I'm lucky to just copy the solutions in 6 minutes, let alone look up some of the formulas and actually think for a second LOL.

Also, I've noticed that there are alot of design and analysis problems in this 6 minute solutions booklet that call out an unspecified "compressive load of 320k and moment of 200k-ft". One example would be a moment resisting base plate with anchor bolts on Problem #45. They don't state if these loads and moments are factored, yet all design should be done with LRFD according to NCEES (except masonry). The anchor bolt design of this base plate problem finds the tensile force on the anchor bolt and then pulls the ASD tensile strength of a 1" bolt from the AISC tables. The LRFD tensile strength is enough that a 7/8" bolt could be used, but that goes back to if these loads given are factored or service. These are some of the minor things that keep tripping me up. There are other problems that this has occurred. I'm hoping the NCEES exam is a bit more specific on what load is given, because I don't feel like the ASD tensile strength should have been used for the anchor bolt problem. Have you hit this problem yet?


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## Jennifer (Oct 14, 2008)

buening said:


> Good to hear from someone that can relate the three. I will be doing the NCEES practice exam this weekend, but these 6 min solutions are pretty darn tuff. Some of the solutions fill a page and a half. I'm lucky to just copy the solutions in 6 minutes, let alone look up some of the formulas and actually think for a second LOL.
> 
> Also, I've noticed that there are alot of design and analysis problems in this 6 minute solutions booklet that call out an unspecified "compressive load of 320k and moment of 200k-ft". One example would be a moment resisting base plate with anchor bolts on Problem #45. They don't state if these loads and moments are factored, yet all design should be done with LRFD according to NCEES (except masonry). The anchor bolt design of this base plate problem finds the tensile force on the anchor bolt and then pulls the ASD tensile strength of a 1" bolt from the AISC tables. The LRFD tensile strength is enough that a 7/8" bolt could be used, but that goes back to if these loads given are factored or service. These are some of the minor things that keep tripping me up. There are other problems that this has occurred. I'm hoping the NCEES exam is a bit more specific on what load is given, because I don't feel like the ASD tensile strength should have been used for the anchor bolt problem. Have you hit this problem yet?


I'll look into that one and let you know what I find out. Make sure to check the errata online. There are definately mistakes. I would think the wording is going to be more like the NCEES problems, so hopefully those make more sense. I don't have that in front of me right now.


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## buening (Oct 14, 2008)

Jennifer said:


> I'll look into that one and let you know what I find out. Make sure to check the errata online. There are definately mistakes. I would think the wording is going to be more like the NCEES problems, so hopefully those make more sense. I don't have that in front of me right now.



yeah I have the latest and greatest edition of the 6 minute solutions book, and there is only one error shown in the errata. I've found a few that I'll be submitting as well. The more I dig into this book the more ASD steel problems are done. There are numerous weld and bolted connection designs where the solutions starts out saying "Using ASD....." I'm just finishing up the steel section, which wasn't horrible unless you count my designs in LRFD that end up different than the results they get from ASD :smileyballs:


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## SE-III (Oct 15, 2008)

Please confirm if out of the following two editions of 6 minutes solutions the second one is good for SE-I and SE-II exams. While the first one is only good for Civil/Structural PE exam.

1) 6 Minute Solutions for Civil PE Exam - Structural Problems

2) 6 Minute Solutions for Structural PE - Exam Problems


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## vane_gator (Oct 15, 2008)

I've looked at both the SE specific and Civil/Structural specific 6 min solutions. They're almost identical


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## kevo_55 (Oct 15, 2008)

^^ I 2nd the comment.

Only buy one of them. They really are the same, except in a different order.


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## buening (Oct 15, 2008)

I own the 2nd edition of the SE I book (1st printing, which I believe is the only one out), so my above comments about problems in ASD Steel are valid to the newest edition. I don't believe either book goes in depth enough to help prepare for the SE II exam. Only the NCEES SEII practice exam will help there, and that is the only reference that I know of that goes in depth enough for the SEII exam.


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## Jennifer (Oct 15, 2008)

buening said:


> I own the 2nd edition of the SE I book (1st printing, which I believe is the only one out), so my above comments about problems in ASD Steel are valid to the newest edition.


I think they give you answer choices for both ASD and LRFD since it lets you do both on the exam. So, if you work it LRFD or ASD, it doesn't matter. Isn't it that way in the NCEES sample book?


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## kevo_55 (Oct 15, 2008)

Jennifer,

You're right. You'll have one set of answers for ASD and then another set for LRFD.


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## buening (Oct 15, 2008)

Ah, see I was not aware of that! I had heard ones in the past gave two answers (in LRFD and ASD), but I could have sworn that they eliminated the ASD answers completely. I could be wrong though


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## kevo_55 (Oct 15, 2008)

^^ Well, just remember that this is for steel only though.

Another way to think about it is that with both sets of answers, only one will be correct in the ASD set and one will be correct in the LRFD set. If the correct answer happens to be A in LRFD, then the correct answer will be A in ASD as well.

If you have the time, it might be a nice way to double check your answers.


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## buening (Oct 15, 2008)

kevo_55 said:


> If you have the time.....


:screwloose: Yeah, because time is so abundant on this exam :Locolaugh: Good call though! I've found that my 6 minute problems are taking 12 minutes to solve, sooooo time has become my challenge on this exam. Only 8 days and counting!!! I think my caffiene is wearing off, back to the coffee pot!


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## ODB_PE (Oct 15, 2008)

:2cents:

The majority of six-minute solutions are much more difficult than what you will see on the exam.

Therefore, if you get very comfortable with the six-minute solutions, and can use them as a reference to direct you to the proper codes, etc., you will be in good shape with the exam.

JMHO


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## buening (Oct 15, 2008)

ODB_PE said:


> :2cents:
> The majority of six-minute solutions are much more difficult than what you will see on the exam.
> 
> Therefore, if you get very comfortable with the six-minute solutions, and can use them as a reference to direct you to the proper codes, etc., you will be in good shape with the exam.
> ...


......unless you are like me and are taking the exam in Illinois. The only material allowed in the IL exam are codes and textbooks. No "the other board" reference manuals or books with solutions or example problems :smileyballs:

Glad to hear most people agree the 6 min problems are more difficult than the ones on the exam. Before I started this thread I was kind of freaking out with the difficulty of those problems.


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## Jennifer (Oct 15, 2008)

buening said:


> Yeah, because time is so abundant on this exam Good call though! I've found that my 6 minute problems are taking 12 minutes to solve, sooooo time has become my challenge on this exam. Only 8 days and counting!!! I think my caffiene is wearing off, back to the coffee pot!


Time wise...I didn't feel like it was a problem last time...especially in the morning part...not exactly abundant, but enough at least. I handled it this way...

1st pass - answer everything I just knew how to do with out thinking twice about it. Anything that was taking me too long to figure out how to approach it, I dog eared the page and moved on. Then, the next pass, I did the ones I knew I could find easily in my books. Then, last pass was to search for anything I was clueless on. In the AM portion, I got a few more questions answered "confidently" and a few that I was able to make more educated guesses. PM portion...I couldn't find any thing helpful on the last pass, but I at least had a chance to try. I took the last 5 minutes or so of each exam to make sure I had a bubble filled in each answer and that it was the one I wanted filled according to my exam book.


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## SE-III (Oct 15, 2008)

Jennifer said:


> Time wise...I didn't feel like it was a problem last time...especially in the morning part...not exactly abundant, but enough at least. I handled it this way...
> 1st pass - answer everything I just knew how to do with out thinking twice about it. Anything that was taking me too long to figure out how to approach it, I dog eared the page and moved on. Then, the next pass, I did the ones I knew I could find easily in my books. Then, last pass was to search for anything I was clueless on. In the AM portion, I got a few more questions answered "confidently" and a few that I was able to make more educated guesses. PM portion...I couldn't find any thing helpful on the last pass, but I at least had a chance to try. I took the last 5 minutes or so of each exam to make sure I had a bubble filled in each answer and that it was the one I wanted filled according to my exam book.


In SE-I Exam, is the AM portion easier than the PM portion (like it is the case in Civil/Structural PE exam)? Is it a big different in difficulty level between two sessions?


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## Jennifer (Oct 15, 2008)

I felt like it was a little easier, but not a huge difference.


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## buening (Oct 15, 2008)

SE-III said:


> In SE-I Exam, is the AM portion easier than the PM portion (like it is the case in Civil/Structural PE exam)? Is it a big different in difficulty level between two sessions?


Which PM will you be taking, the bridges or buildings? This will be my first time taking the SE I and II, but the morning session is completely different for a bridge guy. I would venture to guess that the PM portion is much more difficult because of the depth involved, but the AM portion has a lot more to study and refresh on if you are a bridge person.


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## Jennifer (Oct 15, 2008)

buening said:


> Which PM will you be taking, the bridges or buildings? This will be my first time taking the SE I and II, but the morning session is completely different for a bridge guy. I would venture to guess that the PM portion is much more difficult because of the depth involved, but the AM portion has a lot more to study and refresh on if you are a bridge person.


SE1 doesn't give you a choice. You answer all the questions...buildings and bridges.


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## buening (Oct 15, 2008)

Jennifer said:


> SE1 doesn't give you a choice. You answer all the questions...buildings and bridges.


Sorry, I meant to say what he was choosing for the SE II not the PM portion.


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## kevo_55 (Oct 15, 2008)

buening,

The SEII only gives you a choice in the morning. Your PM exam must follow up with your AM exam.

Example, for the AM you can choose either the building problems or the bridge problems. For the PM exam, you must continue on with whatever you did for the AM portion.

So, if you do buildings for the AM you must do the building problems for the PM exam.


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## Jennifer (Oct 16, 2008)

buening said:


> Good to hear from someone that can relate the three. I will be doing the NCEES practice exam this weekend, but these 6 min solutions are pretty darn tuff. Some of the solutions fill a page and a half. I'm lucky to just copy the solutions in 6 minutes, let alone look up some of the formulas and actually think for a second LOL.
> 
> Also, I've noticed that there are alot of design and analysis problems in this 6 minute solutions booklet that call out an unspecified "compressive load of 320k and moment of 200k-ft". One example would be a moment resisting base plate with anchor bolts on Problem #45. They don't state if these loads and moments are factored, yet all design should be done with LRFD according to NCEES (except masonry). The anchor bolt design of this base plate problem finds the tensile force on the anchor bolt and then pulls the ASD tensile strength of a 1" bolt from the AISC tables. The LRFD tensile strength is enough that a 7/8" bolt could be used, but that goes back to if these loads given are factored or service. These are some of the minor things that keep tripping me up. There are other problems that this has occurred. I'm hoping the NCEES exam is a bit more specific on what load is given, because I don't feel like the ASD tensile strength should have been used for the anchor bolt problem. Have you hit this problem yet?


I did this problem last night and totally missed that it was wrong...I was looking in the back to do it, though.

My thoughts...since it's telling you to design with LRFD and giving you the loads, not dead and live, it's safe to assume they are already factored.

As far as the design methods...look at the NCEES code list. http://www.ncees.org/exams/professional/pe...n_standards.pdf

You can use ASD or LRFD for steel design. Masonry is ASD except for slender walls. I'm not sure about Wood, but it's traditionally ASD, the LRFD is new, so I would use ASD there, but that's how I learned it. I think everything else is LRFD.


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## buening (Oct 16, 2008)

It does say that ASD or LRFD can be used with steel at the bottom of the structural standards. I must have missed that!


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## Jennifer (Oct 16, 2008)

buening said:


> It does say that ASD or LRFD can be used with steel at the bottom of the structural standards. I must have missed that!


Hey, did you find a mistake on problem #23 in their calculation?


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## buening (Oct 16, 2008)

Nah, I looked at that problem and decided that would be one I'd save for last and would take entirely too long. I know how to do the conjugate beam method, but when it ends up with parabolic loadings is when I decide it would take longer than 6 minutes :Locolaugh: I hope the loading of the beam is a bit more simple on the actual exam.

What was the error?


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## buening (Oct 16, 2008)

There is also a problem towards the end of the masonry section that requires a column interaction table for masonry columns. These aren't even in the SERM, but the solution states to look into the Masonry Designers Guide for the table. It's problems like that to where if you don't have the table, you are screwed because it'd be a half hour calculation.


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## Jennifer (Oct 16, 2008)

buening said:


> Nah, I looked at that problem and decided that would be one I'd save for last and would take entirely too long. I know how to do the conjugate beam method, but when it ends up with parabolic loadings is when I decide it would take longer than 6 minutes :Locolaugh: I hope the loading of the beam is a bit more simple on the actual exam.
> 
> What was the error?


Actually...the conjugate beam thing wasn't as bad as I expected. I forgot all about how to do it, but it's just drawing the moment diagram and then a little more on it. Basically...I found the calculation for Rl to be calced wrong...I have no problem with the numbers added together, but I got 1038/EI not 1082/EI


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## Jennifer (Oct 16, 2008)

buening said:


> There is also a problem towards the end of the masonry section that requires a column interaction table for masonry columns. These aren't even in the SERM, but the solution states to look into the Masonry Designers Guide for the table. It's problems like that to where if you don't have the table, you are screwed because it'd be a half hour calculation.


Guess I havent' done that yet...I'm at 46, but I've skipped some in the around that conjugate beam thing...the fixed end moments ones...


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## Jennifer (Oct 20, 2008)

Ok, Buening, have you worked Problem #55? I think the solution is wrong here, too. I think it should be 65.2, not 60. The AASHTO says to take 12x the slab thickness and add half the girder flange width. Does that sound right to you?


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## buening (Oct 20, 2008)

I agree! The "plus greater of web thickness or 1/2 flange width" is a new requirement in the AASHTO code, so it's likely an old problem that hasn't been updated.

Have you taken the NCEES practice SE I exam yet? The first few problems with the wind loads on the precast wall panels really messed me up. I'm not sure what to think now  Getting ready to do the afternoon portion of that practice exam. Hopefully it's a little better than the morning portion.


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## buening (Oct 20, 2008)

Have you done the morning portion of that exam? I think #125 is incorrect. If you look at the solution and enter the numbers in the Cv equation that they show, you should end up with 2.85. They show the correction factor as 0.85. With a factor of 2.85 &gt; 1.0, then the factor is 1.0 Do you agree, or is my calculator wrong? :brickwall:


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## Jennifer (Oct 20, 2008)

buening said:


> Have you done the morning portion of that exam? I think #125 is incorrect. If you look at the solution and enter the numbers in the Cv equation that they show, you should end up with 2.85. They show the correction factor as 0.85. With a factor of 2.85 &gt; 1.0, then the factor is 1.0 Do you agree, or is my calculator wrong? :brickwall:


That book is at home. I did it last time, so all I did this time was to look over it. I'll check when I get home. I felt like there were some mistakes in the precast questions. In the wall connection problems, they put the diaphram force at the top of the wall instead of at the roof structure. That just doesn't make sense. The diaphram shear force is going to get into the wall at the roof diaphram, not the top of the parapet.


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## Jennifer (Oct 20, 2008)

I looked it over...it looks right to me. I came up with 0.86. The solution in the back checks out for me and I punched it in my calculator again and it seems to come out right again. You are keeping L in feet, right? Although I think that would make it smaller, not bigger.


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## buening (Oct 20, 2008)

Aw shoot, I was adding the three values together instead of multiplying them! :brickwall: Check the errata for the chord forces on those problems you question, the leader was pointing to the wrong line.

Got a few more questions with the same SE I practice exam, maybe you could help/clarify. The solution to 501 shows the L for the column as 13.67 ft. According to ACI, the L should be the clear distance between floors. Wouldn't that be 12ft then, not 13.67?

One other one that I think may be incorrect is the LRFD solution to #525. The section is doubly symmetric, so I think they should use section H1. You would then see if Pr/Pc &gt; 0.2 I get Pr = 32k. The Pc = phi * Fcr * A = 0.9 * 23.7 * 15.6 = 332.75k. The ratio ends up being 0.096 &lt; 0.2, therefore the second equation applies. Pr/(2Pc) + Mr/Mc &lt;1. In their solution, they are finding the stress in the column (P/A) and then use an equation fa/Fa + Mr/Mc This equation lacks the 2 in the denominator of the axial portion. I end up getting 0.814 for the combined ratio compared to their 0.853

I did OK with the afternoon portion, just barely passing. The masonry expansion/contraction questions really threw me for a loop. Such an odd group of questions, and there were like 5 of them!


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## Shaker-PE (Oct 21, 2008)

Jennifer said:


> Ok, Buening, have you worked Problem #55? I think the solution is wrong here, too. I think it should be 65.2, not 60. The AASHTO says to take 12x the slab thickness and add half the girder flange width. Does that sound right to you?



Ok guys, Problem 55 asks for the effective width of the slab for an interior girder. The answer is located in the AASHTO 4.6.2.6.1 under effective flange width.

In the NCEES SE1 practice exam, Problem 129 asks for the effective span length for deck slab design. The answer is located in the AASHTO 4.6.2.1.6 under deck calculation of force effects.

So how do you know. which one to use? I guess if you're given deck thickness then use the first, but if not then use the second. I'm missing something, but does anyone know what the difference is between each of these two length calculations? :blink:


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## Shaker-PE (Oct 21, 2008)

Shaker-PE said:


> Ok guys, Problem 55 asks for the effective width of the slab for an interior girder. The answer is located in the AASHTO 4.6.2.6.1 under effective flange width.
> In the NCEES SE1 practice exam, Problem 129 asks for the effective span length for deck slab design. The answer is located in the AASHTO 4.6.2.1.6 under deck calculation of force effects.
> 
> So how do you know. which one to use? I guess if you're given deck thickness then use the first, but if not then use the second. I'm missing something, but does anyone know what the difference is between each of these two length calculations? :blink:



I'll try to answer my own question here... in problem 129 you're designing the slab, so you go to 4.6.2.1.6 because that's the section for deck design.

In problem 55 you're designing a steel beam, so you go to 4.6.2.6.1 because that's the section for determining how wide your slab is for composite action.

So if the problem asks, what's the effective span length/width... figure out if it's for concrete slab design or for steel beam design, and then proceed to the appropriate AASHTO section. I think that's how I'm going to rationalize the difference.


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## buening (Oct 21, 2008)

That's exactly right. The problem should state "for the deck design, what is the effective slab width?" or " for the girder design, what is the effective slab width?". It took me forever to find the effective slab width section for the deck design. My state DOT has a chart in the bridge manual for deck design, so I never mess with the effective width for the slab design.

Don't forget the Appendix charts for maximum positive and negative bending moments for the deck slab design. It was in the example exam, but not sure if it will be in the real one or not.


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## Jennifer (Oct 21, 2008)

buening said:


> Don't forget the Appendix charts for maximum positive and negative bending moments for the deck slab design. It was in the example exam, but not sure if it will be in the real one or not.


huh? what are you talking about?


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## buening (Oct 21, 2008)

Look at the end of Chapter 4 in AASHTO for the Appendix A. It is a table of moments for the deck design based on the span.


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## Jennifer (Oct 21, 2008)

buening said:


> Look at the end of Chapter 4 in AASHTO for the Appendix A. It is a table of moments for the deck design based on the span.


Oh...ok. The AASHTO stuff is a huge hole in my knowledge. I'm clueless here except what's in SERM and what little knowledge I've picked up doing practice problems.


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## buening (Oct 21, 2008)

Now you know how I feel with the IBC, ASCE 7, ACI masonry, PCI, and many others :beerchug:

The AASHTO is enormous, but at least its all in one code. You might flag a few sections of AASHTO, like the effective flange width sections and the table I mentioned. Tab the load combination page as well. I've been tabbing quite a bit of stuff in the larger manuals.

Let me know about those two problems I question above. I could be wrong though.....like the wood problem


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## Jennifer (Oct 21, 2008)

buening said:


> Now you know how I feel with the IBC, ASCE 7, ACI masonry, PCI, and many others :beerchug:
> The AASHTO is enormous, but at least its all in one code. You might flag a few sections of AASHTO, like the effective flange width sections and the table I mentioned. Tab the load combination page as well. I've been tabbing quite a bit of stuff in the larger manuals.
> 
> Let me know about those two problems I question above. I could be wrong though.....like the wood problem


Yea...I'll check those tonight when I get home. I started to look at it this morning and got off into the errata of the NCEES sample exam. Wow...that's grown since I last checked it...which was before the exam in April. Guess I should keep up with that more.

As for the AASHTO...I tabbed the big general sections for the April exam. I'll add the sections you mentioned. Thanks for your help.

the PCI...I didn't use it very much last time, so I'm not very familiar with it...for the ASCE, tab the sections for the live loads, wind stuff, seismic sections. I would tab the tables in the wind section so you can easily find them and the wind speed map. AISC, i have tabs all over the place...all the tables I use regularly...connections split up by type, beam design charts, column charts...I also tabbed the first page of each of the section property sections.


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## Shaker-PE (Oct 21, 2008)

buening said:


> Aw shoot, I was adding the three values together instead of multiplying them! :brickwall: Check the errata for the chord forces on those problems you question, the leader was pointing to the wrong line.
> Got a few more questions with the same SE I practice exam, maybe you could help/clarify. The solution to 501 shows the L for the column as 13.67 ft. According to ACI, the L should be the clear distance between floors. Wouldn't that be 12ft then, not 13.67?
> 
> One other one that I think may be incorrect is the LRFD solution to #525. The section is doubly symmetric, so I think they should use section H1. You would then see if Pr/Pc &gt; 0.2 I get Pr = 32k. The Pc = phi * Fcr * A = 0.9 * 23.7 * 15.6 = 332.75k. The ratio ends up being 0.096 &lt; 0.2, therefore the second equation applies. Pr/(2Pc) + Mr/Mc &lt;1. In their solution, they are finding the stress in the column (P/A) and then use an equation fa/Fa + Mr/Mc This equation lacks the 2 in the denominator of the axial portion. I end up getting 0.814 for the combined ratio compared to their 0.853
> ...



I noticed the same thing for #501. I think you use the center-to-center spacing in the determination of the Psi factor. You know EI/L over EI/L. But when it comes to finding the effective length (le = k * lu) you use the clear spacing for lu. Check out #65 in the 6 minute solutions. I'm not sure where it would verify this, if I am correct, in the code.

For #525, a W14x53 is singly symmetric. A tube or pipe would be doubly symmetric, right? For the answer, the AISC does say that H2 is permitted to be used instead of H1. And since the ASD question specifically talks about fbx and Fbx, it seems like they're moving you away from H1, which doesn't contain those terms, and into H2 which does contain them. They did change the ASD answer though.

http://www.ncees.org/exams/study_materials...truc_errata.pdf

As for the LRFD option, they make it confusing when switching to moments instead of stresses. However, kl/r is 93.75, so from Table 4-22 Fcr is 22.875 ksi, which makes Pc = 321 k. So I actually get 0.815 but LRFD is not my strength. Personally I do ASD and try to stay away from LRFD. I guess, just hope that the test doesn't present such opposing ideas. But yes, I do think their whole question/answer for LRFD is incorrect. I'd be curious to know how much the answers from H1 and H2 actually differ. What's the right answer? I'm not sure... :blink:


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## Jennifer (Oct 21, 2008)

buening said:


> Aw shoot, I was adding the three values together instead of multiplying them! :brickwall: Check the errata for the chord forces on those problems you question, the leader was pointing to the wrong line.
> Got a few more questions with the same SE I practice exam, maybe you could help/clarify. The solution to 501 shows the L for the column as 13.67 ft. According to ACI, the L should be the clear distance between floors. Wouldn't that be 12ft then, not 13.67?
> 
> One other one that I think may be incorrect is the LRFD solution to #525. The section is doubly symmetric, so I think they should use section H1. You would then see if Pr/Pc &gt; 0.2 I get Pr = 32k. The Pc = phi * Fcr * A = 0.9 * 23.7 * 15.6 = 332.75k. The ratio ends up being 0.096 &lt; 0.2, therefore the second equation applies. Pr/(2Pc) + Mr/Mc &lt;1. In their solution, they are finding the stress in the column (P/A) and then use an equation fa/Fa + Mr/Mc This equation lacks the 2 in the denominator of the axial portion. I end up getting 0.814 for the combined ratio compared to their 0.853
> ...


On 501, I agree it should be 12'...ACI 10.11.3 says it's the clear distance.

I'm still trying to figure out 525.


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## Jennifer (Oct 21, 2008)

on 525, I agree with you...it appears that you should be using eqn. H1-1b. However, with the information they are giving you, you don't have what you need to answer it. Other than that, i don't know what to tell you. It does say that you can use that section in lieu of H1. It would seem to me that M/Mn would be the same as f/F...but I'm not sure it works out that way. I would think the information provided would lead you to the H2 equation...but I'm not sure that's right.


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## Jennifer (Oct 21, 2008)

Shaker, wouldn't an I shape be doubly symetric...you could fold it about both axis, doesn't that make it doubly symetric?


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## buening (Oct 21, 2008)

Doubly symmetric is for all W shapes, HSS shapes, and others. They are a mirror image about each of the X and Y axis. A singly symmetric section would be a C-shape. It is symmetric about one axis, but not about the other axis.

Thanks for the confirmation Angela. I found the exact section of ACI that said it was the clear distance, but wasn't sure if there was a catch somewhere.

Regarding 525, can't you pull the φPn from the AISC tables since you know the KL? The axial force was given in the problem, so looking up the φPn should give you the first part of the H1 equation. It gives the Mu and φMn, so you have the second part of the question.

Thanks for the tips on the building manuals. I have tabs all over the friggin place. I have a feeling I may have too many things tabbed and will never find the sections I need. Oh well

Since I'll be taking the bridge portion of the SE II, I broke up the AASHTO manual into different binders. One binder has Chapters 1-5, another with Ch 6, another with Ch 7, and the last with the remaining chapters. The steel and concrete section are large enough for their own binders, and on the exam the problem will only involve one material.

There are tons of errors in the bridge portion of the SE II practice exam, yet none have been released for the bridge section. I will be submitting my full page of errors, ranging from them pulling the wrong equations to even using allowable stress without phi factors.


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## Jennifer (Oct 22, 2008)

That's what I was thinking on the doubly symetric...tubes, W sections...the WT, Channels would be singly symetric.

On 525, I looked into the P/Pn from the tables, but it didn't give the correct answer. I meant to bring that book to work today to talk with someone over that problem, but I forgot it. I'll still see if I can describe it to him. Let you know what he says.

I thought about splitting my AASHTO up, but decided not to since I need the index to find most of it.


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## Jennifer (Oct 22, 2008)

we looked into the old ASD manual and it only had the equations that are shown in H2. I had the older version of the sample test and all they did was rework the solutions for the new manuals (sometimes rather poorly), we think it's probably a carry over from the older code. I would think if they are writing the exam questions based on the new codes, they would be more likely to give M/Mn values...but I guess we'll see.


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## buening (Oct 22, 2008)

Jennifer said:


> That's what I was thinking on the doubly symetric...tubes, W sections...the WT, Channels would be singly symetric.
> On 525, I looked into the P/Pn from the tables, but it didn't give the correct answer. I meant to bring that book to work today to talk with someone over that problem, but I forgot it. I'll still see if I can describe it to him. Let you know what he says.
> 
> I thought about splitting my AASHTO up, but decided not to since I need the index to find most of it.


Yeah I got a different answer then them using the P/Pn, which was why I wondered if combining ASD axial stresses and LRFD moments ends up throwing things off a bit.

In Illinois we aren't supposed to break up the AASHTO manual, but I did it anyways. I'm bringing the enormous empty binder just in case they give me grief. I copied the index and put it at the end of each binder :beerchug:


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## Jennifer (Oct 22, 2008)

buening said:


> Yeah I got a different answer then them using the P/Pn, which was why I wondered if combining ASD axial stresses and LRFD moments ends up throwing things off a bit.
> In Illinois we aren't supposed to break up the AASHTO manual, but I did it anyways. I'm bringing the enormous empty binder just in case they give me grief. I copied the index and put it at the end of each binder :beerchug:


If you are combining ASD and LRFD, you will get the wrong answer...look at the tables. The LRFD values are significantly higher.


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## Shaker-PE (Oct 22, 2008)

Jennifer said:


> That's what I was thinking on the doubly symetric...tubes, W sections...the WT, Channels would be singly symetric.
> On 525, I looked into the P/Pn from the tables, but it didn't give the correct answer. I meant to bring that book to work today to talk with someone over that problem, but I forgot it. I'll still see if I can describe it to him. Let you know what he says.
> 
> I thought about splitting my AASHTO up, but decided not to since I need the index to find most of it.



Oops, I think you're right about the doubly symmetric thing. I'm always hesitant to even post things because I hate to give out incorrect information. Regardless, good luck on your exams 10940623:


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## Shaker-PE (Oct 22, 2008)

One more question for you guys.... number 538 in the NCEES SE1 book. I understand that the net area is defined in 2.3.3.3.1 as the least of the center to center bar spacing, 6 times nominal wall thickness, or 72 inches. That makes sense, but the area of the steel is shown on page 136 as 0.8 square inches. How do they get that number? It seems to me like it should be a #5 area at 0.31 square inches since we're taking the net width at 4 feet. Do you think I'm missing something or is it a mistake?


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## Jennifer (Oct 22, 2008)

Shaker-PE said:


> One more question for you guys.... number 538 in the NCEES SE1 book. I understand that the net area is defined in 2.3.3.3.1 as the least of the center to center bar spacing, 6 times nominal wall thickness, or 72 inches. That makes sense, but the area of the steel is shown on page 136 as 0.8 square inches. How do they get that number? It seems to me like it should be a #5 area at 0.31 square inches since we're taking the net width at 4 feet. Do you think I'm missing something or is it a mistake?


I'll check into this when I get home...I don't have that here with me.


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## Jennifer (Oct 22, 2008)

Jennifer said:


> I'll check into this when I get home...I don't have that here with me.


honestly I don't think the steel should be included at all in this problem. You can only include the steel in masonry axial design if it is tied. However, I got Pa=12831 for the masonry only and I used .31 for the Ast and got Ast=.31...getting Pa for the steel equal to 1027...total of 13859...not the answer in the book either way. But...if I run their numbers, it doesn't add up in my calculator either way. My way gets me close to the answer. Don't know what to tell you other than I don't agree with it either way

for the steel thing I was talking about see 2.3.2.2.1 and 2.1.6.5. It never says the steel is tied...but I guess if it doesn't...you are supposed to assume it is tied.


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## Shaker-PE (Oct 23, 2008)

Jennifer said:


> honestly I don't think the steel should be included at all in this problem. You can only include the steel in masonry axial design if it is tied. However, I got Pa=12831 for the masonry only and I used .31 for the Ast and got Ast=.31...getting Pa for the steel equal to 1027...total of 13859...not the answer in the book either way. But...if I run their numbers, it doesn't add up in my calculator either way. My way gets me close to the answer. Don't know what to tell you other than I don't agree with it either way
> for the steel thing I was talking about see 2.3.2.2.1 and 2.1.6.5. It never says the steel is tied...but I guess if it doesn't...you are supposed to assume it is tied.



I see what you're saying as far as the code goes for compression steel with the lateral tie requirement. Unfortunately I can't find any other examples that show how to deal with strictly axial loads on reinforced walls using ASD design. I think I'm just going to trust that the example solution is mostly correct, except for the Ast part.


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## Jennifer (Oct 23, 2008)

Shaker-PE said:


> I see what you're saying as far as the code goes for compression steel with the lateral tie requirement. Unfortunately I can't find any other examples that show how to deal with strictly axial loads on reinforced walls using ASD design. I think I'm just going to trust that the example solution is mostly correct, except for the Ast part.


It's just a matter of leaving out the part of the equation that includes the steel. I don't know what to think on that. Yes, though...other than the Ast and the fact that when I punch in their numbers I don't get the same answer, I think they have done the problem correctly...i just have to question whether you should be using the steel.


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