Rigid Pavement Quiz: 5 Questions.... (who can answer all 5?)

[The Wizard]

Ptatohed is the quiz master! You sure are one helpful dude!

 

[John QPE]

I'm getting 14.94 for the wetted perimeter in problem #2

I am using the equation: b+2d[2^2+1]^(1/2) from the National Engineering Handbook

Is there a better equation to use, or am I missing something here? Thanks!

I'm going to go with 8 zero-force members in #5, but 6 seems tempting as well

 

[ptatohed]

I'm getting 14.94 for the wetted perimeter in problem #2

I am using the equation: b+2d[2^2+1]^(1/2) from the National Engineering Handbook

Is there a better equation to use, or am I missing something here? Thanks!

I'm going to go with 8 zero-force members in #5, but 6 seems tempting as well

JQ, for #2, you are calculating the wetted perimeter of the sides as if the slope were 2:1 (H:V), the problem states the sides are at 3:1.

#5 is not D (or C)

Remember the three guidelines:

3 Guidelines for determining zero-force members:

1. [SIZE=12pt]If a joint only has two members and no external load and/or no support, then those two members are zero-force members. [/SIZE]
2. [SIZE=12pt]If a joint only has two members and is loaded, then if the line of action of resultant force from applied loads at the joint collinear with one of the members then the other member is a zero-force member. If the resultant force at the joint is not collinear with either member, then both members are not zero-force members. [/SIZE]
   
3. [SIZE=12pt]If a joint has three members and no external load and/or support, then if two of members are collinear then the non-collinear member is a zero-force member. [/SIZE]
   

 

[John QPE]

Thank you!

For the wetted perimeter I had the problem written correctly in my notes, but entered it wrong on my calculator.

I will print out those guidelines, as these always trip me up. I want to look at that problem again this afternoon.

 

[ptatohed]

You're welcome. John, take a look at this site for zero force members by inspection.

http://www.tekniksipil.org/civil-engineering/engineering-mechanics/zero-force-members-in-trusses-examples/