Bridge Building 2016

[nxtscholar]

So someone correct me if I'm wrong (I'm a biomathematics major, although one with a strong interest in engineering), but I had a sudden pop into my mind that I'm rather curious about.

Does this year's rules with regards to the test support actually affect division B more and thus pose a bigger challenge to them than division C? Like, by nature of the rules, division C bridges are longer than division B bridges because of a longer mandated span. Consequently, the test support creates a larger angle of inclination for division B bridges than division C bridges. I'm going along the lines of simple geometry. For division C, it's a "rise" of 5 cm to a "run" of 45 cm. For division B, it's about a rise of 5 cm to run of 35 cm.

Thus, doesn't this create a larger change in the direction of forces and stress for division B than division C compared to last year? In other words, don't division B teams have more to change in their designs than division C with regards to changing truss designs, thickness of members, etc.?

I emphasize, however, that regardless of division, the test support doesn't seem to be changing the problem that much. But the question I ask is does division B technically have more to deal with than division C in terms of change?

I don't have an answer at this hour but the different spans brings up another question: does the "tilt" have more of an effect for a large angle change involving a short span or a smaller angle involving a longer span? Does span or angle affect the challenge more? I would guess the span's added challenge dramatically increases with greater spans, with greater angles adding more challenge but with less of a magnitude. Just a guess coming from a sleepy person though.

Oh that is true...it's possible a change in angle impacts longer span bridges faster than shorter span bridges. But I don't take statics, so...

[bernard]

So someone correct me if I'm wrong (I'm a biomathematics major, although one with a strong interest in engineering), but I had a sudden pop into my mind that I'm rather curious about.

Does this year's rules with regards to the test support actually affect division B more and thus pose a bigger challenge to them than division C? Like, by nature of the rules, division C bridges are longer than division B bridges because of a longer mandated span. Consequently, the test support creates a larger angle of inclination for division B bridges than division C bridges. I'm going along the lines of simple geometry. For division C, it's a "rise" of 5 cm to a "run" of 45 cm. For division B, it's about a rise of 5 cm to run of 35 cm.

Thus, doesn't this create a larger change in the direction of forces and stress for division B than division C compared to last year? In other words, don't division B teams have more to change in their designs than division C with regards to changing truss designs, thickness of members, etc.?

I emphasize, however, that regardless of division, the test support doesn't seem to be changing the problem that much. But the question I ask is does division B technically have more to deal with than division C in terms of change?

I don't have an answer at this hour but the different spans brings up another question: does the "tilt" have more of an effect for a large angle change involving a short span or a smaller angle involving a longer span? Does span or angle affect the challenge more? I would guess the span's added challenge dramatically increases with greater spans, with greater angles adding more challenge but with less of a magnitude. Just a guess coming from a sleepy person though.

Oh that is true...it's possible a change in angle impacts longer span bridges faster than shorter span bridges. But I don't take statics, so... :P

With the chair setup at the NJIT regional, I think you'd also need some experience with dynamics...

[dholdgreve]

So someone correct me if I'm wrong (I'm a biomathematics major, although one with a strong interest in engineering), but I had a sudden pop into my mind that I'm rather curious about.

Does this year's rules with regards to the test support actually affect division B more and thus pose a bigger challenge to them than division C? Like, by nature of the rules, division C bridges are longer than division B bridges because of a longer mandated span. Consequently, the test support creates a larger angle of inclination for division B bridges than division C bridges. I'm going along the lines of simple geometry. For division C, it's a "rise" of 5 cm to a "run" of 45 cm. For division B, it's about a rise of 5 cm to run of 35 cm.

Thus, doesn't this create a larger change in the direction of forces and stress for division B than division C compared to last year? In other words, don't division B teams have more to change in their designs than division C with regards to changing truss designs, thickness of members, etc.?

I emphasize, however, that regardless of division, the test support doesn't seem to be changing the problem that much. But the question I ask is does division B technically have more to deal with than division C in terms of change?

I see where you are coming from, and yes, as the span decreases, the angle of the bridge increases... depending on how you design your bridge... In theory, you could design an elevated bridge, then chop off the elevated legs on one side... In that case, there is no angle due to the elevation change.

[Phys1cs]

I see where you are coming from, and yes, as the span decreases, the angle of the bridge increases... depending on how you design your bridge... In theory, you could design an elevated bridge, then chop off the elevated legs on one side... In that case, there is no angle due to the elevation change.

The issue with just building an elevated bridge and chopping off one sides legs is the maximum 2cm clearance on the not inclined side. You couldn't build 5cm high legs, since that would be higher than the allowed height of the lower side. You could possibly build 1.5-2cm high legs, but I don't think that would be the most efficient solution to the problem. Though it does make the angle a little smaller

[dholdgreve]

So someone correct me if I'm wrong (I'm a biomathematics major, although one with a strong interest in engineering), but I had a sudden pop into my mind that I'm rather curious about.

Does this year's rules with regards to the test support actually affect division B more and thus pose a bigger challenge to them than division C? Like, by nature of the rules, division C bridges are longer than division B bridges because of a longer mandated span. Consequently, the test support creates a larger angle of inclination for division B bridges than division C bridges. I'm going along the lines of simple geometry. For division C, it's a "rise" of 5 cm to a "run" of 45 cm. For division B, it's about a rise of 5 cm to run of 35 cm.

Thus, doesn't this create a larger change in the direction of forces and stress for division B than division C compared to last year? In other words, don't division B teams have more to change in their designs than division C with regards to changing truss designs, thickness of members, etc.?

I emphasize, however, that regardless of division, the test support doesn't seem to be changing the problem that much. But the question I ask is does division B technically have more to deal with than division C in terms of change?

I see where you are coming from, and yes, as the span decreases, the angle of the bridge increases... depending on how you design your bridge... In theory, you could design an elevated bridge, then chop off the elevated legs on one side... In that case, there is no angle due to the elevation change.

You can if you slope the leg inward, so at the point where the opening starts it is equal to or less than 2 CM

[embokim]

Does anybody have anything to say about a trapezoid shaped bridge with no joints around the actual contact point of the loading block and the bridge?
Last minute ideas, thank you.

[bernard]

Does anybody have anything to say about a trapezoid shaped bridge with no joints around the actual contact point of the loading block and the bridge?
Last minute ideas, thank you. :mrgreen:

Try to include a drawing. I'm not sure exactly what you mean and am thinking of many designs that match what you described.

[Mr_Pep_Band]

Hi all, I am new to this forum but competed in Science Olympiad in high school, and have run the Bridge Bruilding/Boomilever/Towers event the last 5 years at North Dakota State competition whilst in college at NDSU. Every year I have facilitated State competition, I try to build 2-3 bridges for fun and to better understand the event and what it takes to win. This year they threw a curve ball at us with the unsymmetrical loading abutments.

Am I correct in how this is laid out in CAD for the C Division with the 5 cm tall abutment on one side and then the max 2 cm height on the other side?

[JonB]

Hi all, I am new to this forum but competed in Science Olympiad in high school, and have run the Bridge Bruilding/Boomilever/Towers event the last 5 years at North Dakota State competition whilst in college at NDSU. Every year I have facilitated State competition, I try to build 2-3 bridges for fun and to better understand the event and what it takes to win. This year they threw a curve ball at us with the unsymmetrical loading abutments.

Am I correct in how this is laid out in CAD for the C Division with the 5 cm tall abutment on one side and then the max 2 cm height on the other side?

C Layout.PNG

Looks correct to me!

[dholdgreve]

Hi all, I am new to this forum but competed in Science Olympiad in high school, and have run the Bridge Bruilding/Boomilever/Towers event the last 5 years at North Dakota State competition whilst in college at NDSU. Every year I have facilitated State competition, I try to build 2-3 bridges for fun and to better understand the event and what it takes to win. This year they threw a curve ball at us with the unsymmetrical loading abutments.

Am I correct in how this is laid out in CAD for the C Division with the 5 cm tall abutment on one side and then the max 2 cm height on the other side?

C Layout.PNG

yes, your dwg is correct... One thing we were unprepared for at the competition we ran, is that a few teams, in order to get below the 2 cm rule on the one side, had to shift the 5 CM block further off the line in order to properly bear the feet of the bridge on the elevated side... After a careful review of the rules, they do not say that the elevation block must "toe the line." It can be located anywhere in the bearing zone behind the line, so we allowed them to position it wherever they wanted, as long as it was behind the line.