Assume the following: A small bridge (5.5m) is to be built, slate stone on aluminum decking is laid on two beams (VKR) which are assumed to be freely supported on supports that can handle everything.
Superstructure (slate etc.) weighs 1.1 ton = 11kN divided by 5.5m gives q= 11/5= 2kN/m
Field moment qL^2/8 gives (2*5.5^2)/8 = 7.56kN/m
Also assume a point load when a person, 100kg 1kN, should be able to walk across the bridge:
PL/4= 1*5.5/4= 1.375kN/m
Total thus 8.93 kN/m (???), divided by two beams is about 4.5kN/m per beam. A VKR 40x40x3.2 has Wx= 5.11 and should then work, right?
Is this calculation correct? You should possibly take into account snow load 1.5kN/m2, but the question is, does this calculation/methodology hold? Anyone can? The bridge will not be built.
Superstructure (slate etc.) weighs 1.1 ton = 11kN divided by 5.5m gives q= 11/5= 2kN/m
Field moment qL^2/8 gives (2*5.5^2)/8 = 7.56kN/m
Also assume a point load when a person, 100kg 1kN, should be able to walk across the bridge:
PL/4= 1*5.5/4= 1.375kN/m
Total thus 8.93 kN/m (???), divided by two beams is about 4.5kN/m per beam. A VKR 40x40x3.2 has Wx= 5.11 and should then work, right?
Is this calculation correct? You should possibly take into account snow load 1.5kN/m2, but the question is, does this calculation/methodology hold? Anyone can? The bridge will not be built.
A small initial remark while I think further: Moments are stated in kNm kN/m is a line loadNiclas W said:Assume the following: A small bridge (5.5m) will be built, slate stone on an aluminum floor placed on two beams (VKR) assumed to be freely supported on supports that can handle everything.
Superstructure (slate, etc.) weighs 1.1 tons = 11kN divided by 5.5m gives q= 11/5= 2kN/m
Field moment qL2/8 gives (2*5.5^2)/8 = 7.56kN/m Assume also a point load when a person, 100kg 1kN, should be able to walk over the bridge: PL/4= 1*5.5/4= 1.375kN/m In total, therefore, 8.93 kN/m (???), divided into two beams is about 4.5kN/m per beam. A VKR 40x40x3.2 has Wx= 5.11 and should then be fine, right?
Is this calculation correct? We should possibly include snow load 1.5kN/m2, but the question is, does this calculation/methodology hold? Can anyone confirm? The bridge will not be built.
Thinking a bit about your load case:
You cannot assume that such a bridge with that length will only be loaded by a single person.
You need to significantly increase the useful load. At least to 2 kN/m2, as is used for floor structures. I can imagine that you should probably increase it even more, as people might very well stand closely together on a bridge to check out the fish or the flowing water.
Your calculation with your load case and two VKR 40x40x3.2 otherwise results in a reasonable stress on the steel.
You cannot assume that such a bridge with that length will only be loaded by a single person.
You need to significantly increase the useful load. At least to 2 kN/m2, as is used for floor structures. I can imagine that you should probably increase it even more, as people might very well stand closely together on a bridge to check out the fish or the flowing water.
Your calculation with your load case and two VKR 40x40x3.2 otherwise results in a reasonable stress on the steel.
Moment= kNm, true
After some research, the required Wx for the beam in question is calculated by dividing the maximum moment by the steel's yield strength. Then for me, it's a jumble of different multiples, etc., when looking into steel tables....
After some research, the required Wx for the beam in question is calculated by dividing the maximum moment by the steel's yield strength. Then for me, it's a jumble of different multiples, etc., when looking into steel tables....
Not yield strength???Niclas W said:
That value is too high.
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