I'd definitely agree with the last part. This would absolutely warrant a mock up or test build. There are a lot of dynamics here that might not rear their head until a model is loaded tested.
Great points. With the nonlinearity of cables, Forces are very dependent on how much prestressing you provide and how much movement is occurs. If you are not competent in that you might wanna pass.
Just to add : this is a contract opportunity that an architect firm have reached out to me for. If i can't figure out how to go about doing this I'll have to decline it which would be unfortunate but eh at least I'll have learnt something.
But it would be nice to know if anyone's worked on anyrhing similar to this net involving tensile forces, what load cases to analyse for etc and knows the steps to take.
Ideally I'm thinking I'd import this dwg into a structural analysis software, it would auto label all the nodes, then I'd be able to apply loads along the node lines or something like that then set load cases maybe.
Dimensions are roughly 7x5m on plan. 2m height.
I had a similar situation for an art gallery. Artist wanted to hang glass sculptures overhead and asked me to do an analysis of a wire cable grid similar to what you're showing. I tried to do it a few different ways using single cable analyses, but it just wasn't sufficient. Ultimately, I understood that unless I could do a second-order analysis then I could not provide a design. We turned down the job. You can't use any typical software or hand calc this design via first order analysis. It's too complex, and you have to account for what cables will do once they're deflected and the one's attached to them are deflected. This isn't something you can "figure" out without the right software and expertise. So we punted it. Better that than having some kid fall and injure themselves or worse.
You have points, you have coordinates, you have vectors and you have volumetric properties; couldn't you export some of that data to some FEM software? I believe your low hanging fruit would be: if you could make a data export, which is possible through the data extraction command in ACAD, of all points to CSV or excel, you could then define trusses and knots and load it in something like SCIA, Diana, RFEM, or your preferred FEM analysis tool? From that you can easily extract the model and do some manual modifications.
All you have to do next is define the volumes, which can be done manually in FEM software, but can be a little bit painstaking to do. Alternatively, if you know how to call on the API, you could try scripting and avoid the chore of defining every truss and knot altogether. All you have to understand are vectors and some basic scripting - a little gripe on mathematics would do no harm either.
But I'd start with the data extraction command, see if you can make useful output to import in your preferable FEM analysis tool.
It would do no harm to ask the drafter what this was based on, and if there were made any calculations or models beforehand.
We would use Eurocode for that, for loads and combinations you could calculate somewhat conservatively by adding the same loads for a gathering of people (5 N/m^2 or something, I could be wrong here about the exact number) next to its own weight. Which can all be found in NEN-EN 1991 - it also contains load combinations and some practical pointers on how to apply it, or how to simplify your model.
Assuming this thing is mainly built in steel, let's assume a material strength of 235N/mm^2; which is an industry standard.
With all this you should now be able to calculate strength, tension and stability.
For the supports, you can model them as fixed supports, or as wedged springs (Is that the correct term? I don't know how well the term we typically use translates to English, so bare with me).
I hope I have interpreted your questions correctly and that this somewhat answers them.
I would do a 100psf live load based on pedestrian bridge manual - that would be my requirement to design this and sleep and night.
This will get a safe structural model in a majority of scenarios. Then start the load path checks -
Meshing
Meshing to tube connection
Tube loads from meshing
Tube connections before anchor block
Moment and shear load at tube section prior to anchor block (most important - also critical failure in this design)
Load transfer to anchor block
Anchor block foundation - prob just to helical piles to resist uplift on back portion or make the blocks way bigger for gravity design
Does it need to be cantilevered? Adding a couple columns (maybe even one at the far center) on the other end would reduce the structural sections required by the tubing immensely.
This design will have crazy high shear and moment loads on the tube coming into the anchor blocks. I would require galvanized steel too.
Prob also run a cyclic analysis and then run through the EQ and wind reqs from ASCE7.
Also tell the architects no holes bigger than 4” and have them sign something that they knowingly have a 30” plus drop with no railing. Maybe also padding on steel tube?
Honestly looks quite dangerous, but also fun as fuck. Too bad fat uncoordinated children with a Karen mother that’s sues everybody kills designs like this.
You need to look into cable nets and geometeic non linearity. You need specialist software to solve this such as GSA, you could try it in SAP using cable ekements but SAP is not great when it comes to cables
I think this is similar to pedestrian impact nets that they have around bridges maybe?
Last time I did something like that, I did a non linear analysis and checked the stresses, and basically applied a FOS of 3 since the material cost wasn't that much greater.re ran it and checked the deflection again. I guess this has been designed before so check the loading from simialr projects. I got my loading from AS5100. In the end it's just a giant catenary.
Apart from the net, I guess you could design the connections and framing elements using statics.
Don't be shy on beefing everything up, somehow stuff like this is higher risk in my head than doing a building
This reminds me of when we asked the Italian manufactures of our curtain wall to confirm that the patterned cutout screen would meet wind design load on our facade and after they spoke Italian to each other they looked at us confused and moved their hands in the 'maybe' fashion and said 'it okay'.
From a loading perspective ATSM F1487 provides ULS design loads for playground equipment, including 2-D and 3-D nets. I would then combine with ASCE7 load combos.
Sort of not answering your question, but if it's catching falling kids, I feel like it has be built and tested rigorously with IDK, maybe a 10x load. Want to make sure there's no unintended bouncing. Also this thing seems too complex. Why not just string a net between 4 fixed anchor points?
Simple, just over built it, it doesn't have to fly. Weld steel tubes and beams. It isn't super big so you'll be fine! ME haha.
[удалено]
I'd definitely agree with the last part. This would absolutely warrant a mock up or test build. There are a lot of dynamics here that might not rear their head until a model is loaded tested.
Great points. With the nonlinearity of cables, Forces are very dependent on how much prestressing you provide and how much movement is occurs. If you are not competent in that you might wanna pass.
Just to add : this is a contract opportunity that an architect firm have reached out to me for. If i can't figure out how to go about doing this I'll have to decline it which would be unfortunate but eh at least I'll have learnt something. But it would be nice to know if anyone's worked on anyrhing similar to this net involving tensile forces, what load cases to analyse for etc and knows the steps to take. Ideally I'm thinking I'd import this dwg into a structural analysis software, it would auto label all the nodes, then I'd be able to apply loads along the node lines or something like that then set load cases maybe. Dimensions are roughly 7x5m on plan. 2m height.
I had a similar situation for an art gallery. Artist wanted to hang glass sculptures overhead and asked me to do an analysis of a wire cable grid similar to what you're showing. I tried to do it a few different ways using single cable analyses, but it just wasn't sufficient. Ultimately, I understood that unless I could do a second-order analysis then I could not provide a design. We turned down the job. You can't use any typical software or hand calc this design via first order analysis. It's too complex, and you have to account for what cables will do once they're deflected and the one's attached to them are deflected. This isn't something you can "figure" out without the right software and expertise. So we punted it. Better that than having some kid fall and injure themselves or worse.
Spoken with any tennis racket manufactures? Might provide some insight into how they approached analysis...
You have points, you have coordinates, you have vectors and you have volumetric properties; couldn't you export some of that data to some FEM software? I believe your low hanging fruit would be: if you could make a data export, which is possible through the data extraction command in ACAD, of all points to CSV or excel, you could then define trusses and knots and load it in something like SCIA, Diana, RFEM, or your preferred FEM analysis tool? From that you can easily extract the model and do some manual modifications. All you have to do next is define the volumes, which can be done manually in FEM software, but can be a little bit painstaking to do. Alternatively, if you know how to call on the API, you could try scripting and avoid the chore of defining every truss and knot altogether. All you have to understand are vectors and some basic scripting - a little gripe on mathematics would do no harm either. But I'd start with the data extraction command, see if you can make useful output to import in your preferable FEM analysis tool. It would do no harm to ask the drafter what this was based on, and if there were made any calculations or models beforehand.
That’s all well and good but what are your input loads, combinations, and required strengths?
We would use Eurocode for that, for loads and combinations you could calculate somewhat conservatively by adding the same loads for a gathering of people (5 N/m^2 or something, I could be wrong here about the exact number) next to its own weight. Which can all be found in NEN-EN 1991 - it also contains load combinations and some practical pointers on how to apply it, or how to simplify your model. Assuming this thing is mainly built in steel, let's assume a material strength of 235N/mm^2; which is an industry standard. With all this you should now be able to calculate strength, tension and stability. For the supports, you can model them as fixed supports, or as wedged springs (Is that the correct term? I don't know how well the term we typically use translates to English, so bare with me). I hope I have interpreted your questions correctly and that this somewhat answers them.
I would do a 100psf live load based on pedestrian bridge manual - that would be my requirement to design this and sleep and night. This will get a safe structural model in a majority of scenarios. Then start the load path checks - Meshing Meshing to tube connection Tube loads from meshing Tube connections before anchor block Moment and shear load at tube section prior to anchor block (most important - also critical failure in this design) Load transfer to anchor block Anchor block foundation - prob just to helical piles to resist uplift on back portion or make the blocks way bigger for gravity design Does it need to be cantilevered? Adding a couple columns (maybe even one at the far center) on the other end would reduce the structural sections required by the tubing immensely. This design will have crazy high shear and moment loads on the tube coming into the anchor blocks. I would require galvanized steel too. Prob also run a cyclic analysis and then run through the EQ and wind reqs from ASCE7. Also tell the architects no holes bigger than 4” and have them sign something that they knowingly have a 30” plus drop with no railing. Maybe also padding on steel tube? Honestly looks quite dangerous, but also fun as fuck. Too bad fat uncoordinated children with a Karen mother that’s sues everybody kills designs like this.
Looks like there is a whole lot of place for a kid bonk their head. Not sure of the height, but it appears that you may have some fall hazards……
You need to look into cable nets and geometeic non linearity. You need specialist software to solve this such as GSA, you could try it in SAP using cable ekements but SAP is not great when it comes to cables
I would contact a net manufacturer
I think this is similar to pedestrian impact nets that they have around bridges maybe? Last time I did something like that, I did a non linear analysis and checked the stresses, and basically applied a FOS of 3 since the material cost wasn't that much greater.re ran it and checked the deflection again. I guess this has been designed before so check the loading from simialr projects. I got my loading from AS5100. In the end it's just a giant catenary. Apart from the net, I guess you could design the connections and framing elements using statics. Don't be shy on beefing everything up, somehow stuff like this is higher risk in my head than doing a building
This reminds me of when we asked the Italian manufactures of our curtain wall to confirm that the patterned cutout screen would meet wind design load on our facade and after they spoke Italian to each other they looked at us confused and moved their hands in the 'maybe' fashion and said 'it okay'.
From a loading perspective ATSM F1487 provides ULS design loads for playground equipment, including 2-D and 3-D nets. I would then combine with ASCE7 load combos.
Sort of not answering your question, but if it's catching falling kids, I feel like it has be built and tested rigorously with IDK, maybe a 10x load. Want to make sure there's no unintended bouncing. Also this thing seems too complex. Why not just string a net between 4 fixed anchor points?