Bridge question?

aom

aom

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Ok, as usual I know a design is required but in the mean time I went to price a proposed new bridge yesterday which is a 20m span. They are craning over a steel support before the decking works can begin which will be the usual steel decking then poured concrete with abutments and hand rail. The guy I was pricing it for had sat and studied the job for a long time and had finally come up with some weird and wonderful solution to scaffold it which would just be too complicated to explain.

My solution, would be far simpler, just build a beam job on the deck then crane it in to position where we could build 2 towers from a solid concrete base, simple really but we are restricted to 5 ton on the crane at that distance. The towers could be drilled in using thunder bolts to their own foundation and there is the steel frame to get a tie into although it may be difficult to get them out as the steel frame will be about 1m away from the scaffold. It's mainly just for fall protection so a light duty is all that is required.

Do you reckon this is as simple as I am thinking or am I missing something?
 
just a guess and a stab in the dark as i cant properly visualise the job but,
why not build the beam section and then build the access up from it and onto the bridge deck?
would that be possible,as long as you pick up and pickback from the end of the beams
 
The bridge deck will have to be kept clear as the steel going over is quite narrow and they intend using that corrugated steel decking to support the concrete to form the finished level. I will be spanning either side of the bridge so can link the 2 together above head height using more beams but wasn't sure exactly how effective that would be.

I think it's a straight forward enough wee job to be honest, the contractors over the top design put me off my stride a bit in case I was missing something but all I see really is a beam job thrown over either side of a bridge, the contractor is doing all the crane work and forming me a concrete foundation so all should be good. As long as I can get a few ties into the steel frame I think I'm laughing.
 
haha, not really. Just waiting for the wife and then getting dragged round Braehead where I will be bored stiff.

Do you reckon my wee bridge job is simple enough then?
 
aom said:
haha, not really. Just waiting for the wife and then getting dragged round Braehead where I will be bored stiff.

Do you reckon my wee bridge job is simple enough then?
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Ask yer ipad:eek:
 
haha, don't think it would work up here BF, even these phone systems you talk too have started hanging up on me.:eek:
 
If there's a crane going begging make sure you use it!!!
 
I bet when you get your design back on a twenty metre span they'll have put six or seven sets of beams and about three hundred knee bracing and the fecking crane wont be able to lift the damn thing :D
 
aom said:
Ok, as usual I know a design is required but in the mean time I went to price a proposed new bridge yesterday which is a 20m span. They are craning over a steel support before the decking works can begin which will be the usual steel decking then poured concrete with abutments and hand rail. The guy I was pricing it for had sat and studied the job for a long time and had finally come up with some weird and wonderful solution to scaffold it which would just be too complicated to explain.

My solution, would be far simpler, just build a beam job on the deck then crane it in to position where we could build 2 towers from a solid concrete base, simple really but we are restricted to 5 ton on the crane at that distance. The towers could be drilled in using thunder bolts to their own foundation and there is the steel frame to get a tie into although it may be difficult to get them out as the steel frame will be about 1m away from the scaffold. It's mainly just for fall protection so a light duty is all that is required.

Do you reckon this is as simple as I am thinking or am I missing something?
Click to expand...

Your solution of building it on the deck and craning it in is best ,we do stuff like that quite often, only we are not restricted to 5 ton.
If it is too heavy leave the boards off and just fit one handrail ,they can be fitted when the beams fixed into the towers
 
scaffman1 said:
I bet when you get your design back on a twenty metre span they'll have put six or seven sets of beams and about three hundred knee bracing and the fecking crane wont be able to lift the damn thing :D
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That is my fear, we could do as Nick suggests, leave the wood out and even some of the knee brace and do that progressively but ideally they are looking for a solution that takes working at height out the equation. The last time I priced a similar job they eventually brought in a crane jib and flung that across the span, all we got to do was fit hand rails to it.:(

Nick,

I think the main problem restricting the size of the crane is it's location, it's in the middle of nowhere halfway up a mountain.
 
just give us a bell marra ill pull ya out of it again ;) crnt see the problem with bridging it am i right in thinking the bridge will already be built and its just for hand rails? if os you not sugetes an underbridge motor and punch up of it to for you hand rails ?
 
aom said:
Ok, as usual I know a design is required but in the mean time I went to price a proposed new bridge yesterday which is a 20m span. They are craning over a steel support before the decking works can begin which will be the usual steel decking then poured concrete with abutments and hand rail. The guy I was pricing it for had sat and studied the job for a long time and had finally come up with some weird and wonderful solution to scaffold it which would just be too complicated to explain.

My solution, would be far simpler, just build a beam job on the deck then crane it in to position where we could build 2 towers from a solid concrete base, simple really but we are restricted to 5 ton on the crane at that distance. The towers could be drilled in using thunder bolts to their own foundation and there is the steel frame to get a tie into although it may be difficult to get them out as the steel frame will be about 1m away from the scaffold. It's mainly just for fall protection so a light duty is all that is required.

Do you reckon this is as simple as I am thinking or am I missing something?
Click to expand...

Morning AOM
not sure I have a total understanding of what you are trying to achieve, however, take care if this is intended to be a man catching platform as it may fall outside the “light duty” category which would typically be 0.75kN/mSq
TG20 section 21 will give you a better idea of the loads to be allowed.

Even this would be a hefty scaffold, example
0.75kN/mSq imposed
0.25kN/mSq Deck
0.5kN/mSqs Self WT (minimum)
Total 1.5kN/mSq
Don’t know how wide your structure needs to be but lets work on a 1.0m wide platform area
20m x 1.0m x1.5kN = 30kN
BM = WL/8 = 75kNm which would need 3 or 4 rows of unit beam minimum for each 1.0m width of platform.

If this is just a fall protection platform would they not be better off running nets instead?
regards
Alan
 
Thanks for your input Alan, I maybe never explained it all that well as usual but there will be nets erected as well, just not by me. I can't remember the exact dimensions but the bridge will be formed initially about 3m wide using a steel frame, then they put down that corrugated steel decking that acts as a shutter for the concrete to be poured which is cantilevered out from the steel so the bridge will now be 4m odd wide, so the scaffold will be nearly 1m away from the initial steel base until the decking is installed.

I am not sure if that makes any more sense or not but the scaffold while being mainly for protection will also need to act as a light duty working platform for men only. I also think you will be near enough with at least 3 or 4 rows of beams as we did a similar set up for a pedestrian walkway a few years back and that was 4 wide but as you know the required loads for public access are very different than that required here.

To be honest, I would be more than happy to build this in situ as it's pretty basic but rightly so the clients are demanding the main contractor finds a solution to minimise work at height. I know, strange right?

The maximum lift will be 5 ton, due to other site restrictions, so the key to success will be finding a design scheme that will hopefully allow us to build the complete job under that limit. I suppose the Apollo X beams would help?

---------- Post added at 02:17 PM ---------- Previous post was at 02:13 PM ----------
marra watson said:
just give us a bell marra ill pull ya out of it again ;) crnt see the problem with bridging it am i right in thinking the bridge will already be built and its just for hand rails? if os you not sugetes an underbridge motor and punch up of it to for you hand rails ?
Click to expand...

My first go at a solution marra was to undersling beams across it's width as there is a chunk of steel going down first but as the concrete goes down to almost 1m either side it would almost be impossible to get anything back after.

I may not be explaining the job very well, I may try and post a copy of parts of the drawing to give you a look, I still can't do that painting malarky thingwy that you do. :embarrest:
 
aom said:
Thanks for your input Alan, I maybe never explained it all that well as usual but there will be nets erected as well, just not by me. I can't remember the exact dimensions but the bridge will be formed initially about 3m wide using a steel frame, then they put down that corrugated steel decking that acts as a shutter for the concrete to be poured which is cantilevered out from the steel so the bridge will now be 4m odd wide, so the scaffold will be nearly 1m away from the initial steel base until the decking is installed.

I am not sure if that makes any more sense or not but the scaffold while being mainly for protection will also need to act as a light duty working platform for men only. I also think you will be near enough with at least 3 or 4 rows of beams as we did a similar set up for a pedestrian walkway a few years back and that was 4 wide but as you know the required loads for public access are very different than that required here.

To be honest, I would be more than happy to build this in situ as it's pretty basic but rightly so the clients are demanding the main contractor finds a solution to minimise work at height. I know, strange right?

The maximum lift will be 5 ton, due to other site restrictions, so the key to success will be finding a design scheme that will hopefully allow us to build the complete job under that limit. I suppose the Apollo X beams would help?

---------- Post added at 02:17 PM ---------- Previous post was at 02:13 PM ----------



My first go at a solution marra was to undersling beams across it's width as there is a chunk of steel going down first but as the concrete goes down to almost 1m either side it would almost be impossible to get anything back after.

I may not be explaining the job very well, I may try and post a copy of parts of the drawing to give you a look, I still can't do that painting malarky thingwy that you do. :embarrest:
Click to expand...



phil has mentioned importing some very strong and light may i add carbon nutral biodegradale maretials form the far east think it may be called baboocup. are you thinking tube and fit or cup lock cup lock would enable you to have less gear in it wouldnt it thust redusing the weight (not sure of cuplock bay sizes but i know layher do a 10ft bay) and will it bee netted under the corragated bottom or would thta nee to be beamed under and matted out
 
marra watson said:
phil has mentioned importing some very strong and light may i add carbon nutral biodegradale maretials form the far east think it may be called baboocup. are you thinking tube and fit or cup lock cup lock would enable you to have less gear in it wouldnt it thust redusing the weight (not sure of cuplock bay sizes but i know layher do a 10ft bay) and will it bee netted under the corragated bottom or would thta nee to be beamed under and matted out
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That will be netted, not entirely sure how these boys are going to net it though without working at height but to be honest that's their problem, hopefully.

The contractor is desperate to do this job well as the usual carrot of a lot more of these types of bridges are being planned so he is promising me all sorts of help including a solid concrete base to build from at really any height I suggest so the beams will be the working lift, no need for any further steel.
 
marra watson said:
phil has mentioned importing some very strong and light may i add carbon nutral biodegradale maretials form the far east think it may be called baboocup. are you thinking tube and fit or cup lock cup lock would enable you to have less gear in it wouldnt it thust redusing the weight (not sure of cuplock bay sizes but i know layher do a 10ft bay) and will it bee netted under the corragated bottom or would thta nee to be beamed under and matted out
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Excuse me but if anyone is going to be importing anything from the Far East it will be me. Except obviously Cape if they get work visas for their Filipinos.
 
If the problem is retrieval of the beams after completion,could you not run a job straight down the centre of the bridge with the beams overhead and just hang a lift either side?maybe the concrete pour would scupper this route though,we need a picture or plan aom:cool:
 
Havespannerwilltravel said:
Excuse me but if anyone is going to be importing anything from the Far East it will be me. Except obviously Cape if they get work visas for their Filipinos.
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i totally retract that statment as i have know evidence of it any were other than i quote '' a susgestion that phil may be using bamboo in the near future'' all be it it may be use for alpha to chaw on it as wukshy lashes it together i have know idea but my apoligies please dont send me the letter
 
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