Rumour has it they will be included in TG20:13. The question that springs to mind are which ones!
Actually dug out the original SGB data sheet for them today. It really is very vague in my view...as Alan said it states ok to omit ledger braces upto 30m tall unsheeted. Problem is it makes reference to BS 5973 and specifies that 1 tie per 40sq.m is required.
Says nothing about lift heights...don't recall did 5973 have a maximum of 2.0m??
Anyway heres a scenario. Ties at 10m vertical centres x 4m horizontal centres! 40 sq.m per tie...do you think this would be acceptable?? Ok I know 5973 gave a maximum distance between ties of I think 8.5m and erecting 10m before tying is difficult (but don't say that doesn't happen!), but it does demonstrate how vague and open to interpretation the data is.
The lack of technical guidance and vagueness of the data that did exist maybe demonstrates why us designers are reluctant to omit the ledger braces.
If anyone is interested in seeing the data sheet give me a shout.
Those who do use them and leave the ledger braces out...ask yourself this...if you do have an incident where are you going to go, what will you reference when the judge asks why you omitted the braces because as of now it does NOT exist.
Actually dug out the original SGB data sheet for them today. It really is very vague in my view...as Alan said it states ok to omit ledger braces upto 30m tall unsheeted. Problem is it makes reference to BS 5973 and specifies that 1 tie per 40sq.m is required.
Says nothing about lift heights...don't recall did 5973 have a maximum of 2.0m??
Anyway heres a scenario. Ties at 10m vertical centres x 4m horizontal centres! 40 sq.m per tie...do you think this would be acceptable?? Ok I know 5973 gave a maximum distance between ties of I think 8.5m and erecting 10m before tying is difficult (but don't say that doesn't happen!), but it does demonstrate how vague and open to interpretation the data is.
The lack of technical guidance and vagueness of the data that did exist maybe demonstrates why us designers are reluctant to omit the ledger braces.
If anyone is interested in seeing the data sheet give me a shout.
Those who do use them and leave the ledger braces out...ask yourself this...if you do have an incident where are you going to go, what will you reference when the judge asks why you omitted the braces because as of now it does NOT exist.