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anchorengineer
19th October 2011, 08:11 PM
Hello,
I'm a structural engineer in the US and I've been in design for 15 years but I'm relatively new to scaffold design. I am typically designing with fixed frames that are about 6ft tall and are spaced at 8ft on center. I have allowable load capacities for the frames from the scaffold manufacturers. The capacities are given per number of frames unsupported vertically. What I'm not 100% sure on is the horizontal spacing of the ties. I would assume that each frame in each column on the way up would need a tie but I am constantly seeing spacings of 24' from other engineers. I'm concerned about leaving a tower of frames not tied to the structure. Most of my structures are over 150 ft tall. I've been designing my ties to be staggered so this does not happen. I'm constantly seeing other designs that do not address this. Does anyone have technical data to justify a spacing that large? Is there something I'm missing?
Thanks!
Brian

philliosmaximus
19th October 2011, 08:15 PM
Welcome Brian there are a few scaffold designers here mate who iam sure will be able to help you out :)

scaffy
20th October 2011, 05:35 AM
Welcome

bigfish
20th October 2011, 05:58 AM
Generally in this country(uk)the tie pattern is every 4m across and 4m up,in either a grid or diamond pattern,but i'm sure some of the designer's on here can be more specific,not so sure on the conformity of the us though:bigsmile:
Howdy:cool:

HatterScaff
20th October 2011, 07:50 AM
Hello,
I'm a structural engineer in the US and I've been in design for 15 years but I'm relatively new to scaffold design. I am typically designing with fixed frames that are about 6ft tall and are spaced at 8ft on center. I have allowable load capacities for the frames from the scaffold manufacturers. The capacities are given per number of frames unsupported vertically. What I'm not 100% sure on is the horizontal spacing of the ties. I would assume that each frame in each column on the way up would need a tie but I am constantly seeing spacings of 24' from other engineers. I'm concerned about leaving a tower of frames not tied to the structure. Most of my structures are over 150 ft tall. I've been designing my ties to be staggered so this does not happen. I'm constantly seeing other designs that do not address this. Does anyone have technical data to justify a spacing that large? Is there something I'm missing?
Thanks!
Brian

Welcome Brian
From the sound of it, you seem to be constructing with some type of system scaffold, the manufactures should supply some data on tie patterns
I know a few designers here that would say systems are to be tied at every frame, every lift, let us know if it is a system or traditional type tube & fitting
but if it is tube & fitting, it should usally be tied at every braced frame, every other lift 4m x 4m as others have said, cladding will also have an impact and how many boarded lifts, and at over 150' the leg load will also need looking at, volume 2 of TG20 may be usefull to you

Georgina Molloy
20th October 2011, 08:04 AM
Hi Brian,

If you are using a system scaffold (which it sounds like) the manufacturer should supply you with a required tie pattern. Be careful to tell them if there is sheeting or netting on the scaffold.
You are right to say that each standard needs to have a tie at some point up the scaffold (usually 4m vertically with the tie pattern staggered).

---------- Post added at 09:04 AM ---------- Previous post was at 09:02 AM ----------

Also,

The tie pattern dictates the allowable axial load on the standard so that may dictate how close your ties should be.

---------- Post added at 09:04 AM ---------- Previous post was at 09:04 AM ----------

Also,

The tie pattern dictates the allowable axial load on the standard so that may dictate how close your ties should be.

frederik
20th October 2011, 08:12 AM
Welcome to the forum anchorman, Im not a designer/engineer but just thought i'de throw my two pence worth in to the pot. Most of us on here are tube and fitting/clamp men. The tie system varies with height wind and use. Strength of structure your tieing to.We also attach monaflex to the outside of scaffolds,its like a huge sale,dust protection etc. hence wind speeds are factored in. The older structures were built with lime and morter,so may not stand up to pullout tests so more ties may be required. I would think 24ft ties on the frame sructure you describe wouldnt be enough unless you have a staggered system, which im guessing would mean a tie every 3rd frame vertically shifting a bay on each lift. System scaffs over here are Leyher and haki. You coud google for technical info. What do your fellow engineers say when you question the efficiency of there calcs? good luck Yanchorman.sorry couldnt resist.:bigsmile:

Tube_N_Clamp
20th October 2011, 11:40 PM
Send me a private message i'll give you some spects on OSHA requirements on tie offs.