Jun 28th, 2019 | Categories: news
The Safety Technical Regulation required that the assemble height can not over 24m when scaffolding is used to assemble two rows. While what factors will influence the height?
There are three main factor
The loading of the scaffolding in out wall.
Assemble type of scaffolding in out wall.
Coordination with other scaffolding regulation.
The scaffolding loading includes scaffolding self weight, accessory weight, worker’s construction loading and wind loading.
1.1 Does not consider the wind loading.
1.2 Consider wind loading.
The scaffold standard vertical and ledger size is 2.0x0.9m and standard span is 2m for out wall scaffolding. Diagonal brace should be prepared each five span.
Below is the calculation for standard, which required in the Safety Technical Regulation: h--the maximum span on vertical part for scaffolding ledger; u-- standard calculating rate considering system steady, which is confirmed by below chart.
B type scaffolding standard length and thickness ratio λ=l0/i=182.4＜210, then standard steady rate φ=0.158 after checking.
Based on above condition, let’s check is it reasonable to assemble the out wall scaffolding lower than 24m.
Imagine the out wall scaffolding assembled to 24m,
3.1 then scaffolding weight NG1K= base jack + standard + ledger + diagonal brace = 4.32 kN
3.2 Accessory weight NG2K= steel plank weight 0.35 kN/m2 × 11 floors working platform = 3.47kN
3.3 Labor construction loading (working platform can not over 2 floors) NQK = labor construction loading 2.0 kN/m2 × 2floors working platform = 3.60 kN
3.4 Bending ratio of wind loading on standard part
3.4.2 Consider wind loading
Checking from above result, when out wall scaffolding is assembled to 24m, it is similar to the design rate when consider the wind loading.
Then the Safety Technical Regulation required height is reasonable.
When out wall scaffolding is over 24m, we can reduce the span or increase the wall tie to increase the standard loading, or reducing some working amount to reduce the total system loading.