この記事の内容
この記事の本文は英語版を掲載しています。日本語訳は準備中です。
World Steel builds the lift and stair core walls of multi-storey office blocks with climbing formwork, which rises with each pour and is anchored into the concrete of the previous lift. The system gives an even wall finish, a steady floor-by-floor cycle and safe working platforms on both the inside and the outside of the core.
Striking and climbing sequence
| Step | Work |
|---|---|
| 1–3 | Remove the edge ties, corner ties and anchor bolts of the previous lift. |
| 4–6 | Remove the anti-slip and corner-locking wedges; turn the struts to open the formwork corners; turn the gear to slide the formwork away from the wall. |
| 7–9 | Strike the inner formwork, remove the anchor boxes used for the inner platform, and remove the wind bracing. |
| 10–12 | Remove the safety pins at the anchors before lifting; lift the platform off the old anchors; set it on the new anchors and fit the safety pins before releasing the crane slings. |
| 13 | Refit the wind bracing. |
Setting the formwork for the next pour
| Step | Work |
|---|---|
| 14 | Accept the wall reinforcement already fixed. |
| 15–17 | Position and grease the anchor boxes on the formwork; apply release oil to the panel faces; position the anchor bolts. |
| 18–19 | Check survey levels and formwork verticality. |
| 20–21 | Adjust the jacks; tighten the formwork foot ties once in position (check that the stops are inside the formwork before tightening). |
| 22–25 | Move the formwork against the wall; adjust the corner opening; drive home the corner and travel wedges. |
| 26–27 | Tighten the corner and edge ties, and accept the formwork before concreting. |
Points to watch
- Choose the anchor positions for the first pour so that, on typical floors, each pour covers exactly one storey, floor to floor.
- Keep anchor bolts clear of doors and openings, especially in the last pours of the typical floors; provide the full number of anchors as designed.
- Release the wedges before moving the frame and opening the corners, and avoid excessive force that can damage the connections.
- Grease the anchor boxes and seal the threaded plugs before the pour so they can be removed easily.
- After lifting to the new position, fit the safety pins and the wind bracing before releasing the crane slings.
- Close all gaps in the working platforms to protect people below; provide guardrails; inspect and maintain the access ladders regularly.
Common mistakes
| Mistake | Consequence | Prevention |
|---|---|---|
| Anchor bolts at doors or openings | Next lift cannot be anchored | Check the architectural drawings when setting anchors |
| Anchor boxes not greased or plugs not sealed | Anchor boxes cannot be removed | Include in the formwork acceptance record |
| Crane slings released before safety pins are fitted | Risk of the platform falling | A defined lifting sequence with a supervisor present |
| Gaps in the working platform | Objects falling to the area below | Inspect before every climb |
Reference standards
The edition in force when the contract is signed applies.
- TCVN 4453:1995 Monolithic concrete and reinforced concrete structures – Code of practice for construction and acceptance
- TCVN 5308:1991 Code of practice for safety in construction
