Formwork stripping sequence in multi-storey construction: which parts are removed first to ensure safety and quality?

Introduction / Context:
Formwork removal (stripping) in multi-storey buildings must follow a safe sequence to prevent overstressing fresh concrete and to avoid collapse or excessive deflection. Site engineers must remember which elements can be removed early and which require longer curing and strength gain.

Given Data / Assumptions:

• Normal Portland cement concrete under typical ambient conditions.
• Formwork to columns, beams, and slabs with adequate propping and reshoring practices.
• Standard practice: remove non-load-carrying parts first.

Concept / Approach:
Sides (web formwork) of beams and girders do not carry significant vertical reactions once the concrete has set; they primarily shape the member. Hence, they can be removed earlier. Soffits (bottom forms) of beams and slabs continue to support self-weight and construction loads; their removal is delayed until sufficient strength is achieved. Column forms, though vertical, typically remain until enough strength allows safe removal without damaging edges or cover.

Step-by-Step Solution:
Identify non-load-carrying formwork: side forms of beams/girders.Retain load-carrying formwork: soffits and props to beams/slabs.Therefore, remove sides of beams and girders first; delay soffits and column forms as per code/strength checks.

Verification / Alternative check:
Concrete codes and site handbooks prescribe earliest removal for side forms, with specific minimum times/strength for soffits and props (often tied to cube strength percentages).

Why Other Options Are Wrong:

• Bottom of beams/girders: still load-bearing early on.
• Column forms: premature removal can cause edge damage and instability.
• All at the same time: unsafe, violates staged stripping principles.

Common Pitfalls:

• Confusing set time with strength gain; removal depends on strength, not just hours elapsed.

Final Answer:
sides of beams and girders