Structural Frame Sequence and Stability

The structural frame erection sequence determines how and when each element is installed to maintain stability.
Deviating from the designed sequence can leave the frame partially complete and vulnerable to collapse.
Temporary bracing must remain in place until the permanent stability system is fully connected.
Wind loading on a partially erected frame is a major collapse risk, especially during overnight periods.
Concrete frames require formwork and propping sequences that match the structural engineer design intent.
Steel frames need bolted or welded connections completed in the correct order to develop stability.
Precast frames rely on connection grouting, stitching, and tie installation to achieve their designed strength.
The temporary works coordinator must approve any change to the designed erection sequence before work proceeds.
BS 5975 and CDM 2015 require that frame erection is planned, managed, and supervised by competent persons.
Frame collapses during erection have caused multiple fatalities on UK construction sites.

Prevent collapse	Partially erected frames are inherently unstable. Wrong sequencing or missing bracing has caused fatal collapses.
Design intent	The frame sequence is engineered to maintain stability at each stage. Deviating from it removes safety margins.
Legal requirement	CDM 2015 requires structural frame erection to be planned and supervised, with temporary works formally managed.

Do

Don't

Follow the designed erection sequence for every frame element without deviation.
Install temporary bracing as specified and keep it in place until authorised removal.
Complete bolted or welded connections in the correct order to develop stability.
Obtain TWC approval before making any changes to the frame erection sequence.
Monitor weather forecasts and secure partially erected frames before adverse conditions.
Inspect the frame daily for movement, deflection, or connection defects.
Brief the erection team on the day's sequence and any critical hold points.
Ensure precast connections are grouted and cured before removing temporary props.
Record each stage of erection and confirm stability before proceeding further.
Maintain exclusion zones below frame erection areas to protect workers at ground level.

DON'T change the frame erection sequence without written approval from the TWC.
DON'T remove temporary bracing until the permanent stability system is complete.
DON'T leave a partially erected frame overnight without checking stability and bracing.
DON'T continue erection in high winds that exceed the designed working limits.
DON'T skip connections or leave bolts loose to save time during erection.
DON'T load the frame with materials before the designed stage of completion.
DON'T allow workers under the erection area without exclusion zones in place.
DON'T strip formwork or propping from concrete frames before the specified cure time.
DON'T assume the frame is stable because individual elements feel rigid.
DON'T proceed past hold points without inspection and formal sign-off.

See also: Temporary Bracing and Stability | Temporary Works Coordinator Role

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