1. Roustness
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2. Robustness – When?
Robustness requirements – are relevant for all buildings, but:
CC3: For buildings with a high consequence class there is requirements to provide documentation for robustness.
CC2: For building with a medium consequence class, an evaluation of robustness should be provided.
CC1: where as there are no requirements for building with a low consequence class.
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3. Robustness – how?
At least on of the following criteria must be fulfilled according to EC0/NA:
By verifying that the essential parts of the structure i.e. key members, have low sensitivity to unintended effects and defects
By verifying that no extensive failure of the structure occurs if a limited part of the structure fails (loss of a member- Bortfald af element)
By verifying sufficient safety of key members , such that the level of system safety as an equivalent structure for which the robustness is documented by verification of sufficient safety in the event of the loss of member.
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4. Loss of a member Design of robustness by ”loss of a element”
Guidelince for buildings up to 15 stories:
The acceptable extent collapse may be taken as 15 % of the floor space of two consecutive storeys but not more than 240 m2 per storey and not more than 360 m2 in total
Assuming the following of the collapse:
Loss of a limited part of a given column and an associated floor area
Loss of a limited part of a given 3 m length wall with an associated floor area
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5. Key elements Robustness with extra safety factor on key elements
Increasing the paterial factor on material strength by 1,2
Every effert should be made to in the design to document the robustness of a structure as far as possible without the use of incresed safety factors
Where safety factor are used on key members, it should however be ensured that the resistance of the structure to unintended effects and defects is actually increased
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6. loss of a member CC3 - Example
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7. loss of a member CC3 - Example
Determine T and the biggest shear force in the connection between the wall and the deck:
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8. Robustness + Vertically ties N:7,5kN/m, min 40kN H:15kN/m, min 80kN
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9. Horizontal ties between walls and floors - EC2
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11. Link2:
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12. Link:
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