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4.1.8.11.(8)
OS2OP2OS2OP2
ObjectiveOS2 Structural Safety
Attribution
(a) [F20-OS2.1]
Application
Application 1: 
Torsional effects in buildings due to eccentricity between the centres of mass and resistance, and the dynamic amplification of the torsional motion.
Exceptions: 
except as stated in Sentence 4.1.8.1.(1), which applies to areas where the spectral response acceleration amplified for site conditions equals the floor levels found in low seismicity regions with Site Class C (i.e. very dense soil and soft rock).
This applies to buildings described in Sentence 1.3.3.2.(1) of Division A and to buildings to which Part 9 applies [see Sentence 1.3.3.3.(1) of Division A for application of Part 9] that are required to be designed in accordance with the requirements of Part 4.
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Intent
Intent 1: 
To limit the probability that the calculation of loads due to earthquake will not take into account the forces due to expected seismic torsional moment at any level of the building, taking into account eccentricities between the centre of mass and the centre of rigidity and their dynamic amplification, which could lead to structural failure, which could lead to harm to persons.
Intent 2: 
To clarify that torsional effects are to be addressed concurrently with the static loads determined in Sentence 4.1.8.11.(6).
Intent 3: 
To direct Code users to Sentence 4.1.8.11.(10) for the calculation of torsional loads.
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