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Individual directional results are automatically combined by CQC. And orthogonal loading effects are combined with SRSS.

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90% of mass participation ratio is automatically controlled and reported by the program.

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Number of Modes

The natural modes of vibration for the structure is are determined by structural analysis. A sufficient number of modes are obtained, a combined modal mass participation of % 100 of the structure’s mass. The analysis is permitted to include a minimum number of modes to obtain a combined modal mass participation of at least 90% of the actual mass in each orthogonal horizontal direction of response considered in the model.

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Modal Response Parameters

The value for each forceForce-related design parameter of parameters, such as story drifts, support forces, and individual member forces for each mode of response, is are computed using the properties of each mode, and the response spectra defined in either Section 11.4.6 or 21.2 are divided by the quantity R ∕ Ie. The value for displacement Displacement values and drift quantities is are multiplied by the quantity Cd ∕ Ie.

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Combined Response Parameters

The value for each parameter calculated for the various modes is combined using the square root of the sum of the squares (SRSS) method, the complete quadratic combination (CQC) method.

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