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Modal response analysis specified in 12.9.1 is done automatically.
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In accordance with 12.9.1.1, the sufficient number of vibration modes to be taken into account is calculated automatically as 90%. |
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With the modal response analysis, seismic effects are combined automatically by CQC. |
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Symbols
m i = total mass of the i'th storey
m iθ = mass moment of inertia of the i'th storey
m ixn (X) = (X) for the earthquake direction, the i'th storey modal effective mass of the nth natural vibration mode of the building in the x-axis direction
m iyn (X) = (X) for the earthquake direction i'th storey modal effective mass
m iθn (X) = (X) of the building's nth natural vibration around the z-axis for the earthquake direction i'th storey modal effective mass moment of inertia
m j (S) = Finite Element Analysis node j to effect individual masses
m txn (X) = (X) earthquake direction for building the x-axis direction of the nth vibration mode of base shear modal effective mass
m tyne (Y) = (Y) earthquakes base shear in the building along the y axis for the direction of modal effective mass
r max (X) = (X) earthquake direction for any behavior variables (displacements and relative storey drift, strain component) corresponding to the coupled typically to maximum modal behavior of size
r n (X) = Typical unit modal behavior magnitude corresponding to any action magnitude (displacement, relative floor displacement, internal force component) for the earthquake direction in the nth natural vibration mode (X),
r n, max (X) = nth natural vibration mode ( X) Typical largest modal behavior magnitude corresponding to any action magnitude (displacement, relative floor displacement, internal force component) for the earthquake direction
S aR (T n ) = reduced design spectral acceleration for the nth vibration mode
T n = nth mode natural vibration period
β mn = ratio of mth and nth natural vibration periods
Φi (X) n = nth natural vibration mode shape amplitude at i'th storey (X) earthquake direction
Φ ixn =nth natural vibration mode shape amplitude ati'th storey in x-axis direction
Φ iyn = y-axis at i'th storey nth natural vibration mode shape amplitude in the direction
θ iθn = nth natural vibration mode shape amplitude as rotation around the z-axis at the ith storey
Γ x (X) = (X) for the earthquake direction, modal contribution of the nth vibration mode multiplier
ξ n = modal damping ratio of the nth vibration mode
ω n = Natural vibration angular frequency of the nth vibration mode
ρ mn = Cross correlation coefficient of the mth and nth natural vibration modes in the Complete Quadratic Combination Rule
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Modal response parameters are the magnitudes calculated according to the information obtained only in the direction of the earthquake considered and from the free vibration response of the structural system, regardless of the earthquake data. Modal response parameters are defined only for the (X) direction in this document. The same parameters are made for the (Y) direction. In the definition of modal response parameters, the degrees of freedom of the structural system are determined according to the defined masses. In case story floors are modeled as rigid diaphragm, the story mass is collected at the center of mass of the relevant floor. If story slabs are modeled as semi-rigid diaphragms, the masses are defined at the joints of Shell Finite Elements. In this case, instead of a total story mass, mThe masses of j (S) are taken into account.
Combined Response Parameters
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