CQC modal combination rule for high‐frequency modes

Department of Civil Engineering, University of California, Berkeley, CA 94720, U.S.A.
Earthquake Engineering & Structural Dynamics (Impact Factor: 1.95). 11/1993; 22(11):943 - 956. DOI: 10.1002/eqe.4290221103

ABSTRACT The CQC rule for modal combination is extended to include the quasi-static contribution of truncated modes and the effects of input narrow-bandedness and cut-off frequency. A simple measure of the error in approximating a high-frequency modal response by its quasi-static contribution is derived. The extended rule is applicable to structures with high-frequency modes and to seismic inputs which may not be regarded as wide band. Numerical examples demonstrate the significance of input bandwidth and cut-off frequency on modal cross-correlation coefficients, and on the error resulting from truncation of high-freqeuncy modes.

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    ABSTRACT: An evaluation was made of some modal maxima superposition rules, currently used to estimate the response of buildings subjected to earthquake excitations: the square root of the sum of the squares (SRSS) method, the complete quadratic combination (CQC) method, and the double sum combination (DSC) method. A response spectrum analysis was performed using the DAMB computer program. The results obtained with these three methods of modal combination for the multi-storey shear wall building, regular and irregular were compared. Streszczenie: W pracy przedstawiono porównanie wyników wybranych metod superpozycji maksimów modalnych, stosowanych przy szacowaniu odpowiedzi budynków, poddanych wpływom sejsmicznym i parasejsmicznym: SRSS (Square Root of the Sum of Squares), CQC (Complete Quadratic Combination) i DSC (Double Sum Combination). Do obliczeń metodą spektrum odpowiedzi wykorzystano system programów DAMB. Pokazano różnice w uzyskiwanych przy zastosowaniu wymienionych trzech algorytmów wartościach oszacowań maksymalnych przemieszczeń i sił tnących w pasmach nadproży dla wielokondygnacyjnego budynku o konstrukcji ścianowej, regularnego i nieregularnego.
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    Journal of Structural Engineering 04/2000; 126(4). DOI:10.1061/(ASCE)0733-9445(2000)126:4(467) · 1.49 Impact Factor
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