An improved multidimensional MPA procedure for bidirectional earthquake excitations.
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Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA) method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two components earthquake excitations, and independent analysis in each direction is not required and the application of simplified superposition formulas is avoided.The strength reduction factor spectra based on superposition of earthquake excitations are discussed and compared with the traditional strength reduction factor spectra.The step-by-step procedure is proposed to estimate seismic demands of structures.
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Affiliation: College of Architecture & Civil Engineering, Dalian Nationalities University, Dalian 116600, China.
ABSTRACT
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Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA) method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two components earthquake excitations, and independent analysis in each direction is not required and the application of simplified superposition formulas is avoided. The strength reduction factor spectra based on superposition of earthquake excitations are discussed and compared with the traditional strength reduction factor spectra. The step-by-step procedure is proposed to estimate seismic demands of structures. Two examples are implemented to verify the accuracy of the method, and the results of the examples show that (1) the IMMPA method can be used to estimate the responses of structure subjected to bidirectional earthquake excitations. (2) Along with increase of peak of earthquake acceleration, structural response deviation estimated with the IMMPA method may also increase. (3) Along with increase of the number of total floors of structures, structural response deviation estimated with the IMMPA method may also increase. Related in: MedlinePlus |
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Mentions: In order to clarify how the proposed methodology should be applied, two simple analytical examples are presented. The structures considered are a 10-storey and a 15-storey eccentric reinforced concrete frame buildings, as illustrated in Figure 4. It is considered that the ground motion is acting simultaneously along the two horizontal axes. Each floor has three degrees of freedom (DOF) defined at the center of mass (CM). Each floor diaphragm is rigid in its own plane and the center of stiffness (CS) deviates from the CM. The dimensions of the two buildings in height are 3.6 m for all stories, and the dimensions in plane are shown as Figure 4. For the 10-storey building, the sectional sizes of beams are 300 × 700 mm2 for 2th~11th floor; the sectional sizes of columns are 700 × 700 mm2 for 1th~3th storey, 600 × 600 mm2 for 4th~7th storey, and 500 × 500 mm2 for 8th~10th storey. For the 15-storey building, the sectional sizes of beams are 300 × 700 mm2 for 2th~5th floor, 300 × 650 mm2 for 6th~11th floor, and 300 × 600 mm2 for 12th~16th floor; the sectional sizes of columns are 700 × 700 mm2 for 1th~4th storey, 650 × 650 mm2 for 5th~10th storey, and 500 × 500 mm2 for 11th~15th storey. Steel ratios are approximately 1.5% for beam sections and 2% for column sections of the two buildings. Concrete compression strength is selected as 30 MPa for all columns and beams of the structure. The design dead load and live load are, respectively, 6.6 kN/m2 (4.7 kN/m2) and 1.0 kN/m2 (2.0 kN/m2) for each floor (roof). The damping of the building is modeled by the Rayleigh damping, and damping ratio ξ equals 5%. |
View Article: PubMed Central - PubMed
Affiliation: College of Architecture & Civil Engineering, Dalian Nationalities University, Dalian 116600, China.