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Small-Amplitude Vibration Tests of a Full-Scale RC Flat-Plate Structure. By: Luis Arboleda. MSCE Thesis. Problem Definition. Hypothesis. “The natural frequencies and lateral stiffness of a 3D RC flat-plate structure can be estimated using a conventional 2D frame analysis”. Specimen. α.
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Small-Amplitude Vibration Tests of a Full-Scale RC Flat-Plate Structure By: Luis Arboleda MSCE Thesis
Hypothesis “The natural frequencies and lateral stiffness of a 3D RC flat-plate structure can be estimated using a conventional 2D frame analysis”
α Exterior Interior 0.35-0.60 0.55-0.85 Pecknold (1975) Allen and Darvall (1977) 0.65 0.45 0.50 0.65 Banchik (1987) Hwang and Moehle (1993) 0.15-0.40 0.20-0.65 Literature Review
Elevation View Plan View Test Setup 15
1.32 1.27 2.09 1.98 1.69 1.58 86 79 1.20 1.16 2.09 1.98 1.34 1.30 86 79 f and k for Ec= 3800 ksi
Length 0.5% Check as-built dimensions Width 0.5% Depth 0.9% ? Ec Variables to Calculate k 7
1.19 1.14 2.09 1.98 1.36 1.27 86 79 1.08 1.05 2.09 1.98 1.09 1.05 86 79 f and k for Ec= 4700 ksi 1.32 1.20
1.08 1.04 2.09 1.98 1.12 1.05 86 79 0.98 0.95 2.09 1.98 0.90 0.87 86 79 f and k for Ec= 5700 ksi 1.19 1.08
α 2D Frame Analysis Exterior Frames Interior Frames 2.09 1.98 86 79 α for Ec= 4700 ksi 0.5
α 2D Frame Analysis Exterior Frames Interior Frames 2.09 1.98 86 79 α for Ec= 5700 ksi 0.3
Is it plausible that Ec is larger than 3800 ksi?
CYLINDER C-3 EC,ASTM= 3950 ksi Ec of the Flat-Plate Structure Ecmean= 4000 ksi 6
Free-Vibration Tests 15 Tests, 6L, 9M
Conclusions • The secant modulus of concrete can be larger than 1.25× EC,ACI (or 1.2 × EC,ASTM) for σ< fC’/15. • α= 1/2 can be used to model a 3D flat-plate structure using 2D frame analyses. • (It was obtained assuming EC= 1.25 × EC,ACI).