diseño columnas de n pisos(7)
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Transcript of diseño columnas de n pisos(7)
![Page 1: diseño columnas de n pisos(7)](https://reader030.fdocuments.ec/reader030/viewer/2022020101/55298f83550346482e8b47f6/html5/thumbnails/1.jpg)
PROBLEMA: diseñar las columnas cargadas en terreno gravoso con flexión uniaxial de un edificio de 8 pisos cuya estructura se muestra en la figura.F`c= 280Kg/cm2.
Columnas:
• Tipo I = 8 columnas• Tipo II = 2 columnas• Tipo III = 2columnas• Tipo IV = 2columnas
I I
I
I I
II
II
I
I
I
III
III
IV
IV
4m 4m
3m
3m
3m
4m
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TC T carga P (TN)M1
(t-m)
M2
(t-m)Condición de carga
Pu(Tn)
M1
(T-m)
M2
(T-m)e/h
I
D 60 1.40 3.60
L 20 1.10 2.80 0.75(1.4D+1.7L+1.7W) 114 8.10 12.58 0.245
W 20 4.10 4.10
II
D 110 1.40 3.10
L 39 1.10 2.50 0.75(1.4D+1.7L+1.7W) 165.2 11.67 15.24 0.205
W 0 6.90 6.90
III
D 110 2.70 7.10
L 39 2.10 5.50 0.75(1.4D+1.7L+1.7W) 190.7 10.74 19.69 0.229
W 20 4.10 4.10
IV
D 165 6.00 6.00
L 58 4.70 4.70 0.75(1.4D+1.7L+1.7W) 247.2 13.64 21.09 0.171
W 0 6.90 6.90
Cargas ultimas de diseño:
(*): e = M2
h Pu. te/h = 12.58/ 114 x 0.45 = 0.245
t = en metros
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TIPO COLUMNA Pu M1 M2 e/h (*)
I 0.45 X 0.45 114 8.10 12.58 0.245
II 0.45 X 0.45 165.2 11.67 15.24 0.205
III 0.45 X 0.45 190.7 10.74 19.69 0.229
IV 0.50 X 0.50 247.2 13.64 21.09 0.171
CUADRO DE RESUMEN:
Cm = 0.6 + 0.4(M1) M2
Cm = 0.6 +0.4(8.10/12.58) = 0.856 = 1.00
Pu = 8(114) + 2(165.2) + 2(190.7) + 2(247.2)
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Tipo EC.Ig/Lc C A K d 10-5 x ( /K. Lu)2 EI x 107 PC
I 1.72 1.156 1.49 1.39 0.300 1.518 2.639 400
II 1.72 2.312 0.74 1.28 0.213 1.791 2.828 506
III 1.72 1.156 1.49 1.39 0.378 1.518 2.489 378
IV 2.61 2.312 1.13 1.33 0.298 1.659 4.028 668
Longitudes efectivas de columnas y cargas de Euler:
Pc = 4412.8
Pu = 2118,2 Pc = 6304 = 0,7(estribados)
= Cm ……… 1 - ( Pu/ Pc)
=1.923
B = 1.0
Cm = 1.00
EC = 15 (280)1/2 =251 Kg./cm2 Lc = 6m ; Lu = 580 cmIg = t4 (cm4)
E I = Ec. t4…………
30(1 + βd)
Pc = 8(400)+2(506)+2(378)+2(668) = 6304
Para tipo “L”: βd = 0.75(1.4)D/M2 = 0.75x1.4(3.6)/12.58 = 0.300
D = M2 (inicial)
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Tipo Columna EI Pu(Tn)
().e/h g K tASt Refuerzos
I 45*45 2.639 114 0.471 0.71 0.224 0.011 22.27 6 7/8”
II 45*45 2.828 165.2 0.394 0.71 0.325 0.021 42.53 8 1”2 ½”
III 45*45 2.489 190.7 0.440 0.71 0.375 0.027 54.68 6 1¼”2 7/8”
IV 50*50 4.028 247.2 0.329 0.74 0.353 0.042 105 6 1 ½”2 1 3/8”
DISEÑO (ACI – SP 17A)
6 7/8” = 23,22 >22,27
8 1” = 40.562 ½” = 2.54 43.1 > 42.53
61 ¼” = 47,5227/8” = 7.74 55.26 > 54.68
81 ½” = 91.221 ¼” = 15.84 107.04 > 105
=1.923
e/h 0.2450.2050.2290.171
K = Pu/(F`c)(b x t) Pu = Kg.b = cmt = cm
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GRAFICA DE PERFILES:
Tipo I
6 7/8”
Tipo II
8 1”
2 ½”
Tipo III
6 1¼”
2 7/8”
Tipo IV
6 1 ½”
2 1 3/8”