Estructur

* Diseñar una zapata combinada para las dos columnas mostradas en la figura con los datos siguientes :
σadm = 4klb/ft²
f ’c= 3000 lb/in² MD(c-1) = 10 Ton Ml=(8Ton)
f ’y= 60 klb/in² MD(c-2)= 6 Ton Ml= (6Ton)
columna 50*50 cm PD= 120klb PL= 100 klb
columna 55*55 cm PD= 200klbPL= 150 klb
Pt = 6 Ton ME= I 16 Ton – m HF= 2m
σadm = 4 klb klb in² x 1000lb 1 klb x 4000lbin² x 1 klb2.2lb =19.6Tm²
σadm = 19.60 – (2x2) = 15.60Tm²
A = 1.5 (54.54 Ton + 90.72 +45.36 +68.04)15.60 = 24.87 m²
L= A = L =24.87 = 4.99 m = 5m
Luego L6 = 56 = 0.83m
m = 14 + 16 = 30 Tm A= 6x4.15=24.90
P total =PD + PL + PSZ’
PSZ= δprom x A x HF
PSZ= 2(6x4.15) (2) = 99.60 Ton
P total = (219.66 + 99.60) = 319.26 Ton
e = 30/319.26 = 0.09
σ max: (P totalAREA ) ( 1+ 6eL)
σ max: (319.2624.90) ( 1+6x0.096) = 13.97
σ max < σ adm
13.97 <19.60
-Calculo condicion accidental
Pt= PD+PL+PT+PSZ
Pt= (219.66+99.60+6) = 325.26
MT= 14+16+16=46
E= M²/ PT = 46/325.26 = 0.14
PT =219.66 +99.60 – 6 =313.26
MT =14+16-16=14
e= 14/313.26= 0.04< L6
Esfuerzo max
σ max = PtA (1+6 eL)
σ max =( 325.226(6X 4.15) ) (1+6 X 0.146) = 14.89
σ adm> σ max
σ suelo = σ adm x 1.33= 19.60 x 1.33 = 26.07 Tm²
-Calcular presiones ultimas
Pu= 1.2D+1.6L
Pu= 1.2(54.54+90.72) +1.6 (45.36+68.04)
Pu= 355.62 Ton
Mu = 1.2(16) + 1.6(14) = 41.60Ton-me=41.60/355.62 = 0.12 L/6
σ max grav= (Ptotal Area)(1+6eL)
= (355.62 (6x4.15))(1+6x0.12L)
= (15.99 T/m²<26.07Tm²

-Calcular de σ minimo
σ minGrav=355.62(6x4.15) (1- 6x0.126)
=12.57 T/m²
σ sz = 1.2 pszArea = 1.2x 99.606x4.15 4.80 T/m²

12.57 4.80...