ABCDEFGHIJKLMNOPQRSTUVWXYZ
1
Daniel
2
PROJECT : PAGE :
3
T. LiCLIENT :
DESIGN BY :
4
JOB NO. : DATE :
REVIEW BY :
5
Design of PT Slabs on Expansive Soil Ground Based on Specification of PTI
6
7
1. DESIGN METHODS
8
1.1
DIVIDE AN IRREGULAR FOUNDATION PLAN INTO OVERLAPPING RECTANGLES AND USING
9
THIS SPREADSHEET DESIGN EACH RECTANGULAR SECTION SEPARATELY.
10
11
2. INPUT DATA & DESIGN SUMMARY
12
2.1 SOILS PROPERITIES
13
ALLOWABLE SOIL-BEARING PRESSURE
qallow=2700psf
14
EDGE MOISTURE VARIATION DISTANCE
em=5.5
ft, for center lift
15
=2.5
ft, for edge lift
16
DIFFERENTIAL SOIL MOVEMENT
ym=3.608
in, for center lift
17
=0.752
in, for edge lift
18
SLAB-SUBGRADE FRICTION COEFFICIENT
m=0.75
19
2.2 STRUCTURAL DATA AND MATERIALS PROPERITIES
20
SLAB LENGTHL=42ft
21
SLAB WIDTHB=24ft
22
SLAB THICHNESS
t=4in
23
PERIMETER LOADING
P=1040plf
24
MAX BEARING LOADING ON THE SLAB
Pb=2700plf
25
ADDED DEAD LOAD
DL=15psf
26
LIVE LOADLL=40psf
27
AVERAGE STIFFENING BEAM SPACING, L DIRECTION
SL=14ft
28
AVERAGE STIFFENING BEAM SPACING, B DIRECTION
SB=12ft
29
STIFFENING BEAM DEPTH
h=24in
30
STIFFENING BEAM WIDTH
b=10in
THE DESIGN IS ADEQUATE.
31
CONCRETE STRENGTH
f'c=2.5ksi
SUGGESTED RATIO OF EXPECTED ELONGATION IS 0.00777
32
SLAB PRESTRESSING TENDONS, L DIRECTION
5tendons w/0.153
in2 at each tendon.
CONVERTED UNIFORM THICKNESS IS 6.48 inch
33
SLAB PRESTRESSING TENDONS, B DIRECTION
7tendons w/0.153
in2 at each tendon.
34
TENDON IN THE BOTTOM OF EACH BEAM
0tendons w/0
in2 (only for edge lift governing required)
35
EFFECTIVE PRESTRESS AFTER ALL LOSSES EXCEPT SG
fe=174ksi
36
37
3. ASSUME A TRIAL SECTION
38
3.1 ASSUME BEAM DEPTH AND SPACING
39
ALLOWABLE DIFFERENTIAL DEFLECTION, FOR CENTER LIFT, AT L DIRECTION
ALLOWABLE DIFFERENTIAL DEFLECTION, FOR CENTER LIFT, AT B DIRECTION
40
Dallow = 12 MIN(L, 6b) / CD =
1.40in
Dallow = 12 MIN(B, 6b) / CD =
0.80in
41
Whereb =8ftWhereb =8ft
42
CD =360
ft, Table 18-III-GG
CD =360
ft, Table 18-III-GG
43
ALLOWABLE DIFFERENTIAL DEFLECTION, FOR EDGE LIFT, AT L DIRECTION
ALLOWABLE DIFFERENTIAL DEFLECTION, FOR EDGE LIFT, AT B DIRECTION
44
Dallow = 12 MIN(L, 6b) / CD =
0.70in
Dallow = 12 MIN(B, 6b) / CD =
0.40in
45
Whereb =8ftWhereb =8ft
46
CD =720
ft, Table 18-III-GG
CD =720
ft, Table 18-III-GG
47
BEAM DEPTH, FOR CENTER LIFT, AT L DIRECTION
BEAM DEPTH, FOR CENTER LIFT, AT B DIRECTION
48
h = [(ym L)0.205 SB1.059 P0.523 em1.296 / 380 Dallow ]0.824 =
14.28in
h = [(ym B)0.205 SL1.059 P0.523 em1.296 / 380 Dallow ]0.824 =
23.57in
49
BEAM DEPTH, FOR EDGE LIFT, AT L DIRECTION
BEAM DEPTH, FOR EDGE LIFT, AT B DIRECTION
50
h = [L0.35 SB0.88 em0.74 ym0.76 / 15.9 Dallow P0.01]1.176 =
2.51in
h = [B0.35 SL0.88 em0.74 ym0.76 / 15.9 Dallow P0.01]1.176 =
4.52in
51
GOVERNING h =
23.57in <ACTUAL h =24.00in
[Satisfactory]
52
3.2 DETERMINE SECTION PROPERTIES
53
L DIRECTIONB DIRECTION
54
n =3yb =17.89inn =4yb =18.59in
55
A =1752in2St =12824in3A =2816in2St =20674in3
56
I =78347in4Sb =4379in3I =111827in4Sb =6015in3
57
CGS =22.00ine =4.11inCGS =22.00ine =3.41in
58
(F32*(H21*12/H32)*(H29-2)+F33*C53*3.25)/(F32*(H21*12/H32)+F33*C53)
59
4. CALCULATE MAXIMUM APPLIED SERVICE MOMENTS
60
4.1 CENTER LIFT MOMENT AT L DIRECTION
CENTER LIFT MOMENT AT B DIRECTION
61
ML = A0 (B em1.238 + C) =
11.51ft-kips / ft
MB = (58 + em) ML / 60, for L /B > 1.1
=12.18ft-kips / ft
62
Where
A0 = (L0.013 SB0.306 h0.688 P0.534 ym0.193) / 727 =
1.439
MB = ML, for L /B < 1.1
63
64
B = 1, for em < 5
=0.87
65
B = MIN[(ym - 1) / 3, 1], for em > 5
66
67
C = 0, for em < 5
=0.83
68
C = MAX{[8 - (P - 613) / 255] (4 - ym) / 3], 0}, for em > 5
69
70
4.2 EDGE LIFT MOMENT AT L DIRECTION
EDGE LIFT MOMENT AT B DIRECTION
71
ML = SB0.10 (h em)0.78 ym0.66 / (7.2 L0.0065 P0.04) =
2.66ft-kips / ft
MB = h0.35 (19 + em) ML / 57.75, for L /B > 1.1
=3.01ft-kips / ft
72
MB = ML, for L /B < 1.1
73
74
5. CHECK FLEXURAL CONCRETE STRESSES
75
5.1 ALLOWABLE CONCRETE STRESSES
76
FLEXURAL TENSILE STRESS
ft,allow = - 6 (fc')0.5 =
-0.300ksi
77
FLEXURAL COMPRESSIVE STRESS
fc,allow = - 0.45 fc' =
1.125ksi
78
79
5.2 TOP STRESS, FOR CENTER LIFT MOMENT, AT L DIRECTION
TOP STRESS, FOR CENTER LIFT MOMENT, AT B DIRECTION
80
f= Pr / A - ML / St + Pr e / St =
-0.172ksi0.011892183630.034675958810.0930715812
f = Pr / A - MB / St + Pr e / St =
-0.219ksi
81
Where
Pr = Pe - SG =
97.65kipsWhere
Pr = Pe - SG =
150.89kips
82
Pe = fe Aps =
133.11kips
Pe = fe Aps =
186.35kips / ft
83
SG = Wslab m / 2000 =
35.46kips
SG = Wslab m / 2000 =
35.46kips
84
85
Then f>ft,allow
[Satisfactory]
Then f>ft,allow
[Satisfactory]
86
<fc,allow
[Satisfactory]
<fc,allow
[Satisfactory]
87
88
5.3 BOTTOM STRESS, FOR CENTER LIFT MOMENT, AT L DIRECTION
BOTTOM STRESS, FOR CENTER LIFT MOMENT, AT B DIRECTION
89
f = Pr / A + ML / Sb - Pr e / Sb =
0.721ksi
f = Pr / A + MB / Sb - Pr e / Sb =
0.989ksi
90
91
Then f>ft,allow
[Satisfactory]
Then f>ft,allow
[Satisfactory]
92
<fc,allow
[Satisfactory]
<fc,allow
[Satisfactory]
93
94
5.4 TOP STRESS, FOR EDGE LIFT MOMENT, AT L DIRECTION
TOP STRESS, FOR EDGE LIFT MOMENT, AT B DIRECTION
95
f = Pr / A - ML / Sb - Pr e / Sb =
-0.211ksi
f = Pr / A - MB / Sb - Pr e / Sb =
-0.284ksi
96
97
Then f>ft,allow
[Satisfactory]
Then f>ft,allow
[Satisfactory]
98
<fc,allow
[Satisfactory]
<fc,allow
[Satisfactory]
99
100
5.5 BOTTOM STRESS, FOR EDGE LIFT MOMENT, AT L DIRECTION
BOTTOM STRESS, FOR EDGE LIFT MOMENT, AT B DIRECTION