Design Of Conventional Slabs On Compressive Soil Grade Based On ACI 360 Spreadsheet (www.theengineeringcommunity.org).xlsx

	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O
1	Design of Conventional Slabs on Expansive Soil Grade Based on ACI 360
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3	1. DESIGN METHODS
4	1,1	DIVIDE AN IRREGULAR FOUNDATION PLAN INTO OVERLAPPING RECTANGLES AND USING
5		THIS SPREADSHEET DESIGN EACH RECTANGULAR SECTION SEPARATELY.
6	1,2	THE POST-TENSION INSTITUTE (PTI) METHOD IS ACCEPTABLE FOR THE DESIGN OF
7		NONPRESTRESSED SLAB ON GRADE (IBC 09 1808.6.2). THE DESIGNER MAY SELECT EITHER
8		NONPRESTRESSED REINFORCEMENT USING THIS SPREADSHEET, OR POST-TENSIONED
9		REINFORCEMENT IF REQUIRED (ACI 360, 9).
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24	2. INPUT DATA & DESIGN SUMMARY
25	2.1 SOILS PROPERTIES
26		ALLOWABLE SOIL-BEARING PRESSURE				qallow	=	2000	psf
27		EDGE MOISTURE VARIATION DISTANCE				em	=	4	ft, for center lift
28							=	4,5	ft, for edge lift
29		DIFFERENTIAL SOIL MOVEMENT				ym	=	2,68	in, for center lift
30							=	0,3	in, for edge lift
31	2.2 STRUCTURAL DATA AND MATERIALS PROPERTIES
32		SLAB LENGTH				L	=	164	ft
33		SLAB WIDTH				B	=	125	ft
34		SLAB THICKNESS				t	=	5	in
35		PERIMETER LOADING				P	=	270	plf
36		MAX BEARING LOADING ON THE SLAB				Pb	=	270	plf
37		ADDED DEAD LOAD				DL	=	50	psf
38		LIVE LOAD				LL	=	125	psf
39		AVERAGE STIFFENING BEAM SPACING, L DIRECTION				SL	=	30	ft
40		AVERAGE STIFFENING BEAM SPACING, B DIRECTION				SB	=	30	ft			THE DESIGN IS ADEQUATE.
41		STIFFENING BEAM DEPTH				h	=	24	in
42		STIFFENING BEAM WIDTH				b	=	20	in
43		CONCRETE STRENGTH				f'c	=	3	ksi
44		REINFORCEMENT IN THE BOTTOM OF STIFFENING BEAM				2	#	6
45		SLAB REINFORCEMENT			#	4	@	18	in o.c., with	1,5	in clear from top of slab, each way.
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47	3. ASSUME A TRIAL SECTION
48	3.1 ASSUME BEAM DEPTH AND SPACING
49		ALLOWABLE DIFFERENTIAL DEFLECTION, FOR CENTER LIFT, AT L DIRECTION							ALLOWABLE DIFFERENTIAL DEFLECTION, FOR CENTER LIFT, AT B DIRECTION
50			Dallow = 12 MIN(L, 6b) / CD =		1,60	in				Dallow = 12 MIN(B, 6b) / CD =		1,60	in
51			Where	b =	8	ft				Where	b =	8	ft
52				CD =	360						CD =	360
53		ALLOWABLE DIFFERENTIAL DEFLECTION, FOR EDGE LIFT, AT L DIRECTION							ALLOWABLE DIFFERENTIAL DEFLECTION, FOR EDGE LIFT, AT B DIRECTION
54			Dallow = 12 MIN(L, 6b) / CD =		0,80	in				Dallow = 12 MIN(B, 6b) / CD =		0,80	in
55			Where	b =	8	ft				Where	b =	8	ft
56				CD =	720						CD =	720
57		BEAM DEPTH, FOR CENTER LIFT, AT L DIRECTION							BEAM DEPTH, FOR CENTER LIFT, AT B DIRECTION
58			h = [(ym L)0.205 SB1.059 P0.523 em1.296 / 380 Dallow ]0.824 =				13,56	in		h = [(ym B)0.205 SL1.059 P0.523 em1.296 / 380 Dallow ]0.824 =				12,95	in
59		BEAM DEPTH, FOR EDGE LIFT, AT L DIRECTION							BEAM DEPTH, FOR EDGE LIFT, AT B DIRECTION
60			h = [L0.35 SB0.88 em0.74 ym0.76 / 15.9 Dallow P0.01]1.176 =				8,47	in		h = [B0.35 SL0.88 em0.74 ym0.76 / 15.9 Dallow P0.01]1.176 =				7,58	in
61				GOVERNING h =	13,56	in	<		ACTUAL h =	24,00	in	[Satisfactory]
62	3.2 DETERMINE SECTION PROPERTIES
63		L DIRECTION							B DIRECTION
64		As =	17	in2	n =	6	beams		As =	22	in2	n =	7	beams
65		Es / Ec =	9,29		yb =	18,75	in		Es / Ec =	9,29		yb =	19,00	in
66		CGS =	21,75	in	St =	64268	in3		CGS =	22,25	in	St =	80834	in3
67		A =	9935	in2	Sb =	17995	in3		A =	12703	in2	Sb =	21276	in3
68		I =	337410	in4					I =	404232	in4
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70	4. CALCULATE MAXIMUM APPLIED SERVICE MOMENTS
71	4.1 CENTER LIFT MOMENT AT L DIRECTION								CENTER LIFT MOMENT AT B DIRECTION
72		ML = A0 (B em1.238 + C) =		4,96	ft-kips / ft					MB = (58 + em) ML / 60, for L /B > 1.1			=	5,12	ft-kips / ft
73		Where	A0 = (L0.013 SB0.306 h0.688 P0.534 ym0.193) / 727 =				0,891			MB = ML, for L /B < 1.1			=	5,12	ft-kips / ft
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75			B = 1, for em < 5			=	1,00
76			B = MIN[(ym - 1) / 3, 1], for em > 5			=	1,00
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78			C = 0, for em < 5				=	0,00
79			C = MAX{[8 - (P - 613) / 255] (4 - ym) / 3], 0}, for em > 5				=	0,00
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81	4.2 EDGE LIFT MOMENT AT L DIRECTION								EDGE LIFT MOMENT AT B DIRECTION
82		ML = SB0.10 (h em)0.78 ym0.66 / (7.2 L0.0065 P0.04) =				2,63	ft-kips / ft					MB = h0.35 (19 + em) ML / 57.75, for L /B > 1.1	=	3,25	ft-kips / ft
83										MB = ML, for L /B < 1.1			=	3,25	ft-kips / ft
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85	5. CHECK FLEXURAL CONCRETE STRESSES
86	5.1 ALLOWABLE CONCRETE STRESSES
87		FLEXURAL TENSILE STRESS			ft,allow = - 6 (fc')0.5 =	-0,329	ksi
88		FLEXURAL COMPRESSIVE STRESS			fc,allow = - 0.45 fc' =	1,350	ksi
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90	5.2 TOP STRESS, FOR CENTER LIFT MOMENT, AT L DIRECTION								TOP STRESS, FOR CENTER LIFT MOMENT, AT B DIRECTION
91		f = - ML / St =	-0,116	ksi						f = - MB / St =	-0,125	ksi
92		Then f	>	ft,allow	[Satisfactory]					Then f	>	ft,allow	[Satisfactory]
93		Then f	<	fc,allow	[Satisfactory]					Then f	<	fc,allow	[Satisfactory]
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95	5.3 BOTTOM STRESS, FOR CENTER LIFT MOMENT, AT L DIRECTION								BOTTOM STRESS, FOR CENTER LIFT MOMENT, AT B DIRECTION
96		f = ML / Sb =	0,413	ksi						f = MB / Sb =	0,474	ksi
97		Then f	>	ft,allow	[Satisfactory]					Then f	>	ft,allow	[Satisfactory]
98		Then f	<	fc,allow	[Satisfactory]					Then f	<	fc,allow	[Satisfactory]
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100	5.4 TOP STRESS, FOR EDGE LIFT MOMENT, AT L DIRECTION								TOP STRESS, FOR EDGE LIFT MOMENT, AT B DIRECTION