HW15 - Answer Key PDF

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Answer key. Problems ~will not~ be the same so just use this as a stepping stone....

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HW – Solution 4.9.2020

ARC434

SoA - UK CoD

1. Design a roof deck spanning between 45’-0” long roof joists that are spaced 4’-0” O.C. For roof Dead Load consider the following items (on top of roof deck and including roof deck): Single-ply, sheet waterproofing membrane 4” of Cellular glass Insulation Roof Metal Deck Roof Live load/snow load = 20 psf For Ceiling Dead Load consider the following items (below the roof deck supported by roof joists) Plaster on tile or concrete Mechanical ducts (includes other MEP items)

Use 1.5” Wide Rib Roof Deck with 3-span continuous to select the deck. Make sure that you satisfy maximum SDI Construction Span as well as the load requirements. For the design of the Joists, find the lightest joist. Note that the self-weight of the joist must be deducted from the total load shown in the table. The joists must satisfy L/360 live load deflection. Solution: Deck Design: 1.5” Wide Rib Roof Deck with 3-span continuous – Deck Span = 4’ – 0” Dead load = 0.7 PSF (membrane) + 4 x 0.7 (4” of Insulation) + (assume 20” gauge) 2.5 PSF = 6 PSF Live Load = 20 PSF, Total Service Load = 6 20 = 26 PSF From VULCRAFT Table: SDI Min. Span = 5’ 10” > 4’ – 0” Span OK, Total Load available 154/120 PSF > 26 PSF OK Assumed deck weight = 2.5PSF < 24 Gauge 1.46 PSF OK 1.5B / 1.5BI / 1.5BA / 1.5BIA ROOF DECK

Use 1.5B -24 Gauge

• Maximum Sheet Length 42’-0” • Extra charge for lengths under 6’-0”

Design Thickness (in.)

• ICC ESR-1227 • FM Global Approved

DIMENSIONS

B22

0.0295

1.78

B20

0.0358

2.14

B19

0.0418

2.49

B18

0.0474

2.82

B16

0.0598

3.54

VERTICAL LOADS FOR TYPE 1.5B No. of Spans

Deck Type

Max. SDI Const. Span

Allowable Total Load (psf) / Load Causing Deflection of L/240 or 1 inch (psf) Span (ft-in.) ctr to ctr of supports 5-0

5-6

6-0

6-6

7-0

7-6

8-0

128 / 90

108 / 69

92 / 55

79 / 44

69 / 35

61 / 29

8-6 54 / 24

9-0 48 / 21

9-6 43 / 17

10-0 39 / 15

74 / 76

64 / 61

56 / 50

49 / 41

43 / 34

39 / 29

35 / 24

31 / 21

B22

6'-11

124 / 167

103 / 126

87 / 97

B20

7'-9

159 / 209

132 / 157

111 / 121

95 / 95

82 / 76

72 / 62

63 / 51

56 / 43

50 / 36

45 / 31

40 / 26

B19

8'-5

186 / 250

154 / 188

130 / 145

111 / 114

96 / 91

84 / 74

74 / 61

65 / 51

58 / 43

52 / 37

47 / 31

B18

9'-1

210 / 289

174 / 217

147 / 167

126 / 132

108 / 105

95 / 86

83 / 71

74 / 59

66 / 50

59 / 42

54 / 36

B16

10'-3

264 / 369

219 / 277

185 / 214

158 / 168

136 / 135

119 / 109

105 / 90

93 / 75

83 / 63

74 / 54

67 / 46

pg. 1

HW – Solution 4.9.2020

ARC434

SoA - UK CoD

Joist Design: Typical Joist Span = 45’ – 0”, Spacing = 4’ – 0” Dead Load above the Joist = 0.7 PSF (membrane) + 4 x 0.7 (4” of Insulation) + (Actual 24 gauge) 1.46 PSF = 5 PSF Dead Load below the Joist (Ceiling) = 5 PSF (Plaster on tile or concrete) + 4 PSF (MEP) = 9 PSF Total Dead Load = 5 + 9 = 14 PSF, Live Load = 20 PSF Load on a Typical Joist: WDL = 14 PSF x 4’ = 56 lbs/ft, w LL = 20 PSF x 4’ = 80 lbs/ft wTL = 56 + 80 = 136 lbs/ft From Vulcraft Table The RED figures in the Load Table represent the uniform load, in pounds per linear foot, which will produce an approximate joist deflection of 1/360 of the span. Where the joist span is in the RED SHADED area of the Load Table, the row of bridging nearest the mid span shall be diagonal bridging with bolted connections at chords and intersections. Hoisting cables shall not be released until this row of bolted diagonal bridging is completely installed. The RED SHADED area extends up through 60’–0”.

24K5 with Total Safe allowable load = 164 lbs/ft > 136 lbs/ft, and L/360 deflection load = 86 lbs/ft > w = 80 lbs/ft

LL

Use Joist 24K5 x 45’ – 0” in Span @ 4’- 0” O.C.

pg. 2

HW – Solution 4.9.2020

ARC434

SoA - UK CoD

2. Design floor deck spanning between 45’-0” long floor joists that are spaced 2’-0” O.C. Dead Load is Self-weight of the floor

0.6C / 0.6CSV CONFORM DECK

Terrazzo (1-1/2-in.) directly on slab Plaster on tile or concrete Mechanical ducts (includes other MEP items)

DIMENSIONS

Use 9/16” Form Deck with 4 ½” normal weight concrete, (t = 4.00”). Live load is 100 psf. For the design of the Joists, find the lightest joist. Note that the self-weight of the joist must be deducted from the total load shown in the table. The joists must satisfy L/360 live load deflection. DIMENSIONS Solution:

0.6C / 0.6CSV CONFORM DECK

Deck Design: T 1 SPAN

2 SPAN

2'-0

2'-4

3

Weight (psf)

N

LW Concrete N=14 110 PCF 2 SPAN

3 SPAN

40

1 SPAN 2'-1

2'-6

2'-7

0.6C26

53

2'-4

2'-9

2'-10

40

2'-6

3'-0

3'-0

0.6C24

53

2'-11

3'-5

3'-6

41

3'-1

3'-8

3'-9

0.6C22

54

3'-4

4'-0

4'-0

41

3'-7

4'-3

4'-4

Fb = 36,000 1

2

210

2- 3

2- 6

2- 9

3- 0

3- 3

3- 6

3- 9

4- 0

4- 6

5- 0

5- 6

6- 0

166

134

111

93

79

68

60

52

41

34

28

23

Defl. = l/240

98

69

50

38

29

23

18

15

12

9

6

5

4

Defl. = l/180

131

92

67

51

39

31

25

20

16

12

8

6

5

Fb = 36,000

210

167

136

112

95

81

70

61

54

42

34

28

24

Defl. = l/240

237

167

121

91

70

55

44

36

30

21

15

11

9

Defl. = l/180

316

Fb = 36,000

222

162

122

94

74

59

48

40

28

20

15

12

207

168

140

118

101

87

76

67

53

43

35

30

Defl. = l/240

186

130

95

71

55

43

35

28

23

16

12

9

7

Defl. = l/180

247

174

127

95

73

58

46

38

31

22

16

12

9

Select 0.6C28( 9/16”) Form Deck with 4 ½” NW Concrete (t = 4.00”) Joist Design: Total Dead Load = 19 PSF (Terrazzo) + 5 PSF (Plaster on tile or concrete) + 53 PSF (0.6C28 Form Deck with 4 ½” NW Concrete) + 4 PSF (MEP) = 81 PSF Dead Load on a typical joist, W DL = 81 PSF x 2 FT = 162 lbs/ft, W LL = 100 PSF x 2FT =200 lbs/ft, w TL = 362 lbs/ft

pg. 3

HW – Solution 4.9.2020

ARC434

Joist 26k12, 13.7 lbs/ft: Allowable total load = 389 – 13.7 (self-weight) = 375.3 lbs/ft > w

SoA - UK CoD

TL =362

lbs/ft OK

Allowable load for L/360 Deflection = 212 lbs/ft > w LL = 200 lbs/ft OK

Joist 30K11, 13.3 lbs/ft: Allowable total load = 389 – 13.7 (self-weight) = 375.3 lbs/ft > w

TL =362

lbs/ft OK

Allowable load for L/360 Deflection = 246 lbs/ft > w LL = 200 lbs/ft OK 30K11 is lighter than 26K12:

Select 30K11

pg. 4...