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SOLUTION MANUAL © 2012 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 1–1....

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SOLUTION MANUAL

© 2012 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher.

1–1. The floor of a heavy storage warehouse building is made of 6-in.-thick stone concrete. If the floor is a slab having a length of 15 ft and width of 10 ft, determine the resultant force caused by the dead load and the live load. From Table 1–3 DL = [12 lb兾ft2 # in.(6 in.)] (15 ft)(10 ft) = 10,800 lb From Table 1–4 LL = (250 lb兾ft2)(15 ft)(10 ft) = 37,500 lb Total Load F = 48,300 lb = 48.3 k

Ans.

1–2. The floor of the office building is made of 4-in.-thick lightweight concrete. If the office floor is a slab having a length of 20 ft and width of 15 ft, determine the resultant force caused by the dead load and the live load. From Table 1–3 DL = [8 lb兾ft2 # in. (4 in.)] (20 ft)(15 ft) = 9600 lb From Table 1–4 LL = (50 lb兾ft2)(20 ft)(15 ft) = 15,000 lb Total Load F = 24,600 lb = 24.6 k

Ans.

1–3. The T-beam is made from concrete having a specific weight of 150 lb兾ft3. Determine the dead load per foot length of beam. Neglect the weight of the steel reinforcement.

40 in.

8 in.

w = (150 lb兾ft3) [(40 in.)(8 in.) + (18 in.) (10 in.)] a

1 ft2 b 144 in2

26 in.

w = 521 lb兾ft

Ans.

10 in.

1

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*1–4. The “New Jersey” barrier is commonly used during highway construction. Determine its weight per foot of length if it is made from plain stone concrete.

4 in.

1 1 Cross-sectional area = 6(24) + a b (24 + 7.1950)(12) + a b (4 + 7.1950)(5.9620) 2 2

75° 12 in. 55°

= 364.54 in2

6 in.

Use Table 1–2. w = 144 lb兾ft3 (364.54 in2) a

1 ft2 b = 365 lb兾ft 144 in2

Ans.

1–5. The floor of a light storage warehouse is made of 150-mm-thick lightweight plain concrete. If the floor is a slab having a length of 7 m and width of 3 m, determine the resultant force caused by the dead load and the live load. From Table 1–3 DL = [0.015 kN兾m2 # mm (150 mm)] (7 m) (3 m) = 47.25 kN From Table 1–4 LL = (6.00 kN兾m2) (7 m) (3 m) = 126 kN Total Load F = 126 kN + 47.25 kN = 173 kN

Ans.

2

24 in.

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1–6. The prestressed concrete girder is made from plain stone concrete and four 34 -in. cold form steel reinforcing rods. Determine the dead weight of the girder per foot of its length.

8 in. 6 in.

1 3 2 Area of concrete = 48(6) + 4 c (14 + 8)(4) d - 4(␲) a b = 462.23 in2 2 8 3 2 Area of steel = 4(␲) a b = 1.767 in2 8 From Table 1–2, 1 ft2 1 ft2 w = (144 lb兾ft3)(462.23 in2) a b + 492 lb兾ft3(1.767 in2) a b 2 144 in 144 in2 = 468 lb兾ft

20 in. 6 in. 8 in. 4 in. 6 in. 4 in.

Ans.

1–7. The wall is 2.5 m high and consists of 51 mm ⫻ 102 mm studs plastered on one side. On the other side is 13 mm fiberboard, and 102 mm clay brick. Determine the average load in kN兾m of length of wall that the wall exerts on the floor. 2.5 m

Use Table 1–3. For studs Weight = 0.57 kN兾m2 (2.5 m) = 1.425 kN兾m For fiberboard Weight = 0.04 kN兾m2 (2.5 m) = 0.1 kN兾m For clay brick Weight = 1.87 kN兾m2 (2.5 m) = 4.675 kN兾m Total weight = 6.20 kN兾m

Ans.

3

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*1–8. A building wall consists of exterior stud walls with brick veneer and 13 mm fiberboard on one side. If the wall is 4 m high, determine the load in kN兾m that it exerts on the floor.

For stud wall with brick veneer. w = (2.30 kN兾m2)(4 m) = 9.20 kN兾m For Fiber board w = (0.04 kN兾m2)(4 m) = 0.16 kN兾m Total weight = 9.2 + 0.16 = 9.36 kN兾m

Ans.

1–9. The interior wall of a building is made from 2 ⫻ 4 wood studs, plastered on two sides. If the wall is 12 ft high, determine the load in lb兾ft of length of wall that it exerts on the floor.

From Table 1–3 w = (20 lb兾ft2)(12 ft) = 240 lb兾ft

Ans.

1–10. The second floor of a light manufacturing building is constructed from a 5-in.-thick stone concrete slab with an added 4-in. cinder concrete fill as shown. If the suspended ceiling of the first floor consists of metal lath and gypsum plaster, determine the dead load for design in pounds per square foot of floor area.

4 in. cinder fill 5 in. concrete slab

ceiling

From Table 1–3, 5-in. concrete slab

= (12)(5)

= 60.0

4-in. cinder fill

= (9)(4)

= 36.0

metal lath & plaster

= 10.0

Total dead load

= 106.0 lb兾ft2

Ans.

4

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1–11. A four-story office building has interior columns spaced 30 ft apart in two perpendicular directions. If the flat-roof live loading is estimated to be 30 lb兾ft2, determine the reduced live load supported by a typical interior column located at ground level.

Floor load: Lo = 50 psf At = (30)(30) = 900 ft2 7 400 ft2

( (

L = Lo 0.25 + L = 50 0.25 + % reduction =

15 2KLLAT 15 24(900)

)

) = 25 psf

25 = 50% 7 40% (OK) 50

Fs = 3[(25 psf)(30 ft)(30 ft)] + 30 psf(30 ft)(30 ft) = 94.5 k

Ans.

*1–12. A two-story light storage warehouse has interior columns that are spaced 12 ft apart in two perpendicular directions. If the live loading on the roof is estimated to be 25 lb兾ft2, determine the reduced live load supported by a typical interior column at (a) the ground-floor level, and (b) the second-floor level.

At = (12)(12) = 144 ft2 FR = (25)(144) = 3600 lb = 3.6 k Since At = 4(144) ft2 7 400 ft2

(

L = 12.5 0.25 +

15 2(4)(144)

)

= 109.375 lb兾ft2

(a) For ground floor column L = 109 psf 7 0.5 Lo = 62.5 psf OK FF = (109.375)(144) = 15.75 k F = FF + FR = 15.75 k + 3.6 k = 19.4 k

Ans.

(b) For second floor column F = FR = 3.60 k

Ans.

5

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1–13. The office building has interior columns spaced 5 m apart in perpendicular directions. Determine the reduced live load supported by a typical interior column located on the first floor under the offices.

From Table 1–4 Lo = 2.40 kN兾m2 AT = (5 m)(5 m) = 25 m2 KLL = 4

(

L = Lo 0.25 +

4.57

) )

2KLLAT

(

4.57

L = 2.40 0.25 +

24(25)

L = 1.70 kN兾m2

Ans.

1.70 kN兾m2 7 0.4 Lo = 0.96 kN兾m2 OK

1–14. A two-story hotel has interior columns for the rooms that are spaced 6 m apart in two perpendicular directions. Determine the reduced live load supported by a typical interior column on the first floor under the public rooms. Table 1–4 Lo = 4.79 kN兾m2 AT = (6 m)(6 m) = 36 m2 KLL = 4

(

L = Lo 0.25 +

4.57

(

L = 4.79 0.25 + L = 3.02

) )

2KLL AT 4.57 24(36)

kN兾m2

Ans.

3.02 kN兾m2 7 0.4 Lo = 1.916 kN兾m2 OK

6

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1–15. Wind blows on the side of a fully enclosed hospital located on open flat terrain in Arizona. Determine the external pressure acting over the windward wall, which has a height of 30 ft. The roof is flat. V = 120 mi兾h Kzt = 1.0 Kd = 1.0 qz = 0.00256 KzKztKdV2 = 0.00256 Kz (1.0)(1.0)(120)2 = 36.86 Kz From Table 1–5, z

Kz

qz

0–15

0.85

31.33

20

0.90

33.18

25

0.94

34.65

30

0.98

36.13

Thus, p = q G Cp – qh (G Cp ) i

= q (0.85)(0.8) - 36.13 (; 0.18) = 0.68q < 6.503 p0–15 = 0.68(31.33) < 6.503 = 14.8 psf or 27.8 psf

Ans.

p20 = 0.68(33.18) < 6.503 = 16.1 psf or 29.1 psf

Ans.

p25 = 0.68(34.65) < 6.503 = 17.1 psf or 30.1 psf

Ans.

p30 = 0.68(36.13) < 6.503 = 18.1 psf or 31.1 psf

Ans.

*1–16. Wind blows on the side of the fully enclosed hospital located on open flat terrain in Arizona. Determine the external pressure acting on the leeward wall, which has a length of 200 ft and a height of 30 ft.

V = 120 mi兾h Kzt = 1.0 Kd = 1.0 qh = 0.00256 KzKztKdV2 = 0.00256 Kz(1.0)(1.0)(120)2 = 36.86 Kz

7

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1–16. Continued

From Table 1–5, for z = h = 30 ft, Kz = 0.98 qh = 36.86(0.98) = 36.13 From the text Lo 200 = = 1 so that Cp = - 0.5 B 200 p = q GCp - qh(GCp ) 2

p = 36.13(0.85)(-0.5) - 36.13(; 0.18) p = - 21.9 psf or - 8.85 psf

Ans.

1–17. A closed storage building is located on open flat terrain in central Ohio. If the side wall of the building is 20 ft high, determine the external wind pressure acting on the windward and leeward walls. Each wall is 60 ft long. Assume the roof is essentially flat.

V = 105 mi兾h Kzt = 1.0 Kd = 1.0 q = 0.00256 KzKztKdV2 = 0.00256 Kz(1.0)(1.0) (105)2 = 28.22 Kz From Table 1–5 z

Kz

qz

0–15

0.85

23.99

20

0.90

25.40

Thus, for windward wall p = qGCp – qh(GCp ) i

= q(0.85)(0.8) – 25.40(; 0.18) = 0.68 q < 4.572 p0 – 15 = 0.68 (23.99) < 4.572 = 11.7 psf or 20.9 psf

Ans.

p20

Ans.

= 0.68 (25.40) < 4.572 = 12.7 psf or 21.8 psf

Leeward wall 60 L = = 1 so that Cp = - 0.5 B 60 p = q GCp - qh(GCp ) i

p = 25.40(0.85)(-0.5) - 25.40 (; 0.18) p = -15.4 psf or -6.22 psf

Ans. 8

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1–18. The light metal storage building is on open flat terrain in central Oklahoma. If the side wall of the building is 14 ft high, what are the two values of the external wind pressure acting on this wall when the wind blows on the back of the building? The roof is essentially flat and the building is fully enclosed. V = 105 mi兾h Kzt = 1.0 Kd = 1.0 qz = 0.00256 KzKztKdV2 = 0.00256 Kz (1.0)(1.0)(105)2 = 28.22 Kz From Table 1–5 For 0 … z … 15 ftKz = 0.85 Thus, qz = 28.22(0.85) = 23.99 p = q GCp - qh(GCp ) i

p = (23.99)(0.85)(0.7) - (23.99)( ; 0.18) p = -9.96 psf or p = -18.6 psf

Ans.

1–19. Determine the resultant force acting perpendicular to the face of the billboard and through its center if it is located in Michigan on open flat terrain. The sign is rigid and has a width of 12 m and a height of 3 m. Its top side is 15 m from the ground. qh = 0.613 KzKztKdV2 Since z = h = 15 m Kz = 1.09 Kzt = 1.0 Kd = 1.0 V = 47 m兾s qh = 0.613(1.09)(1.0)(1.0)(47)2 = 1476.0 N兾m2 B兾s =

3 12 m = 4, s兾h = = 0.2 3m 15

From Table 1–6 Cf = 1.80 F = qh GCf As = (1476.0)(0.85)(1.80)(12)(3) = 81.3 kN

Ans.

9

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*1–20. A hospital located in central Illinois has a flat roof. Determine the snow load in kN兾m2 that is required to design the roof. pf = 0.7 CcCtIs p g pf = 0.7(0.8)(1.0)(1.20)(0.96) = 0.6451 kN兾m2 Also pf = Is p g = (1.20)(0.96) = 1.152 kN兾m2 use pf = 1.15 kN兾m2

Ans.

1–21. The school building has a flat roof. It is located in an open area where the ground snow load is 0.68 kN兾m2. Determine the snow load that is required to design the roof.

pf = 0.7 CcCtIs p g pf = 0.7(0.8)(1.0)(1.20)(0.68) = 0.457 kN兾m2 Also pf = pf = Is p g = (1.20)(0.68) = 0.816 kN兾m2 use pf = 0.816 kN兾m2

Ans.

1–22. The hospital is located in an open area and has a flat roof and the ground snow load is 30 lb兾ft2. Determine the design snow load for the roof.

Since pq = 30 lb兾ft2 7 20 lb兾ft2 then pf = Is pg = 1.20(30) = 36 lb兾ft2

Ans.

10

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2–1. The steel framework is used to support the reinforced stone concrete slab that is used for an office. The slab is 200 mm thick. Sketch the loading that acts along members BE and FED. Take a = 2 m, b = 5 m. Hint: See Tables 1–2 and 1–4.

C B

D

A a

E b F

Beam BE. Since

b 5m = 2.5, the concrete slab will behave as a one way slab. = a 2m

Thus, the tributary area for this beam is rectangular shown in Fig. a and the intensity of the uniform distributed load is 200 mm thick reinforced stone concrete slab: (23.6 kN>m3)(0.2 m)(2 m) = 9.44 kN>m Live load for office: (2.40 kN>m2)(2 m) =

480 kN>m 14.24 kN>m

Ans.

Due to symmetry the vertical reaction at B and E are By = Ey = (14.24 kN>m)(5)>2 = 35.6 kN The loading diagram for beam BE is shown in Fig. b. Beam FED. The only load this beam supports is the vertical reaction of beam BE at E which is Ey = 35.6 kN. The loading diagram for this beam is shown in Fig. c.

11

a

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2–2.

Solve Prob. 2–1 with a = 3 m, b = 4 m.

C B

D

A a

E b F

4 b = 6 2, the concrete slab will behave as a two way slab. Thus, a 3 the tributary area for this beam is the hexagonal area shown in Fig. a and the maximum intensity of the distributed load is

Beam BE.

Since

200 mm thick reinforced stone concrete slab: (23.6 kN>m3)(0.2 m)(3 m) = 14.16 kN>m Live load for office: (2.40 kN>m2)(3 m)

=

720 kN>m 21.36 kN>m

Ans.

Due to symmetry, the vertical reactions at B and E are 1 2 c (21.36 kN>m)(1.5 m) d + (21.36 kN>m)(1 m) 2 By = Ey = 2 = 26.70 kN The loading diagram for Beam BE is shown in Fig. b. Beam FED. The loadings that are supported by this beam are the vertical reaction of beam BE at E which is Ey = 26.70 kN and the triangular distributed load of which its tributary area is the triangular area shown in Fig. a. Its maximum intensity is 200 mm thick reinforced stone concrete slab: (23.6 kN>m3)(0.2 m)(1.5 m) = 7.08 kN>m Live load for office: (2.40 kN>m2)(1.5 m)

=

3.60 kN>m 10.68 kN>m

Ans.

The loading diagram for Beam FED is shown in Fig. c.

12

a

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2–3. The floor system used in a school classroom consists of a 4-in. reinforced stone concrete slab. Sketch the loading that acts along the joist BF and side girder ABCDE. Set a = 10 ft, b = 30 ft. Hint: See Tables 1–2 and 1–4.

E a a a

B

30 ft b = 3, the concrete slab will behave as a one way slab. = a 10 ft Thus, the tributary area for this joist is the rectangular area shown in Fig. a and the Since

intensity of the uniform distributed load is 4 in thick reinforced stone concrete slab: (0.15 k>ft3) a Live load for classroom: (0.04 k>ft2)(10 ft) =

4 ftb (10 ft) = 0.5 k>ft 12

0.4 k>ft 0.9 k>ft

Ans.

Due to symmetry, the vertical reactions at B and F are By = Fy = (0.9 k>ft)(30 ft)>2 = 13.5 k

Ans.

The loading diagram for joist BF is shown in Fig. b. Girder ABCDE. The loads that act on this girder are the vertical reactions of the joists at B, C, and D, which are By = Cy = Dy = 13.5 k. The loading diagram for this girder is shown in Fig. c.

13

D C

A

Joist BF.

b

a

F

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*2–4.

Solve Prob. 2–3 with a = 10 ft, b = 15 ft. E

b

a a a a

C B

A

15 ft b = = 1.5 < 2, the concrete slab will behave as a two way a 10 ft slab. Thus, the tributary area for the joist is the hexagonal area as shown Joist BF.

Since

in Fig. a and the maximum intensity of the distributed load is 4 in thick reinforced stone concrete slab: (0.15 k>ft3) a Live load for classroom: (0.04 k>ft2)(10 ft)

4 ft b (10 ft) = 0.5 k>ft 12 0.4 k>ft = Ans. 0.9 k>ft

Due to symmetry, the vertical reactions at B and G are

1 2 c (0.9 k>ft)(5 ft) d + (0.9 k>ft)(5 ft)...