The floor beam in Fig. 1–8 is used to support the 6-ft width of a lightweight plain concrete slab having a thickness of 4 in. The slab serves as a portion of the ceiling for the floor below, and therefore its bottom is coated with plaster. Furthermore, an 8-ft-high, 12-in.-thick lightweight solid

Question

The floor beam in Fig. 1–8 is used to support the 6-ft width of a lightweight plain concrete slab having a thickness of 4 in. The slab serves as a portion of the ceiling for the floor below, and therefore its bottom is coated with plaster. Furthermore, an 8-ft-high, 12-in.-thick lightweight solid concrete block wall is directly over the top flange of the beam. Determine the loading on the beam measured per foot of length of the beam.

Accepted Answer

Using the data in Tables 1–2 and 1–3, we have

TABLE 1-2 Minimum Densities for Design Loads from Materials
	[latex]{lb}/{ft^{3} }[/latex]	[latex]{kN}/{m^{3}}[/latex]
Aluminum	170	26.7
Concrete, plain cinder	108	17.0
Concrete, plain stone	144	22.6
Concrete, reinforced cinder	111	17.4
Concrete, reinforced stone	150	23.6
Clay, dry	63	9.9
Clay, damp	110	17.3
Sand and gravel, dry, loose	100	15.7
Sand and gravel, wet	120	18.9
Masonry, lightweight solid concrete	105	16.5
Masonry, normal weight	135	21.2
Plywood	36	5.7
Steel, cold-drawn	492	77.3
Wood, Douglas Fir	34	5.3
Wood, Southern Pine	37	5.8
Wood, spruce	29	4.5

TABLE 1-3 Minimum Design Dead Loads
*Walls*	psf	[latex]{kN}/{m^{2}}[/latex]
4-in. (102 mm) clay brick	39	1.87
8-in. (203 mm) clay brick	79	3.78
12-in. (305 mm) clay brick	115	5.51
*Frame Partitions and Walls*
Exterior stud walls with brick veneer	48	2.30
Windows, glass, frame and sash	8	0.38
Wood studs [latex]2 imes 4in.[/latex],[latex]\left(51 imes 102 mm ight)[/latex] unplastered	4	0.19
Wood studs [latex]2 imes 4in.[/latex],[latex]\left(51 imes 102 mm ight) [/latex]plastered one side	12	0.57
Wood studs [latex]2 imes 4in.[/latex],[latex]\left(51 imes 102 mm ight) [/latex]plastered two sides	20	0.96
*Floor Fill*
Cinder concrete, per inch (mm)	9	0.017
Lightweight concrete, plain, per inch (mm)	8	0.015
Stone concrete, per inch (mm)	12	0.023
*Ceilings*
Acoustical fiberboard	1	0.05
Plaster on tile or concrete	5	0.24
Suspended metal lath and gypsum plaster	10	0.48
Asphalt shingles	2	0.1
Fiberboard,[latex]\frac{1}{2} in.[/latex] (13 mm)	0.75	0.04

Concrete slab: [latex] \left[{8 lb}/{\left(ft^{2}\cdot in. ight) } ight] \left(4 in. ight) \left(6 ft ight) =192{lb}/{ft}[/latex]

Plaster ceiling: [latex]\left(5{lb}/{ft^{2} } ight) \left(6 ft ight)=30 {lb}/{ft} [/latex]

Block wall:[latex]\left(105{lb}/{ft^{3} } ight) \left(8 ft ight)\left(1 ft ight)={840 {lb}/{ft}} [/latex]

Total load: [latex] {1062 {lb}/{ft}} =1.06 { {k}/{ft}}[/latex]

Here the unit k stands for “kip,” which symbolizes kilopounds. Hence, [latex] 1 k= 1000 lb.[/latex]

Question 1.1: The floor beam in Fig. 1–8 is used to support the 6-ft width...

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