Floors. Part 3

Description

This section is from the "Architectural Iron And Steel, And Its Application In The Construction Of Buildings" book, by WM. H. Birkmire.. Also see Amazon: Architectural Iron And Steel, And Its Application In The Construction Of Buildings.

Floors. Part 3

44. Bearing For Beams

When the ends of beams rest upon walls, cast or wrought iron bed plates should be used to distribute the pressure over a greater surface. For buildings stone beds are generally used, but when the pressure is great both plates and stone. Beams have seldom less than 8 inches bearing or more than 12 inches; if less than 8 feet long, 6 inches will be sufficient.

45. Pressure On Brick And Stone Work

The pressure per square foot for brickwork should not exceed six tons, and for stone twelve to twenty tons, according to its character.

46. Knees For Beam Connections

The following sizes of knees are commonly used for beam connections:

24" into	24" beam =	6 X 4 X 1/2"	angles, 20"	long;
20" "	20" " =	6 X 4 X 1/2"	" 16"	"
15" "	15" " =	6X4X1/2"	" 11"	"
12" "	12" " =	6 X 4 X 1/2	" 8"	"
10 1/2" "	10 1/2" " =	6 X 4 X 7/16"	" 6 1/2"	"

10" into	10" beam	= 6 X 4 X 7/16"	angles, 6"	long;
9" "	9" "	= 6X4X7/16"	" 5"
8" "	8" "	= 5 X 3 1/2 X 3/8"	" 4 1/2"	"
7" "	7" "	= 5 X 3 1/2 X 3/8"	" 3 1/2"	"
6" "	6" "	= 5 X 3 1/2 X 3/8"	" 3"	"
5" "	5" "	= 5 X 3 1/2 X 3/8"	" 2 1/2"	"
4" "	4" "	= 3 1/2 X 3 1/2 X 3/8"	" 2 1/4"	"

47. Bolts And Rivets For Beam Connections

The number of bolts and rivets is determined by shearing and bearing strain. See article on "Bolts and Rivets".

48. Tee Irons As Beams

The following table gives:

Safe Load, In Pounds, Uniformly Distributed, For Tirons, Including Weight Of T

Maximum Strain 12,000 Pounds per Square Inch.

Size of T.			Weight per yard.	Coefficient for Transverse Strain.	Distance between Supports, in feet.
Size of T.			Weight per yard.	Coefficient for Transverse Strain.	4	5	6	7	8	9	I0	11	12
flange	stem	th'kness	lbs.
5	X3"	X1/2"	38.1	7480	1870	1500	1250	1070	940	830	750	680	620
4 1/2	X3 1/2	x11/16	46.5	6010	1502	I200	IOOO	860	750	670	600	550	500
4	X5	X 1/2	45.6	24,800	6200	4960	4130	3540	3I00	,2770	2480	2250	2070
4	X4 1/2	X1/2	42.9	20,400	5100	4080	3400	2910	2550	2270	2040	1860	1700
4	X4	X1/2	37.5	I5,800	3950	3l60	2633	2257	1975	1755	1580	1435	1325
4	X3	XI	27.3	7070	1705	1414	1178	IOIO	884	785	707	634	589
3 1/2	X3 1/2	x1/2	27.O	9530	2382	1900	1590	1360	II90	IO60	950	870	790
3 1/2	X4	X3/8	29.1	12,380	3095	2476	2064	1770	I550	1380	1240	1130	1030
3 1/2	X3	x1/2	22.5	5790	1418	1l60	970	830	720	640	580	530	480
3	X4	x1/2	34.8	15,480	387O	3I00	2580	2210	1940	1720	I550	1410	1290
3	X3 1/2	x1/2	32.1	11,910	2975	2380	1990	1700	1490	1320	1190	1080	990
3	X3	x 5/16	19.5	5900	1475	Il80	980	840	740	650	590	540	490
3	X 2 1/2	X5/16	18.0	4100	I025	820	680	590	5IO	460	410	370	340
3	X 2	x 5/16	14.6	2540	637	508	423	363	317	283	254	231	212
2 1/2	X2 1/2	x 5/16	16.2	4000	I000	800	670	570	500	440	400	360	330
2 1/2	X3	x5/16	18.0	6110	1527	I220	1020	870	760	680	610	560	510
2 1/4	X 2 1/2	X9/32	11.90	2811	703	560	469	402	352	312	281	254	234
2	X 2	x1/4	9.4	I970	493	394	328	282	246	218	197	179	164
1 3/4	X 1 3/4	x1/4	9.0	1550	39°	310	260	220	190	170	155	140	130
1 1/2	X 1 1/2	x1/4	6.68	1033	258	207	172	147	129	115	103	94	86
I 1/4	XI 1/4	x7/32	4.87	596	149	119	98	85	75	66	59	54	49
I	X I	x5/32	2.80	268	67	53	45	38	36	29	26	24	22

49. Angle Irons As Beams

The following table gives:

Safe Load, In Pounds, Uniformly Distributed, For Equal-Leg Angles, Including Weight Of Angles

Maximum Strain 12,000 Pounds per Square Inch.

Size of Angle.	Weight yard.	Coefficient for Transverse Strength.	Distance between Supports, in feet.
Size of Angle.	Weight yard.	Coefficient for Transverse Strength.	4	5	6	7	8	9	10	XX	12
inches.	lbs.
6 X6 X7/16	50.6	32,560	8140	6510	5430	4650	4070	3620	3260	2960	2715
6 X6 X1/2	57.5	36,900	9225	7400	6150	5270	4612	4100	3690	3354	3075
5X5X 3/5	36.0	19,360	4840	3870	3230	2770	2420	2150	1940	1760	1618
4 1/2 X 4 1/2 X A	37.5	18,000	4500	3600	3000	2571	2250	2000	1800	1633	1500
4 X4 XI	28.6	12,184	3046	2437	2031	1740	1523	1354	1218	1107	1015
3 1/2 X 3 1/2 X 3/8	24.8	9200	2300	1840	1530	1310	1150	I020	920	840	770
3 X3 X 1/4	14.4	4611	"53	922	767	658	576	512	461	419	384
2 5/4 X 2 3/4 X 5/16	16.2	4710	1177	942	785	672	589	522	471	428	393
2 1/2 X 2 1/2 X 1/4	11.9	3156	789	631	526	45T	394	344	317	287	263
2 1/4 X 2 1/4 X 1/4	10.6	2530	633	506	422	362	316	281	253	230	211
2 X 2 x 7/32	8.3	1752	438	350	292	250	219	195	175	159	146
1 3/4 x 1 3/4 x 3/16	6.21	II50	287	230	I92	164	144	128	"5	104	96
1 1/2 x 1 1/2 x 3/16	5.27	832	208	164	139	119	104	92	83	76	69
1 1/4 X 1 1/4 X 1/8	2.97	393	98	78	65	56	49	44	39	36	33

50. Safe Load For Unequal-Leg Angles, The Longer Leg Vertical

Maximum Strain 12,000 Pounds per Square Inch.

Size of Angle.	Weight per yard.	Coefficient for Transverse Strength.	Distance between Supports, in feet.
Size of Angle.	Weight per yard.	Coefficient for Transverse Strength.	4	5	6	7	8	9	10	11	12
inches.	lbs.
6 X4 X 7/16	41.8	30,680	7670	6136	5113	4383	3834	3409	3068	2789	2556
6 X4 X3/8	36.1	26,560	6640	53IO	4430	3790	3320	2950	2660	2410	22I0
6 X 3 1/2 X 3/8	34.2	26,000	6500	5200	4330	3710	3250	2890	2600	2360	2I70
5 X4 X3/8	32.3	18,720	4680	3740	3I20	2670	2340	2080	1870	1700	I560
5 X3 1/2X 3/8	30.5	18,353	4590	3671	3059	2622	2294	2038	1835	1668	1528
5 X3 X 3/8	28.6	17,840	4460	3570	2970	2550	2230	1980	1784	1620	I490
4 1/2X3 X3/8	26.7	14,580	3645	2916	2430	2083	1823	1620	1458	1325	I217
4 X3 1/2X 3/8	26.7	I2,000	3000	2400	2000	1710	1500	I330	I200	I090	1000
4 X3 X5/16	20.9	9850	2462	1970	1641	1407	1231	I094	985	895	821
3 1/2X3 X5/16	19.3	7680	1920	I540	1280	1100	960	850	770	700	640
3 1/2 X 2 1/2 X 1/4	14.4	6000	I500	I200	10000	860	750	670	600	540	500
3 X 2 1/2 X 1/4	I3.I	4480	1120	900	750	640	560	500	450	410	370
3 X2 X1/4	II.9	4320	1080	860	720	620	540	480	430	390	360
2 1/2X2 x3/16	8.1	2320	580	460	390	330	290	260	230	210	190

51. Beams Not Uniformly Loaded And Beams Not Supported At Both Ends

(a) For a beam fixed at one end and loaded at the other as a cantilever, coefficient/8L. Safe load in lbs. =

(6) For a beam fixed at one end and uniformly loaded, coefficient/4L Safe load in lbs. =

Safe load in lbs. =(coefficient/L)x (L2/(8AxB)

A = distance from load to one support; B = distance from load to the other support.

Note. - The beams, channels and other shapes treated of in this chapter are selezcted from the hand-books of the Passaic Rolling Mill Co., Phoenix Iron Co., Columbia Iron and Steel Co., and Pottsville Iron and Steel Co.

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