Stresses in Bascule Trusses

Taken from blueprints supplied by the Florida East Coast Railway Company. My thanks to them for their generous cooperation. These figures are for the instruction of fine-scale modelers. Stresses are given in 1000 #.


Main trusses

Pluses indicate compression; minuses indicate tension. Values with an "x" prefix (printed in red) indicate maximum dead load with the bridge moving. Values with an asterisk (cyan) indicate maximum dead load plus 20% of impact load. Values with an "o" (blue) indicate wind plus traction.


			Live Load	Impact Load	Total Load					Unit Stress
Member	Dead Load	+	-	+	-	+	-		Wind	Traction	+	-
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0-1	-55.0		655.0		269.0		897.0						12.25
1-3	-121.0		626.0		261.0		827.0						12.5
3-5	-270.0		761.0		351.0		977.0						12.5
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5-9	-481.0		778.0		381.0		919.0	721.0					12.5
9-11	-752.0		737.0		326.0		466.0	907.0					12.5	16.0
11-13	-313.0		709.0		284.0		837.0	*935.0					12.5	16.0
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13-15	-135.0		734.0		298.0		965.0	*720.0					12.5
0-4	+31.0			375.0		154.0		o710.0		-124.0	+-72.0			20.0
4-6	121.0			626.0		261.0		o1110.0		-193.0	+-90.0			20.0
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6-8	x350.0			762.0		351.0		o1304.0		-218.0	+-108.0			20.0
	270.0
8-10	x790.0			737.0		326.0	*948.0			+203.0	+-126.0		12.5
	752.0
10-12	x1137.0			564.0		226.0	*1360.0			+186.0	+-144.0		12.5
	1092.0

			Live Load	Impact Load	Total Load					Unit Stress
Member	Dead Load	+	-	+	-	+	-		Wind	Traction	+	-
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12-14	x1000.0			596.0		242.0	*1200.0			+136.0	+-158.0		12.5
	960.0
14-15	x1040.0		37.0	577.0	36.0	248.0	*1250.0			+74.0	+-172.0		12.5
	995.0		39.0
14-16	-23.0			232.0		226.0		481.0						16.0
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1-4	158.0		23.0	494.0	22.0	237.0	305.0	675.0						16.0
3-6	260.0		70.0	353.0	59.0	200.0	536.0	440.0					11.5
5-8	368.0		158.0	233.0	110.0	159.0	657.0						11.5
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8-9	-472.0		131.0	265.0	102.0	173.0		910.0						16.0
10-11	-593.0			394.0		213.0		1200.0						16.0
12-13	217.0		125.0		120.0		462.0						12.3
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3-4	184.0		285.0	57.0	161.0	48.0	393.0	420.0					12.3	16.0
5-6	270.0		188.0	128.0	128.0	96.0		517.0						16.0	
9-10	413.0		214.0	106.0	139.0	83.0	766.0						12.3
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1-2	-51.0			220.0		200.0		471.0						16.0
11-12	-217.0			241.0		213.0		671.0						16.0
13-14	-245.0			150.0		144.0		529.0						16.0
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7-8	+19.0						19.0

Flooring

Dead, live, impact and total loads on the floors.

Member				Shears in 1000 #		Moments in 1000 ft. lbs.
				D.L.	L.L.	Imp.	Total	D.L.	L.L.	Imp.	Total
----------------------------------------------------------------------------------------------
Stringer span 28'		8.0	92.6	90.2	190.8	56.0	575.0	560.0	1191.0
Stringer span 21'6"		5.0	77.0	76.0	158.0	27.0	342.0	337.0	706.0
Floor beam at 0			28.0	257.0	176.8	461.8	270.0	2486.0	1710.0	4466.0
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Floor beam at 2,4,6,8,10,12	34.2	220.0	200.0	454.2	330.0	2128.0	1934.0	4392.0
Floor beam at 14		28.0	190.4	179.4	397.8	270.0	1840.0	1740.0	3850.0
Floor beam at 16		24.0	231.6	154.0	409.6	232.0	2240.0	1490.0	3962.0