Steel Bridges Disadvantages/steel Bridge Competition 2013

Load-bearing capacity of Type 321 Bailey Bridge

Type 321 Bailey Bridge is a prefabricated steel bridge widely used in bridge engineering. It has the characteristics of simple structure, convenient transportation, quick erection, large load capacity, good interchangeability and strong adaptability. The following is the specific load-bearing capacity of Type 321 Bailey Bridge:

1. **Design load**
Type 321 Bailey Bridge is suitable for a variety of load levels, as follows:
- **Automobile load**: Applicable to automobile-10 level, automobile-15 level, automobile-20 level.
- **Track load**: Can carry crawler load of 50 tons.
- **Trailer load**: Can carry trailer-80 level.

2. **Specific parameters**
- **Single-piece Bailey beam**:
- Allowable bending moment (MX): 782 kN-m.
- Allowable shear force (QX): 242 kN.
- **Combined bridge**:
- Single-layer single row (SS): allowable bending moment 78.82 T.m, allowable shear force 24.52 T.
- Double-layer double row (DS): allowable bending moment 157.64 T.m, allowable shear force 49.04 T.
- Three-row single layer (TS): allowable bending moment 224.637 T.m, allowable shear force 69.882 T.
- Double-row double layer (DD): allowable bending moment 326.54 T.m, allowable shear force 49.05 T.
- Three-row double layer (TD): allowable bending moment 465.32 T.m, allowable shear force 69.89 T.

3. **Actual application case**
In actual application, the 321 type Bailey bridge can meet the traffic needs of various heavy vehicles. For example, in a certain project, 321-type Bailey bridges were used as the main beams, with a 6-row single-layer top-bearing structure and a designed traffic load of 100 tons.

Summary
The 321-type Bailey bridge can meet the traffic needs of a variety of heavy vehicles with its high load-bearing capacity, flexible design and structural improvements. Its design loads include car-10, car-15, car-20, crawler-50 and trailer-80, making it an ideal choice for various complex engineering needs.

Specifications:

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CB200 Truss Press Limited Table
NO.	Internal Force	Structure Form
		Not Reinforced Model				Reinforced Model
		SS	DS	TS	QS	SSR	DSR	TSR	QSR
200	Standard Truss Moment(kN.m)	1034.3	2027.2	2978.8	3930.3	2165.4	4244.2	6236.4	8228.6
200	Standard Truss Shear (kN)	222.1	435.3	639.6	843.9	222.1	435.3	639.6	843.9
201	High Bending Truss Moment(kN.m)	1593.2	3122.8	4585.5	6054.3	3335.8	6538.2	9607.1	12676.1
202	High Bending Truss Shear(kN)	348	696	1044	1392	348	696	1044	1392
203	Shear Force of Super High Shear Truss(kN)	509.8	999.2	1468.2	1937.2	509.8	999.2	1468.2	1937.2

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CB200 Table of Geometric Characteristics of Truss Bridge(Half Bridge)
Structure	Geometric Characteristics
	Geometric Characteristics	Chord Area(cm2)	Section Properties(cm3)	Moment of Inertia(cm4)
ss	SS	25.48	5437	580174
	SSR	50.96	10875	1160348
DS	DS	50.96	10875	1160348
	DSR1	76.44	16312	1740522
	DSR2	101.92	21750	2320696
TS	TS	76.44	16312	1740522
	TSR2	127.4	27185	2900870
	TSR3	152.88	32625	3481044
QS	QS	101.92	21750	2320696
	QSR3	178.36	38059	4061218
	QSR4	203.84	43500	4641392

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CB321(100) Truss Press Limited Table
No.	Lnternal Force	Structure Form
		Not Reinforced Model				Reinforced Model
		SS	DS	TS	DDR	SSR	DSR	TSR	DDR
321(100)	Standard Truss Moment(kN.m)	788.2	1576.4	2246.4	3265.4	1687.5	3375	4809.4	6750
321(100)	Standard Truss Shear (kN)	245.2	490.5	698.9	490.5	245.2	490.5	698.9	490.5
321 (100) Table of geometric characteristics of truss bridge(Half bridge)
Type No.	Geometric Characteristics	Structure Form
		Not Reinforced Model				Reinforced Model
		SS	DS	TS	DDR	SSR	DSR	TSR	DDR
321(100)	Section properties(cm3)	3578.5	7157.1	10735.6	14817.9	7699.1	15398.3	23097.4	30641.7
321(100)	Moment of inertia(cm4)	250497.2	500994.4	751491.6	2148588.8	577434.4	1154868.8	1732303.2	4596255.2

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Advantage

Possessing the features of simple structure,
convenient transport, speedy erection
easy disassembling,
heavy loading capacity,
great stability and long fatigue life
being capable of an alternative span, loading capacity