Suspension Bridge

Construction

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A suspension bridge is such bridge which is hinged with the help of ropes either made of heavy steel or tungsten containing alloys of steel.  The suspension bridge does not require any support in the middle and can bear a huge load. The important features of this bridge is that it cannot get affected by earthquake and  any other natural calamities .They start floating if by default any natural calamity takes place .

Suspension bridges make uses of box section roadway supported by high tensile strength cables. The cables are made of thousands of individuals steel wires bound tightly together. steel ,which is made are must have to very strong under tension , is an ideal material for cables ; a single steel wire, only 0.1 inch thick, can support over half a ton (Design Technology, n .d.).

Suspension bridges tend to very expensive to build. a suspension bridge suspends the roadways from various cables. These cables rest on the top of high towers and have to be securely anchored into the bank at either end of the bridge. These towers enable the main cables to be draped over long distance.

Most of the weight or load of the bridge is transferred by the cables to the anchorage system. These are imbedded in either solid rock and in the anchorage system, the cables are spread over the large area.

Suspension bridges in the historical times were made of rope and wood. Modern suspension bridges use a box section roadway supported by high tensile strength cables in the early nineteenth century, suspension bridges used iron chains for cables. The high tensile cables used in modern suspension bridges were introduced in the nineteenth century ( ref-design technology)

The material required for making the suspension bridge

1. A hard card board
2. Tapes
3. Different toothpicks
4. Pieces of wood
5. 2 water bottles

Various suspension bridges all over the world

1. Capilano suspension bridge
2. Clifton suspension bridge
3. Akashi kaikyo
4. John A.roelbling
5. Goldengate
6. Tacorna narrow
7. Menai suspension

First of all we take a cardboard and make two dome having   house on the two side (length of the domed house is 13 cm )  and kept at a distance of 85 cm ; two wide holes are made in the domed shaped house of approximate (5cm).  Now take wide (  20cm)   straight road of length (85cm) of thickness (2 cm).now it is required to hinged the road with the help strings (made of steel) having length ( 25cm ) .then it is  required to make holes in the road as well as in the card board. Then 2 of string are stitched on both the flat road as well as dome house.

History related to suspension bridges

Similarly on the opposite side of same work is done to uplift the road at a height of 10cm.

Now it is required to use the tape to bind the end of road and the contact path of domed shaped house where the hard paper road is in contact. The winding through tape should be so high that they cannot get loosen on application of high load .The winding is done on both side of attachment so that they cannot get loosen easily.it is also required to cover the paper road through plastic tape also so that the dust and other impurities can be easily removed.

 It is also required pin up the domed shaped efficiently so that no loose part remains.

Hence the construction of bridge completed

Important instruction for making the suspension bridge

1. Cardboard that is using should be little bit folded at the corner for making the length (85 cm) highly compressive supportable
2. Standard tape used should be winded properly
3. It is required to make the string straight for better holding capacity of the bridge  
4. The side of road should not be tilted without any proper cause

As per the specification provided tooth pick used should be of high tensile strength for     better holding capacity .the length of the tooth pick should be small as possible     

For good holding this bridge properly, the weight of the box should kept under the 3 kg because as the length increases the pressure on the box will be higher ,according to pressure law  P=  pgh  where height is directly proportional to pressure .

(ref-bansal publication fluid mechanics) ,as per the specification(25,15) which is quite under control weight

The piece of wood that is used must be moisture proof to reduce the weight

The main forces of suspension bridge are tension in the cable and compression in the pillar. Since all the forces on the pillar are vertically downward and they are also established by main cables so it should be made of higher strength.

The weight is transferred by the cables via towers to hold the bridge which as per the requirement is 10cm above the ground

The principal of suspension used on the large scale may also appear in the contexts less dramatic of suspension than road bridges. Light cable suspension may prove less expensive and is good enough for the footbridges. The strong grinder support in such cases where a bridge spans a gap between two domes shaped building, there is need to construct specially suspension bridges.

The three types of forces acting on any bridge is a) the dead load b) the live load c) dynamic load.

 Dead load refers to weight of the lift itself

Live load refers to the load due to traffic and due to climatic condition like precipitation, wind.

Dynamic load refers to environmental factor that go beyond normal condition and factors such as certain gust of dust and earth quake

Therefore

 dead weight =  mgh =  p*vgh 

                       = 1000*9.8*.0024

                       = 2.363kg

Live load =0.231kg

And dynamic load = 0.3656kg

 So total load = 2.7 kg

So the sum of all loads that is live weight, dynamic weight and dead weight is approximately 3 kg which is quite effective for carrying the load.

TOTAL LOAD = WEIGHT LOAD +DYNAMICS LOAD+DEAD WEIGHT LOAD

                          =   2.363kg+0.231kg+0.3565kg

                           =2.7kg

Calculation based on the forces acting on the bridge support

Different forces acting on the bridges are

1. Compressive Forces
2. Tensile Forces

Compressive Forces- such forces acts to compress the part which is in contact

Ex- in suspension bridge string connecting to the dome house apply tensile force on the domed house while domed house apply compressive forces on the string

Tensile Forces- such forces act to counter the compression is called tensile forces.

Ex-in suspension bridge, string is used to carry the tensile forces.

Total Forces= tensile forces + compression forces.

Conclusion

Thus the report of suspension bridge is completed.

References

Design Technology. Suspension Bridges - Design Technology, Viewed on 26 May 2015, https://www.design-technology.org/suspensionbridges.htm

K. Bansal; fluid mechanics viewed on 26 may,

https://roy1almechanicalbuzz.blogspot.in/2014/11/textbook-of-fluid-mechanics-by-r-k.html