Why is the Pratt truss bridge the best?

Why is the Pratt truss bridge the best?

It is easy to construct, and is a solid choice for a model bridge design. What makes it so good, and gives it an advantage over the Howe truss, is how it spreads out the forces when under load. The longer, angled truss members are under tension. The shorter, vertical members are under compression.

Which is better Pratt or Howe truss?

The Pratt truss disspipated the load more efficiently than the Howe truss, although both truss bridges dissipated the force significatnly more effectively than the beam bridge. In addition, the Pratt truss deflected the least and held the most, on average, while the beam bridge deflected the most and held the least.

Why was the Pratt truss bridge invented?

This bridge was built in 1902 to carry the Patuxent Branch of the Baltimore and Ohio Railroad over the Little Patuxent River.

What type of truss is the strongest?

Of the three bridge designs I tested (warren-truss, pratt-truss, k-truss) the warren-truss held the most weight. I tested each design 5 times and the average for the warren was 43.6 pounds. The k average was 31 pounds and the pratt design was the weakest and averaged 13.6 pounds.

What is good about a Pratt truss?

Pratt Truss This simplifies and produces a more efficient design since the steel in the diagonal members (in tension) can be reduced. This has a few effects – it reduces the cost of the structure due to more efficient members, reduces the self-weight, and eases the constructability of the structure.

How does the Pratt truss work?

The basic form of Pratt truss includes triangular truss design whose diagonal members slope toward the center of the bridge. When under load, this design makes diagonal members feel tension (the force that expands the object apart), while vertical members feel suspension (the force that pushes objects into one self).

What is the difference between Warren and Pratt truss?

Warren truss contains a series of isosceles triangles or equilateral triangles. Pratt truss is characterized by having its diagonal members (except the end diagonals) slanted down towards the middle of the bridge span.

What is the purpose of the truss bridge?

Given that a triangle cannot be distorted by stress, a truss gives a stable form capable of supporting considerable external loads over a large span. Trusses are popular for bridge building because they use a relatively small amount of material for the amount of weight they can support.

What is the difference between Howe and Pratt truss?

The main differences are that the Pratt truss has no force on the ends and the compression members are vertical. The Howe truss has no force on the center and the tension members are vertical instead. – The Howe truss has no net force in the center, where the load will be placed.

When was Pratt truss invented?

1844
The Pratt truss was first developed in 1844 under patent of Thomas and Caleb Pratt. Prevalent from the 1840s through the early twentieth century, the Pratt has diagonals in tension, verticals in compression, except for the hip verticals immediately adjacent to the inclined end posts of the bridge.

What are disadvantages of the Pratt truss bridge?

This type of bridge was invented in 1844 by Thomas and Caleb Pratt. It is efficient because the longer diagonal members are in tension and the shorter vertical members are in compression. The disadvantage is that this kind of bridge is very expensive .

What is the strongest truss bridge?

warren-truss design will be the strongest because it is the simplest design and spreads the weight of the load evenly over the bridge. Methods/Materials Popsicle sticks and glue were used to build 3 different bridge designs: Pratt truss, Warren truss, and K truss. 5 identical models of each design were built. All 15 bridge were the same length.

What is the strongest type of bridge?

Many of the strongest bridges in the world are credited to the strength because of the material used in the making and the design as well. The Rolling Bridge in London opened in 2004 is a truss bridge and is considered the strongest bridge in the world.

What are the different types of truss bridges?

Truss Bridges There are 4 different, basic types of truss bridges: Warren, Pratt, Howe and K Truss. (In order, below.) A truss bridge is a bridge composed of connected elements (typically straight) which may be stressed from tension, compression, or sometimes both in response to loads. Truss bridges are one of the oldest types of modern bridges.