What Bridge Design Holds the Most Weight?

What is the strongest bridge design?

This is the question I get asked the most.

Before we can begin to look for an answer, I need to know more specifically what you are looking for. Are you looking for the the strongest Type of Bridge, such as:

Bridge Types:

  • Beam
  • Arch
  • Truss
  • Suspension

Each of these has advantages and disadvantages. Each type could be the best for a specific situation, and there are a ton of factors that engineers must consider when choosing which one to use.

You can learn more about each of these by clicking the link above.

Perhaps you are asking about which truss design is the strongest. Since most model bridges are truss bridges, this is a great question to ask.

Truss Designs:

  • Warren
  • Pratt
  • Howe
  • Many More
Is the the Pratt, Howe, or the Warren truss stronger? Each of these designs, along with the host of variations, was developed for a specific reason or to make better use of existing or new materials or construction methods. Their history is fascinating, and you definitely should check out the articles about each of them.

Each truss design takes a load or force and spreads it out, eventually transferring it to the bridge abutments and/or piers.

So Which Truss is Strongest?

You really are going to pin me down to answering this question, aren’t you?

In my mind, none of these truss designs has an inherent advantage over the others in a very broad and general sense.

However, when we are considering small model bridges, I have a hard time seeing the Howe as efficient as the Pratt. But is one of these better than the most common, the Warren? You can explore my reasoning on this throughout this website.

Why don’t you take a look at each design and comment below which on you think is the best, especially in the context of model bridges.

72 thoughts on “What Bridge Design Holds the Most Weight?”

  1. Thank you for the article, very useful information!
    I need to build a small truss ( about 75cm span length between supports, and a maximum height of 25cm) using Balsa wood and glue. It evaluated according to the best strength to weight ratio. Strength being the load that my truss can hold and weight being the weight of my truss. Am I correct to guess that a warren truss will be the best choice?
    Thank you!

    Reply
  2. I’m building a balsa bridge that needs to span 36″. It only needs to hold 25lbs centered. The criteria for winning is to hold 25lbs with the most efficiency. My initial thought was to make an arch super and sub structure that overlaps on the main chord, with warren or K webbing(can post a sketch if it helps). Just wondering if anyone has experience making a bridge of this span length and which truss types work better over such a distance. Thanks!

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  3. How do the proportions and angles of the triangles in the truss allow it to function? Does geometry play a role or is it all physics?

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  4. Hi I Made A Warren Truss Bridge with The Side Members opposite To each other(the apex of one triangle faces base of triangle in front)…….will the bridge hold good weight

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  5. What design would you recommend for a bridge building competition, where thin balsa wood sheets are used? We are allowed to use a laser cutter to create it.

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    • You probably don’t want to laser cut your design out of a sheet of wood. The grain of the wood will not be oriented in the best way, and it will be very weak.

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    • The navy uses a built up wood beam for building at Great Lakes. They are about 120′ wide and 1000′ or more in length. Though they do have large blocks of comcrete outside, the same design a multi glued up wood arched beam then just drop lines for your deck. More weight on a arch if ends don’t move the arch just gets stronger.

      Reply
  6. I’m building a bridge with a bowstring superstructure and a Warren substructure.

    What benefits does a substructure add, in your opinion, other than diverting force from the middle to the sides, and is a bowstring truss a better option than a Warren or Pratt?

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    • Do you have a example picture of your design. I want to make sure I understand what you are building before trying to answer.

      Reply
  7. Great article, perhaps the different effectiveness of design depends on if the material used in the bridge is better at supporting members in tension or compression? Because if you had a material with a high maximum compression but a low maximum tension you’d surely go with the design that places less stress on the members in tension. Honestly that was what I was looking for when I came here, and after designing my bridge I hope I remember to come back and tell you the answer.

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  8. i really like this website because my challenge teacher Mrs. Simmons really likes us to go to this website every Tuesday and Thursday!

    thank you for making this website!

    Reply
  9. Worthless article because you don’t answer the question. Pound for pound Howe Truss bridges are worthless when compared against Warren or Pratt. The real question is which is more efficient pound for pound: Warren or Pratt? You do not answer that question.

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  10. I would like a bit more detail because I am doing an assignment on bridges and I have to make a model that can hold a lot of weight. The information wasn’t very precise but it was still very informational.

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  11. im doing a model truss bridge and was wondering which design would hold the most weight yet be made of the least amount of material. i was thinking the warren.

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  12. I am doing an EPQ about building the strongest bridge and was wondering which it would be? If it is a truss bridge, what materials would I need to physically make one roughly 1-2 meters long?
    Thanks

    Reply
    • Usually if it is a school project, they would give you balsa wood and wood glue. In that case, you would want to make a lot of triangle or crossing shapes, like a parker bridge or a double intersecting warren bridge. and these are just truss bridges! It all depends on what kind of bridge you are building. (if you do not know what the bridges are that I just listed, you can look them up online.)

      Reply

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