Statically Indeterminate Structure Advantages

In summary, it is common for real world structures to be statically indeterminate due to their construction. However, statically determinate structures have the advantage of being able to easily calculate internal forces and design for minimum weight.
  • #1
member 392791
Hello,

I was wondering why it might be advantageous in some applications to create a structure that is statically indeterminate?

Thanks
 
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  • #2
I would rather turn the question round. Most "real world" structures turn out to be statically indeterminate because of the way they are constructed, whether you like it or not. For example you can design the roof structure of a house using statically determinate trusses, but the walls of a traditional (european) house built from brick or stone are not statically determinate. Even with a modern steel-framed building, including the diagonal members that are needed to make a rigid statically determinate frame would be a problem, unless you like triangular windows, or beams running diagonally across the rooms, etc!

On the other hand statically determinate structures have one big advantage. The internal forces and reaction forces only depend on the geometry of the structure, and not what it is made from. So it is easy to design a "minimum weight" determinate structure: calculate the internal forces, and then use the least amount of material that will withstand them. (OK, that ignores the weight of the structure itself, but you get the general idea).
 

What is a statically indeterminate structure?

A statically indeterminate structure is a type of structure in which the reactions and internal forces cannot be determined solely by applying the equations of static equilibrium. This means that the structure has more unknown forces or displacements than available equations.

What are the advantages of statically indeterminate structures?

Statically indeterminate structures have several advantages, including:

  • Increased stability and strength due to redundancy in load carrying capacity.
  • Ability to distribute loads more evenly, reducing localized stress concentrations.
  • Allows for more efficient use of materials, reducing costs.
  • Increased resistance to external forces such as wind and earthquakes.
  • Ability to withstand larger deformations without failure.

What are the disadvantages of statically indeterminate structures?

While there are many advantages to using statically indeterminate structures, there are also some disadvantages that need to be considered:

  • Increased complexity in analysis and design, requiring more advanced engineering knowledge.
  • More difficult to construct and may require specialized construction techniques.
  • May be more susceptible to unexpected failure modes due to the presence of unknown internal forces.
  • May require additional maintenance and inspection due to increased stress concentrations.

How are statically indeterminate structures analyzed?

Statically indeterminate structures are analyzed using advanced structural analysis methods such as the flexibility and stiffness methods. These methods take into account the additional unknown forces and displacements to determine the internal forces and reactions in the structure.

What are some examples of statically indeterminate structures?

Some common examples of statically indeterminate structures include continuous beams, trusses with multiple redundant members, and arch or cable-stayed bridges. Other examples include buildings with irregular shapes or complex loadings, and complex mechanical systems such as aircraft wings and fuselages.

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