Static and kinematic determinacy

In summary, static determinacy refers to a state where a structure can be fully analyzed using the equations of static equilibrium, while kinematic determinacy involves the use of kinematic equations and may result in some uncertainty in the solution. A structure is considered statically determinate if the number of unknown forces and moments is equal to the number of equilibrium equations available, and it can also be both statically and kinematically determinate, making it overconstrained. The advantages of a statically determinate structure include a more accurate and efficient design process, as well as less susceptibility to failure. The degree of kinematic indeterminacy affects a structure by potentially leading to a less reliable design, making a lower degree of kinematic indeterminacy preferred for a
  • #1
v_pino
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What is the difference between a structure being statically indeterminate and being kinematic?

Are they the same?
 
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  • #2
Actually I don't know the kinematic indeterminacy but I know staticly indeterminate structure.
Basically, in a indetermine structure you cannot analyse system by using simple static.You have to have somethig more such as deflection or something like that.The importance of indeterminete system is when the strcutre fails( ex failure of a beam) the structure still stands by disturrbing the forces another beams. Thus, all the structures have indetermancy.
 
  • #3


No, static and kinematic determinacy are not the same. They refer to different aspects of a structure's stability and behavior.

Static determinacy refers to a structure's ability to resist external forces and maintain equilibrium without any movement or deformation. A statically determinate structure is one where the internal forces and reactions can be calculated using the equations of static equilibrium. This means that the structure has a well-defined and unique solution for the internal forces and reactions at all points.

On the other hand, kinematic determinacy refers to a structure's ability to resist external forces and maintain equilibrium while allowing for some movement or deformation. A kinematically determinate structure is one where the internal forces and deformations can be calculated using the equations of kinematic compatibility. This means that the structure has a well-defined and unique solution for the internal forces and deformations at all points.

The main difference between static and kinematic determinacy is that static determinacy only considers the external forces and reactions, while kinematic determinacy also takes into account the internal forces and deformations. Therefore, a structure can be statically determinate but kinematically indeterminate, meaning it can resist external forces without any movement or deformation, but the internal forces and deformations cannot be uniquely determined.

In summary, the difference between a structure being statically indeterminate and being kinematic is that static indeterminacy refers to a lack of unique solution for external forces and reactions, while kinematic indeterminacy refers to a lack of unique solution for both external and internal forces and deformations.
 

FAQ: Static and kinematic determinacy

What is the difference between static and kinematic determinacy?

Static determinacy refers to a state where a structure can be fully analyzed using the equations of static equilibrium. This means that all the forces and moments acting on the structure can be determined and there is no uncertainty in the solution. On the other hand, kinematic determinacy refers to a state where a structure can be analyzed using the equations of kinematics, which involve the geometry and motion of the structure. In this case, there may be some uncertainty in the solution due to the nature of kinematic equations.

How can I determine if a structure is statically determinate?

A structure is considered statically determinate if the number of unknown forces and moments is equal to the number of equilibrium equations available to solve for them. This means that the structure must have at least as many support reactions as the number of external forces acting on it. If the structure has more supports or more equations than required, it is considered statically indeterminate.

Can a structure be both statically and kinematically determinate?

Yes, it is possible for a structure to be both statically and kinematically determinate. This means that the structure can be fully analyzed using both static and kinematic equations, providing two independent solutions for the forces and moments acting on it. In this case, the structure is considered to be overconstrained, as there are more equations available than needed to solve for the unknowns.

What are the advantages of a statically determinate structure?

A statically determinate structure is advantageous because it can be fully analyzed using simple and reliable equations of static equilibrium. This allows for a more accurate and efficient design process, as the forces and moments acting on the structure can be determined with certainty. Additionally, statically determinate structures are less prone to failure due to overloading or unexpected loads, as the reactions and internal forces can be accurately calculated.

How does the degree of kinematic indeterminacy affect a structure?

The degree of kinematic indeterminacy refers to the number of kinematic equations that must be satisfied to determine the unknown forces and moments in a structure. The higher the degree of kinematic indeterminacy, the more uncertain the solution may be. This can lead to a less reliable design, as there may be multiple solutions that satisfy the kinematic equations. Therefore, a lower degree of kinematic indeterminacy is preferred for a more precise and accurate analysis of a structure.

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