A fiber hinge typically refers to a structural element or, more commonly, a model used in structural mechanics to represent the behavior of a hinge-like connection or region.
Understanding the Fiber Hinge Model
Based on the provided reference, the fiber hinge model is a method used to analyze and simulate how a structure behaves when it undergoes bending or deformation that resembles a hinge. This model is built upon fundamental principles of engineering and material science:
Core Principles
- Bar-System Structure Mechanics: The model simplifies the complex continuous material of a structural element into a system of discrete "bars" or "fibers". Each fiber represents a small portion of the material's cross-section.
- Uniaxial Constitutive Relation: The behavior of each individual fiber is governed by its material's "constitutive relation." In this context, "uniaxial" means the relationship describes how the fiber behaves under stress (force per unit area) and strain (deformation) applied along only one direction (its axis).
How it Works
The mechanical response of the overall "hinge" is determined by the combined behavior of all these individual fibers.
- Each fiber is characterized by the uniaxial stress-strain relationship of its specific material. This relationship defines how much stress is required to cause a certain amount of strain in that fiber.
- When the structure bends, some fibers are stretched (tension), and others are compressed. The model calculates the stress and strain in each fiber based on its position and the material's properties.
- By integrating the forces in all fibers across the cross-section, the model can predict the overall moment (bending force) and rotation behavior of the hinge.
Applications
Fiber hinge models are particularly useful in simulating the non-linear behavior of materials like reinforced concrete or steel under extreme loading conditions, such as during earthquakes. They allow engineers to understand how plastic hinges form and how structures deform beyond their elastic limits.
