Karamba3D v1.3.3
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English 英文
  • Welcome to Karamba3D
  • 1: Introduction
    • 1.1: Installation
    • 1.2: Licenses
      • 1.2.1: Cloud Licenses
      • 1.2.2: Network Licenses
        • 1.2.2.1: Network license (archived)
      • 1.2.3: Temporary Licenses
      • 1.2.4: Standalone Licenses
  • 2: Getting Started
    • 2: Getting Started
      • 2.1: Karamba3D Entities
      • 2.2: Setting up a Structural Analysis
        • 2.2.1: Define the Model Elements
        • 2.2.2: View the Model
        • 2.2.3: Add Supports
        • 2.2.4: Define Loads
        • 2.2.5: Choose an Algorithm
        • 2.2.6: Provide Cross Sections
        • 2.2.7: Specify Materials
        • 2.2.8: Retrieve Results
      • 2.3: Physical Units
      • 2.4: Quick Component Reference
  • 3: In Depth Component Reference
    • 3.1: Model
      • 3.1.1: Assemble Model
      • 3.1.2: Disassemble Model
      • 3.1.3: Modify Model
      • 3.1.4: Connected Parts
      • 3.1.5: Activate Element
      • 3.1.6: Line to Beam
      • 3.1.7: Connectivity to Beam
      • 3.1.8: Index to Beam
      • 3.1.9: Mesh to Shell
      • 3.1.10: Modify Element
      • 3.1.11: Point-Mass
      • 3.1.12: Disassemble Element
      • 3.1.13: Make Beam-Set 🔷
      • 3.1.14: Orientate Element
      • 3.1.15: Select Element
      • 3.1.16: Support
    • 3.2: Load
      • 3.2.1: Loads
      • 3.2.2: Disassemble Mesh Load
      • 3.2.3: Prescribed displacements
    • 3.3: Cross Section
      • 3.3.1: Beam Cross Sections
      • 3.3.2: Shell Cross Sections
      • 3.3.3: Spring Cross Sections
      • 3.3.4: Disassemble Cross Section 🔷
      • 3.3.5: Beam-Joint Agent 🔷
      • 3.3.6: Beam-Joints 🔷
      • 3.3.7: Eccentricity on Beam and Cross Section 🔷
      • 3.3.8: Modify Cross Section 🔷
      • 3.3.9: Cross Section Range Selector
      • 3.3.10: Cross Section Selector
      • 3.3.11: Cross Section Matcher
      • 3.3.12: Generate Cross Section Table
      • 3.3.13: Read Cross Section Table from File
    • 3.4: Material
      • 3.4.1: Material Properties
      • 3.4.2: Material Selection
      • 3.4.3: Read Material Table from File
      • 3.4.4: Disassemble Material 🔷
    • 3.5: Algorithms
      • 3.5.1: Analyze
      • 3.5.2: AnalyzeThII 🔷
      • 3.5.3: Analyze Nonlinear WIP
      • 3.5.4: Large Deformation Analysis
      • 3.5.5: Buckling Modes 🔷
      • 3.5.6: Eigen Modes
      • 3.5.7: Natural Vibrations
      • 3.5.8: Optimize Cross Section 🔷
      • 3.5.9: BESO for Beams
      • 3.5.10: BESO for Shells
      • 3.5.11: Optimize Reinforcement 🔷
      • 3.5.12: Tension/Compression Eliminator 🔷
    • 3.6: Results
      • 3.6.1: ModelView
      • 3.6.2: Deformation-Energy
      • 3.6.3: Nodal Displacements
      • 3.6.4: Principal Strains Approximation
      • 3.6.5: Reaction Forces 🔷
      • 3.6.6: Utilization of Elements 🔷
      • 3.6.7: BeamView
      • 3.6.8: Beam Displacements 🔷
      • 3.6.9: Beam Forces
      • 3.6.10: Resultant Section Forces
      • 3.6.11: ShellView
      • 3.6.12: Line Results on Shells
      • 3.6.13: Result Vectors on Shells
      • 3.6.14: Shell Forces
    • 3.7: Export 🔷
      • 3.7.1: Export Model to DStV 🔷
    • 3.8 Utilities
      • 3.8.1: Mesh Breps
      • 3.8.2: Closest Points
      • 3.8.3: Closest Points Multi-dimensional
      • 3.8.4: Cull Curves
      • 3.8.5: Detect Collisions
      • 3.8.6: Get Cells from Lines
      • 3.8.7: Line-Line Intersection
      • 3.8.8: Principal States Transformation 🔷
      • 3.8.9: Remove Duplicate Lines
      • 3.8.10: Remove Duplicate Points
      • 3.8.11: Simplify Model
      • 3.8.12: Element Felting 🔷
      • 3.8.13: Mapper 🔷
      • 3.8.14: Interpolate Shape 🔷
      • 3.8.15: Connecting Beams with Stitches 🔷
      • 3.8.16: User Iso-Lines and Stream-Lines
  • Troubleshooting
    • 4.1: Miscellaneous Questions and Problems
      • 4.1.1: Installation Issues
      • 4.1.2: Purchases
      • 4.1.3: Licensing
      • 4.1.4: Runtime Errors
      • 4.1.5: Definitions and Components
      • 4.1.6: Default Program Settings
    • 4.2: Support
  • Appendix
    • A.1: Release Notes
      • Work in Progress Versions
      • Version 1.3.3
      • Version 1.3.2 build 190919
      • Version 1.3.2 build 190731
      • Version 1.3.2 build 190709
      • Version 1.3.2
    • A.2: Background information
      • A.2.1: Basic Properties of Materials
      • A.2.2: Additional Information on Loads
      • A.2.3: Tips for Designing Statically Feasible Structures
      • A.2.4: Hints on Reducing Computation Time
      • A.2.5: Natural Vibrations, Eigen Modes and Buckling
      • A.2.6: Approach Used for Cross Section Optimization
    • A.3: Bibliography
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  1. 3: In Depth Component Reference
  2. 3.5: Algorithms

3.5.7: Natural Vibrations

Previous3.5.6: Eigen ModesNext3.5.8: Optimize Cross Section 🔷

Last updated 4 years ago

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In case you want to know how and at which frequency a structure vibrates use the “NaturalVibrations”-component. Fig. 3.5.7.1 shows a simply supported steel beam IPE100 of length10m10m10mwith a point-mass at mid-span in its 24th natural vibration mode.

The mass of beams and trusses enters the calculation of natural vibrations with the values derived from their material weight. Karamba3D uses consistent mass matrices for beam elements. For truss and shell elements a lumped approach is applied.

At nodes additional masses (see section ) can be defined to simulate the effect of e.g. concrete slabs (these normally make up the majority of mass in high-rises) in an approximate manner. These masses are assumed to have translational inertia only.

Karamba3D scales the resulting vibration modes vi⃗\vec {v_i}vi​​ in such a way that their largest component is 1. They get attached to a model as result-cases which can be viewed via a “ModelView”-component. The calculation of modal mass and participation factors are based on the modal displacements as scaled in the above described manner.

3.1.11
Fig. 3.5.7.1: Natural vibration mode of a simply supported steel beam with a point-mass at mid-span.