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Live Load Patterning is a feature of the beam solver that automatically generates optimized load combinations based on structural configuration, helping identify critical loading scenarios for design.

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How It Works

Live load patterning is enabled by passing a vector of load types to be patterned to the beam solver. The solver then automatically generates combinations based on the structural layout.

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Basic Configuration

To enable load patterning, specify the load types in the loadPattern parameter: 
{
  "type": "remote",
  "referenceId": "beam_analysis",
  "solver": "beam",
  "inputs": {
    "loadPattern": ["L"],
    // ... other beam solver inputs
  }
}
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loadPattern
array
required
Vector containing the load types to be patterned (e.g., ["L"] for live loads, ["L", "Lr"] for live and roof live loads)

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Automatic Combination Generation

Behind the scenes, the solver automatically generates load combinations based on:
  1. Support locations (default behavior)
  2. Internal pins (treated as pattern break points, even though they’re not technically supports)
  3. Brace locations (when configured)

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Advanced Configuration

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Load Pattern Basis

You can control what structural elements are used to determine patterning locations with the loadPatternBasis parameter:
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loadPatternBasis
string
default:"supports"
Defines what structural elements determine pattern boundaries:
  • "supports": Based on support locations (default)
  • "braces": Based on any brace locations
  • "Brace X": Based on specific brace type X only
{
  "inputs": {
    "loadPattern": ["L"],
    "loadPatternBasis": "supports", // or "braces" or "Brace 1"
    // ... other inputs
  }
}

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Patterning Behavior

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Complete Spans

For loads that completely cover individual spans, the solver will pattern by including or excluding the load from each span to find maximum effects.

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Partially-Loaded Spans

If a load extends across more than one span but doesn’t completely cover any span, it will still be included in the patterning analysis.
Example of load patterning with partially loaded spans
The image above shows how loads that partially cover spans are still considered in the patterning process, ensuring comprehensive analysis of all loading scenarios.

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Implementation Example

{
  "type": "remote",
  "referenceId": "continuous_beam_analysis",
  "solver": "beam",
  "inputs": {
    "spans": [
      {"length": 6000, "loads": [...]},
      {"length": 8000, "loads": [...]},
      {"length": 6000, "loads": [...]}
    ],
    "supports": [
      {"location": 0, "type": "pin"},
      {"location": 6000, "type": "roller"},
      {"location": 14000, "type": "roller"},
      {"location": 20000, "type": "pin"}
    ],
    "loadPattern": ["L"], // Pattern live loads
    "loadPatternBasis": "supports",
    "combinations": [
      {"name": "ULS", "factors": {"D": 1.2, "L": 1.6}},
      {"name": "SLS", "factors": {"D": 1.0, "L": 1.0}}
    ]
  }
}

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Benefits of Load Patterning

  1. Automatic Optimization: Finds the most critical loading scenarios without manual specification
  2. Comprehensive Analysis: Considers all possible load arrangements that could produce maximum effects
  3. Code Compliance: Ensures analysis meets structural code requirements for live load patterning
  4. Efficiency: Reduces manual effort in defining load combinations

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Best Practices

  1. Load Type Selection: Include all relevant variable loads that should be patterned (typically live loads, roof live loads, snow loads)
  2. Basis Selection:
    • Use "supports" for most continuous beam scenarios
    • Use "braces" when lateral bracing significantly affects behavior
    • Use specific brace types when different brace types have different structural significance
  3. Combination Design: Ensure your load combinations work effectively with patterned loads
  4. Result Interpretation: Remember that patterned results represent enveloped maximum/minimum values across all pattern scenarios

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Output Interpretation

When load patterning is enabled:
  • Results represent enveloped maximum and minimum values
  • Critical load patterns are automatically identified
  • Design forces consider all possible loading arrangements
  • Output includes information about which pattern produced critical results
Load patterning is particularly important for continuous beam analysis where different loading arrangements can produce significantly different internal forces and deflections.
When using load patterning with complex loading scenarios, ensure that your load definitions are compatible with patterning algorithms and that all relevant loads are properly categorized by type.
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