Structural Load Path Tracker

Understanding how loads travel through a building from their point of application to the foundation is fundamental to structural engineering. This load path tracker helps engineers visualize and quantify load distribution through multi-story structures, supporting both gravity and lateral load analysis.

Load path analysis is essential during preliminary design to ensure structural continuity—that every load has a clear, uninterrupted route to the ground. Discontinuities in the load path are among the most common causes of structural failures during earthquakes and high wind events.

How Load Paths Work

A complete load path consists of a series of structural elements that work together to transfer loads:

Gravity Load Path

For gravity loads, the path follows this sequence:

1. Applied Loads - Dead loads (structure self-weight, finishes) and live loads (occupancy, equipment) act on floor/roof surfaces
2. Deck/Slab - Distributes loads to supporting members based on tributary area
3. Beams/Girders - Collect distributed loads and transfer as concentrated reactions
4. Columns - Carry accumulated axial compression from all levels above
5. Foundation - Spreads column loads to allowable soil bearing capacity

Lateral Load Path

Lateral systems vary by structural type:

Moment Frames: Beam-column connections resist lateral loads through bending. Base shear develops overturning moment at foundation level.

Braced Frames: Diagonal members carry lateral loads in axial tension/compression, providing high stiffness with smaller member sizes.

Shear Walls: In-plane shear resistance through concrete or masonry walls. Most efficient for low to mid-rise buildings.

Key Formulas and Concepts

Tributary Area Calculations

For interior columns with equal bay spacing:

• Tributary Width = Bay Width (both directions contribute)
• Tributary Area = Bay Width × Bay Depth

For exterior columns:

• Tributary Width = Bay Width / 2 (one-sided)

Member Forces

How to Use This Calculator

This tool provides instant load path visualization for multi-story structures. Follow these steps:

Step 1: Configure Building Geometry

Step 2: Select Load Type

Step 3: Enter Applied Loads

Step 4: Choose Structural System

Step 5: Analyze Results

Review member forces in the summary table. Click "Animate Load Flow" to visualize how loads travel from application point to foundation.

Common Building Load Values

Practical Applications

Preliminary Design: Quickly estimate column sizes and beam depths based on load accumulation before detailed analysis.

Construction Sequencing: Understand which elements must be in place before others can be loaded.

Renovation Assessment: Evaluate whether existing structures can accommodate new loads or load paths.

Forensic Analysis: Trace load paths to identify potential failure points in distressed structures.

Important Limitations

This calculator provides simplified, tributary-based analysis suitable for:

• Preliminary design estimates
• Educational understanding
• Conceptual load path visualization

For final design, you must account for:

• Load combinations per ASCE 7
• Member capacity checks per material design codes
• Connection design
• Second-order effects (P-delta)
• Seismic design categories and response modification factors

Verification Log

References

1. ASCE 7-22: Minimum Design Loads and Associated Criteria for Buildings and Other Structures. American Society of Civil Engineers, 2022.
2. IBC 2024: International Building Code, Chapter 16 - Structural Design. International Code Council, 2024.
3. AISC Steel Construction Manual, 15th Edition. American Institute of Steel Construction, 2017.
4. ACI 318-19: Building Code Requirements for Structural Concrete. American Concrete Institute, 2019.

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This calculator is for educational and preliminary assessment purposes. All structural designs must be verified by a licensed Professional Engineer.