STA GUI - Structural Analysis Tool

Overview

STA is a Python-based GUI application for structural analysis, built with Tkinter. It provides interactive tools for modeling, analyzing, and visualizing structural elements like beams, frames, and trusses.

Features

• File Loading: Supports loading structural models from .zap files with automatic encoding detection (UTF-8 or Latin-1).
• Interactive Canvas: Zoom, pan, and fit-to-screen functionality.
• Results Visualization: Display bending moment diagrams, shear force diagrams, axial forces, and displacements.
• Keyboard Shortcuts:
  • Ctrl+Z: Undo
  • Ctrl+Y: Redo
  • Ctrl+0: Reset zoom to 100% and center model
  • +/-: Zoom in/out
• Status Bar: Shows current scale, mouse position, and grid/snap status.
• Grid and Snap: Toggle grid display and snapping for precise modeling.

Installation

1. Ensure Python 3.x is installed.
2. Install required dependencies (if any, e.g., NumPy):

   pip install numpy
   

3. Run the application:

   python Sta.py
   

Usage

• Load example files from the EXAMPLES/ folder.
• Use mouse to select, add nodes/members, and apply loads.
• Press Ctrl+0 to reset zoom and center the model.
• Analyze the structure and view results in different modes (shear, bending, etc.).

Debugging and Update Log

Overview of Debugging

• Primary Objectives: Fix bugs in STA GUI, including file loading failures, runtime errors, diagram inconsistencies, encoding issues, GUI visibility after loading, and zoom/pan features.
• Main Issues Encountered:
  • File loading failures (encoding, parsing errors).
  • Runtime crashes (division by zero, attribute errors).
  • Diagram mismatches between polyline and line rendering.
  • Image disappearing after loading (viewport centering).
  • Zoom reset (Ctrl+0) hiding the model.
• Resolution Approach: Iterative testing, code fixes, and validation with py_compile and runtime execution.

Detailed Updates

1. File Loading Fixes (loadsave.py):

   • Added encoding detection (try UTF-8, fallback to Latin-1).
   • Fixed parsing errors (typos, zero length/material checks).
   • Implemented auto-fit after loading for proper centering.

2. Runtime Error Fixes (General):

   • Added checks for division by zero and missing attributes.
   • Unified bending moment diagram calculations for consistent rendering.

3. GUI and Rendering Updates (canvas.py, draw.py):

   • Added fit-to-screen, middle-mouse pan, keyboard zoom (+/-), and scale display.
   • Fixed viewport centering post-loading.

4. Zoom and Coordinate Fixes (functions.py, canvas.py):

   • Updated canvasCoords and trueCoords to consistently apply mouseAnchor offset.
   • Revised zoom() and zoomReset() for accurate centering.
   • Ctrl+0 now centers the model without hiding it.

Current Status

• Completed Features: File loading, runtime fixes, diagram consistency, auto-fit, pan, keyboard zoom, status bar.
• Resolved Issues: Zoom reset no longer hides the model.
• Testing: Validated with py_compile (no errors) and runtime execution (exit code 0).

Key Modules

• Sta.py: Main GUI and event handlers.
• canvas.py: Canvas management, zoom, pan, redraw.
• functions.py: Coordinate transformations.
• loadsave.py: File I/O and auto-centering.
• draw.py: Rendering functions.
• classes.py: Data models.
• action.py: Undo/redo logic.

Notes

• Scrollregion is fixed to (-100000, -100000, 100000, 100000) for large models.
• Coordinate system: Canvas Y increases downward; transformations handle scaling and anchoring.
• Test with example files in EXAMPLES/ to verify functionality.

Recent Fixes (April 2026)

Bending Moment Diagram Consistency

• Adjusted member direction to be consistent based on global coordinates (vertical: bottom-to-top, horizontal: left-to-right) to ensure bending moment diagrams display the same regardless of drawing order.
• Modified Member.__init__ and update in classes.py to swap nodes automatically.
• Removed flip logic in functions.py and run.py for consistent sign convention.

Bug Fixes

• Division by Zero: Added check in run.py to skip members with zero length.
• Index Errors: Added bounds checks in classes.py, draw.py, and other files to prevent crashes from invalid node/member indices.
• Square Root Negative: Clamped result in functions.py findProjection to avoid ValueError.
• Load/Save Integrity: Added original_nodes in Member class and updated loadsave.py to save original node indices, preventing file corruption from direction swaps.

Testing

• Runtime tests pass with improved error handling.
• Load/save operations preserve file structure.
• Bending moment diagrams are now consistent across different drawing directions.