Precast Bridge Girder Configurator

A Dynamo + Revit Tool for Rapid Bridge Girder Design and Visualization

1. Dynamo Script

Attached my.dyn and .rvt file:

2units_AbhishekVijayan_Module9.dyn

2units_AbhishekVijayan_Module9.rvt

2. Documentation (“ReadMe”)

Catchy Tool Name

BridgeGEN: Parametric Precast Bridge Configurator

Brief Overview

BridgeGEN is a Dynamo-based tool that enables structural engineers, students, and contractors to rapidly generate and evaluate parametric models of precast concrete bridges within Revit.

Define the bridge span, width, girder number and spacing, deck thickness, column size, and more—then instantly visualize the bridge, export geometry to Revit, and receive live engineering feedback.

Key features:

• Parametric 3D bridge model with real-time updates
• Structural code checks for flexure, span/depth, and more
• Embodied carbon and weight calculations
• Warnings if code or constructability limits are exceeded
• Material quantity takeoff and schedules
• Export-ready geometry for Revit documentation

Key Inputs

• Span Length (m)
• Bridge Width (m)
• Girder Spacing (m)
• Deck Thickness (m)
• Column Height (m)
• Column Radius (m)
• (Girder Depth = 1.5 m and Girder Width = 0.4 m are fixed for this prototype)
• Concrete Strength (fck, MPa)
• Embodied Carbon Intensity (kg CO₂e/m³)

Methodology - Underlying Logic and Workflow

The methodology integrates parametric modeling, structural engineering checks, material quantification, and sustainability assessment in a single Dynamo workflow:

1. Parametric Geometry Generation

• All bridge elements—girders, deck slab, and columns—are modeled as Dynamo solids.
• Dimensions and positions are determined by user-set parameters (span length, width, girder spacing, etc.).
• Girders are arrayed across the bridge width; the deck is placed atop; columns are positioned at girder ends and midspan.

2. Load Calculations

• Girder area:
$$A_{girder} = \text{girder width} \times \text{girder depth}$$
• Deck area per girder:

• Self-weight per meter per girder:
$$w_{self} = (A_{girder} + A_{deck,girder}) \times 24 \ \text{kN/m}^3$$
• Total factored load (per girder):
$$w_{tot} = 1.2 \times (w_{self} + w_{dead}) + 1.6 \times w_{live}$$

where

$$w_{dead} = superimposed dead load (e.g., 3 kN/m) ; w_{live} = live load (e.g., 10 kN/m)$$

3. Structural Engineering Checks

• Span-to-Depth Ratio:

Flagged if outside code limits (typically 18–25).

• Flexural (Moment) Check:
• Maximum factored moment at midspan:
$$M_u = \frac{w_{tot} \cdot L^2}{8}$$

where L = span length

• Section modulus (rectangular girder):
$$Z = \frac{b \cdot d^2}{6}$$

where b = girder width, d = girder depth

• Nominal flexural capacity:
$$M_n = \phi \cdot f_{ck} \cdot Z$$

where f{ck} = concrete strength (MPa), phi = strength reduction factor (e.g., 0.9)_

• Check: If M_n > M_u, display "OK"; else, "Flexural capacity exceeded".

4. Material Quantities & Sustainability

• Concrete volume (each component):
• Girder:
$$\text{width} \times \text{depth} \times \text{length} \times \text{number of girders}$$
• Deck:
$$\text{thickness} \times \text{width} \times \text{span length}$$
• Columns:
$$\pi r^2 \times \text{height} \times \text{number of columns}$$
• Total Concrete Volume:

Sum of all components.

• Embodied Carbon:
$$\text{CO}2\text{e}{total} = \text{Total Concrete Volume} \times \text{ECI}$$

where ECI = embodied carbon intensity (e.g., 300 kg CO₂e/m³)

5. Constructability/Transportability Check

• Girder unit weight:
$$W_{girder} = \text{volume per girder} \times 24 \ \text{kN/m}^3$$
• Compared to typical transport/erection limits (e.g., max 40 tons/unit).

6. Automated Feedback

• If any check fails (e.g., code ratio exceeded, flexural capacity not met, girder too heavy), the tool provides a warning message to the user for immediate design revision.

All calculations are automated, so any change in user input instantly updates the model, quantities, and code checks.

Outputs

• 3D bridge geometry (girders, deck, circular columns at front/midspan/end)
• Engineering summary:
• Structural checks:
• Span-to-depth ratio (code-based)
• Flexural capacity vs. demand
• Material quantities:
• Concrete volume (girders, deck, columns, total)
• Self-weight, dead load
• Sustainability metrics:
• Total embodied carbon (kg CO₂e)
• Warnings:
• Code violations, constructability/transport alerts

How to Use

• Open 2units_AbhishekVijayan_Module9.dyn in Dynamo or Dyanmo Player for Revit.
• Set inputs at the top (span, width, girder spacing, etc.—all grouped for user-friendliness).
• Run the script to generate your bridge geometry and see results live in Dynamo and Revit.
• Review engineering checks and material takeoff at the script’s end (see Watch nodes and results group).
• Adjust parameters as needed to explore alternatives, improve compliance, or optimize design.

Teaser Image

Demo Video