Live Load

This section defines vehicular live loads, design lanes, and influence surfaces.

Navigation: Loading > Loads > Live Load

Overview

To affect live loads on your bridge, you must activate them according to your standard. Vehicle data definitions are provided before the design lane definitions. However, if you begin by defining a Design Lane, OpenBrIM will automatically assign the vehicle data.

Steps

Step 1: Import Design Lanes

Navigate to Live Load > Design Lane in the tree view.

Design Lane navigation

Click the three-dot icon on Name and select Import Design Lane to import design lanes with parameters.

Import design lanes

Imported lanes

Step 2: Configure Design Lane Parameters

The incoming lane width [ft] and vehicle & lane edge [ft] data will remain constant for this project.

Step 3: Configure Vehicles

Navigate to the Vehicles tab.

Vehicles tab

The data in the Vehicles column is automatically set when we define the Design Lane. Enter the Vehicles Impact Factor values as required.

Step 4: Configure Additional Tabs (Optional)

Review and adjust the Lane Load, Vehicle Placement Settings, and Lane Placement Settings tabs if needed.

Lane Load

Vehicle Placement

Lane Placement

Step 5: Import Vehicles

Navigate to Loads > Live Load > Vehicle.

Vehicle navigation

Click the three-dot icon on Name and select Import Vehicle. All vehicle data is automatically imported once the Design Lane has been imported.

Import vehicles

Imported vehicles

Step 6: Define Influence Surfaces

Navigate to Loads > Live Load > Influence Surface.

Influence Surface navigation

Click the three-dot icon on Stage and select the appropriate stage. After the completion of pavement on a bridge, the forces exerted by vehicles include live load, load at braking, and centripetal force.

Stage assignment

Influence surfaces

Set Roadway to R1 for each Influence Surface load.

Roadway assignment

Assign appropriate categories to each defined Influence Surface load.

Categories

Enter influence surface parameters:

• Unit Load Spacing Long. [in]: 360
• Unit Load Spacing Trans. [in]: 72

Parameters

Step 7: Configure Centrifugal Parameters

Navigate to the Centrifugal tab and enter Highway Design Speed [ft/second]: 51.3.

Centrifugal tab

Set Centrifugal Force Factor to Other Than Fatigue (1.33) for the ISCentr load.

Step 8: Define Live Load Cases

Navigate to Loads > Live Load > Live Load Case.

Live Load Case navigation

Define the Live Load Cases for which limit states will be used.

Live Load Cases

Assign Fatigue parameters as required.

Fatigue assignment

Step 9: Assign Design Lanes to Live Load Cases

Navigate to the Design Lanes tab.

Design Lanes tab

Design Lane options

Design Lane assignments

Click the three-dot icon on the Design Lane Option cell and assign design lanes to the Live Load Cases.

Verification

All live load components (design lanes, vehicles, influence surfaces, and live load cases) should be properly configured.