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    POWERFUL INFLUENCE SURFACE ALGORITHMS DELIVER TIME SAVINGS
    LARSA 4D’s influence surface algorithms automatically position design lanes and quickly compute
    the worst vehicle loading configuration for bridge decks.
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    UNRIVALED SUPPORT FOR ADVANCED BRIDGE PROJECTS
    LARSA 4D's influence surface based live load computes the most extreme conditions at
    any point of the structure in real-time as they're needed.

Influence Line & Surface Analysis

In LARSA 4D, influence lines and surfaces include algorithms to automatically find the worst-case live load scenarios by positioning vehicles and uniform lane loads to maximize the effect.

LARSA 4D Live Load Analysis

Influence surface analysis is the latest methodology for live load analysis, which extends the notion of an influence line onto a 2D surface on plate-deck models. In LARSA 4D, both influence lines and influence surfaces are available to quickly compute the worst case loading configurations on bridge decks, including bridges with curved and skewed roadways and nonparallel curb lines.

The influence surface algorithms integrated in LARSA 4D automatically determine the transverse location of the design lanes, along with live load placement in the longitudinal direction of the design lane to maximize extreme effects. Both axle-based and wheel-based vehicle definitions that model the length and width of the vehicle can be used.

Supported Codes

LARSA 4D provides tools that can be applied to any live load design code, including AASHTO LRFD, AASHTO LFD, BS5400, and Indian Roads Congress. The vehicle load patterns for these codes come preloaded in LARSA 4D, and additional as well as custom vehicle load patterns can be entered.

Unique Features

Unique to LARSA’s live load analysis, centrifugal force factors can be specified which automatically adjust wheel magnitudes. Multiple factors can be specified to apply difference factors on the different segments within a single influence surface, and surface design lanes can include UDL without vehicle loading to promote flexibility in creating load combinations.

LARSA 4D Influence Surface Analysis

Flexible Post-Analysis Capabilities

After an influence surface based analysis is performed, new vehicle definitions can be assigned to capture results without needing to run a new analysis, which is particularly useful when load rating structures.

Flexible Vehicle Library

LARSA 4D allows users to define their own custom vehicles, or select one from LARSA's predefined vehicle library to perform code check and load rating after a live load has been performed.

Live Load for Time History

LARSA can also automatically create time history excitation curves based on vehicle speed to run nonlinear and linear time history analysis and capture dynamic effects.

Influence line and surface based live load analysis is included in the following LARSA 4D BRIDGE SERIES packages.

  • LARSA 4D BRIDGE pLT

    Designed for Steel Girder Bridge Projects

    Learn More
  • LARSA 4D BRIDGE

    Our #1 Software for Bridge Projects

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  • LARSA 4D BRIDGE PLUS

    The complete software for Segmental Bridges

    Learn More

LARSA 4D BRIDGE pLT

LARSA 4D BRIDGE

LARSA 4D BRIDGE PLUS