Merlin-DASH (New Interface)

Design and Analysis of Straight Steel and Reinforced Concrete Girder Bridge Systems




MERLIN-DASH was developed for use by bridge design engineers who function in a production environment. In order to provide a program which would be applicable nationally, the BEST Center developed MERLIN-DASH to offer the widest range of features and options necessary to meet the demands of universal usage in the analysis, design, and rating of steel and reinforced concrete bridges.

Program Scope

MERLIN-DASH incorporates a flexible sequence of operations initiated with analysis and proceeding, at the user’s option, to perform any or all combinations of the following functions for the AASHTO WSD LFD or LRFD methods:

      1. Analysis — A complete analysis for all AASHTO DL and LL conditions (see ANALYSIS and LOADING in Table 1) with recycling for changes in sections due to design;
      2. Design — Determination of the size of steel structural components based on a user controlled design sequence leading to either minimum cost or weight;
      3. Code Check — Complete and detailed code check of all steel or reinforced concrete beam components which reference specific AASHTO equation numbers and applicable coefficients;
      4. Rating — Detailed inventory and operating rating of all beam components using either the AASHTO live load provisions or special user specified vehicles.
      5. Staging — Dead load pouring sequence stage analysis

Generality also extends into the structural model incorporated within MERLIN-DASH. The structural analysis is performed via a series of modular subroutines based on the stiffness method. An extensive mesh generation capability allows for the incorporation of fully automated AASHTO Dead Load (DL) and Live Load (LL) sequences. Incorporated within the MERLIN-DASH system are the most general and widest ranges of capabilities, such as those summarized in the following table.

dashg1_small dashg2_small

Summary of Features

  • Menu-driven input/edit
  • Discrete HELP screens
  • User-selected output
  • Indexed 8″ by 11″ output
  • Full range of color graphics
  • Diagnostic level output
  • English or S.I. units
  • Output at designated intervals and changes in section
  • Design recycling
  • Numerous code overrides
  • Numerous user options
  • WINDOWS, or WINDOWS/Network environments available


  • Full and detailed analysis, which includes: Section properties, moments, shear, reactions, deflections, camber, stresses, and stress ranges for DL and LL maxima, etc.
  • Up to 10 simple or continuous spans
  • Hinges at any location
  • Linear or parabolic haunches
  • Standard section table look-up
  • Steel standard sections with cover plates
  • Steel plate girders ?stiffened/unstiffened
  • Composite/noncomposite construction
  • Variable composite in negative moment region
  • Different reinforced concrete section types


  • All DL and LL given automatically
  • All AASHTO truck and lane loadings
  • Extended AASHTO to HS99 and HL-93
  • Interstate (military) loading
  • Standard state truck menu
  • User-specified 2-3-axle trucks
  • User-defined 20-axle truck
  • User-predefined truck files
  • Sidewalk LL
  • Overrides on impact and dist. Factor
  • Special DL conditions
  • Staged DL capabilities