Steel Bridges

Abstract: 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 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.

The structural analysis is performed via a series of modular subroutines based on the stiffness method. An extensive mesh generation capability incorporates the fully automated AASHTO Dead Load (DL) and Live Load (LL) sequences. The Merlin-DASH system incorporates the most general and widest ranges of capabilities, such as those summarized in the following table.

Summary of Features for Merlin-DASH

System Features

  • Menu-driven input/edit
  • Discrete HELP screens
  • User-selected output
  • Indexed 8½” x 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 operating system for single user or Network version

Analysis

  • 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

Loadings

  • 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