GT STRUDL is used by industrial organizations, construction firms, heavy and light industry design firms, power industry design firms, utilities and manufacturing companies, governmental agencies, and educational institutions for the frame and finite element static, dynamic, and nonlinear analysis and the structural design of a wide variety of structure types including but not limited to :

• Process plants and industrial structures of all kinds
• Commercial and residential low and high rise building structures
• Long span roof support systems
• Large tower structures including power transmission and communication structures
• Bridge structures including cable stayed, suspension, arch, truss, plate girder, and prestressed concrete
• Power plant structures such as pipe support systems, cable trays, generator pedestals, platforms, nuclear containment structures, and pressure vessels
• Massive hydraulic structures such as locks, dams, tainter, and miter gates
• Civil works structures such as reservoir and flood control dams, culverts, bridges, transportation facilities, and others
• Offshore platforms
• Radar dishes and their supporting structures
• Pipe intersection analysis for stress- index/ stress- intensity determination
• Manufacturing machinery and manufactured component parts
• Construction and agricultural equipment such as crane booms, loaders, backhoes, earth movers, tillers, and others
• Transportation equipment and component parts such as automobile and truck frames and bodies, railroad cars and connectors, aircraft wings and fuselages, ship structures, and others
• Dock and shore structures

The problem solving requirements of engineers are communicated to GT STRUDL through a standard Microsoft Windows menu-driven and graphical user interface In addition, GT STRUDL offers a structural engineering command interface as a compliment to its powerful interactive graphical modeling features. Engineers can retain and exercise control over all processing facilities to the extent required to meet engineer-defined needs, rather than merely inputting data to a predefined computer process.

GTMenu is a graphical user interface within GT STRUDL that is designed for the generation, display, and changing of structural model data. Some of the major features of GTMenu are as follows:

Unlike any other structural design and analysis system, GT STRUDL maintains a comprehensive structural database which contains problemdescription characteristics specified by the engineer, as well as results generated as a consequence of one or more analyses and/or design processes. The engineer may save, restore, display, update, correct, add, delete, activate, or inactivate any information in the problem database. This unique feature provides the engineer with significant time savings in the iterative structural analysis/design/ decision-making process wherein the computer stores, processes, and displays information upon request, while the engineer exercises decision-making responsibilities. Engineers can make requests for information "on the fly", rather than having to make decisions about what output they will want while defining the problem.

GT STRUDL contains a large library of member and finite element types consisting of 7 member types (constant or variable cross-section), over 100 conventional, isoparametric, and hybrid formulation finite element types, and many special transition elements including:

• Plane truss / frame / grid and space truss / frame members.
• Curved plane and space frame member element including internal pressure effects.
• Plate bending elements to model thin to moderately thick plates (3, 4, and 8 node triangles and quadrilaterals).
• 3-D solids (6 to 20 node triangular prisms and straight and curved edge bricks).
• Thin shell elements (3 and 4 node triangles and quadrilaterals with 5 or 6 degrees-of-freedom per node).
• Axisymmetric elements (4 to 8 node quadrilaterals) for modeling solids of revolution.
• Large library of special transition elements for plane stress, plane strain, Axisymmetric stress (4 to 8 node quadrilaterals) and 3-D solid (8 to 20 node bricks) problems.
• Special finite element for modeling shear walls and floor slabs where a rotational degree-of-freedom is provided about an axis normal to the element in order to allow coupling of member rotational degrees-of-freedom with the element (e.g., beam bending may now be coupled with a shear wall).
• Multilevel superelements (i.e., sub-structures defined from user specified collections of members, finite elements, and other superelements) may be defined for large and complex linear static analysis problems.

• Structures may be composed of any combination of member and/or finite element types whether they have the same or different type and number of displacement degrees-of-freedom per node.
• Only the minimum number of relevant displacement degrees-of-freedom are automatically used by GT STRUDL in the analysis of a structure resulting in significant analysis cost reduction.

Member element properties include :

• Prismatic and variable section member property input including cross-section area, shear areas, torsion constant, bending moments of inertia, section moduli, cross-section dimensions, location of shear center, and others.
• Prestored table specification of member properties including wide flange, channel, tee, single and double angle, pipe, tube, round and rectangular solid bar, and other shapes.
• Further, users may specify member properties by giving a flexibility or stiffness matrix.

• Element type and thickness for isotropic elements.
• Element rigidity matrix input for orthotropic or anisotropic material properties.
• Order of numerical integration for certain elements for better control of accuracy and efficiency.

• One or any valid combination of the six general force boundary conditions at one or both ends of a member.
• Linear elastic flexible member boundary condition connections to structure joints (i.e., up to twelve (12) translation and rotation springs may be modeled between the ends of members and joints).
• Rigid joint size and rigid links using member eccentricities and end joint sizes.
• Any combination of end joint size and end eccentricity conditions at one or both ends of a member.

• One or any valid combination of the six general force and/or kinematic boundary conditions at a support joint.
• Support restraint directions which may be parallel or non- parallel (rotated) to the global reference frame.
• One or any valid combination of the six translation and rotation linear elastic or nonlinear spring supports at support joints which may be parallel or non-parallel (rotated) to the global reference frame.
• Automatic location and processing of planar joints.

• Describe many joint degree-of-freedom constraints and master-slave relations.
• Joint "tie" for equality of displacements.
• Rigid pin, rigid plane, rigid plate, and rigid solid definitions for modeling rigid body structural behavior.
• High-rise building analysis using mathematically rigorous rigid body floor modeling techniques.

An unlimited number of independent static loading conditions may be composed of any combination of seven loading types, which are:

• Joint loads (forces and moments).
• Joint displacements (translation and rotation).
• Member loads (concentrated and uniformly and linearly distributed forces and moments in the local, global, or projected global coordinate systems).
• Member temperature loads (axial and bending).
• Member distortions (fabrication errors and up to six (6) generalized initial strains).
• Joint temperature loads for finite element temperature variations (in-plane stretching and bending).
• Element loads. (edge, surface, and body forces in the local, planar, global, or projected global coordinate systems).

• Member dead loads generated as uniformly distributed member loads and/or equivalent joint loads, and including dead load factors.
• Finite element dead loads generated from element body force specification.
• Moving load generator may be used to define standard AASHTO highway vehicles or user defined trains of moving loads over any contiguous line of members in a structure as independent static loading conditions.
• Independent loading condition cases may be formed as a combination of the specifications of other independent and dependent loading condition cases.
• Dynamic joint loads include acceleration, velocity, or displacement time history and harmonic variations.
• Dynamic response spectra (acceleration, velocity, displacement vs. frequency, period) for multiple damping values may be input and stored for future reference or may be selected from prestored earthquake spectra.
• Pseudo static load cases may be formed from earthquake response spectra analysis results for standard loading condition processing such as combining with static analysis load case results.
• An unlimited number of load combinations (Dependent Loadings) may be formed with user-defined combination factors.
• Any combination of independent and/ or other dependent static and/or pseudo static load cases may be formed by an Algebraic summation of results, or by using an RMS or ABS (absolute sum) combination.
• General recursive load specification error detection.
• Dependent load results may be computed during any stiffness analysis, or at any time subsequent to one or more stiffness analyses.

• Linear elastic material properties may be specified, including Young's modulus (E), shear modulus (G), Poisson's ratio, coefficient of thermal expansion (CTE), and Weight Density.
• Different members and/or elements may have different material properties.
• Implicit specification of material properties for members and finite elements identified as steel, aluminum, or concrete.
• User specified BETA angles for local member coordinate system axis orientation.
• Automatic computation of BETA angles from user specified BETA reference planes (i.e., 3rd-point BETA angle specification).

• Units of length, force, angle, temperature, and time may be changed by the user at any point, and as often as the engineer desires for both problem description data and result output data.
• Both the English system and SI system of units may be used entirely interchangeably throughout a GT STRUDL execution.

UNMATCHED SOFTWARE RELIABILITY AND USER SERVICES

GT STRUDLis a fully supported application software product which is intensively maintained and continuously researched and developed in order to provide the engineering profession with the most reliable and the latest advances in structural engineering analysis and design computer software. Support is provided by the Computer-Aided Structural Engineering (CASE) Center, Georgia Institute of Technology, Atlanta, Georgia, USA. The CASE Center is staffed by a large team of full-time research engineers and scientists with broad and long-term experience in structural theory, engineering mechanics, structural design, computer science, and professional engineering practice.

GT STRUDL support and quality assurance standards offered by the Georgia Tech - CASE Center are among the most rigorous in the industry. GT STRUDL software certification procedures are in full conformance with the applicable provisions of the U.S. Nuclear Regulatory Commission quality assurance and quality control regulations (10CFR-50, Appendix B), and ISO9000-3. Full-service support provided by the CASE Center includes software verification and certification, quality control and assurance, program updates, enhancements, performance improvements, and telephone hot- line support (providing installation assistance, systems support, and advice on the effective uses of GT STRUDL).

Final quality assurance and validation testing is currently underway for the next version of GTSTRUDL which is targeted for release during August 2000. A decision has been made to change the version number designations for GTSTRUDL. The next version will be called Version "25.0" (i.e., GTSTRUDL 25.0) in celebration of the 25th anniversary of developing and supporting GTSTRUDL worldwide.

Among other new features and error corrections, GTSTRUDL 25.0 will include the following important, powerful, and cost saving features 

• The EC3 limit state steel design code
• The Canadian limit state steel design code
• Plate girder steel design by the AISC LRFD code
• Member cross-section area properties, and steel design code check requirements, may be computed from input cross-section dimensions for I-shape, plate girder, and pipe sections
• Nonlinear plastic hinge Push-Over Analysis for frame structures
• Nonlinear member end boundary springs
• Additional dialogs and menu options in the GTSTRUDL text output window such as:
  • Graphical display rotation using arrow keys or cursor, including "solid display" while rotating
  • Graphical display rotation "tumbling"
  • Set arrow keys expanded to include rotation increments
  • Digitizing grid for creating and editing frame and finite element models
  • Finite element analysis energy and stress error estimates may be contoured
  • Steel design unity checks and pass/fail information can be displayed

• Additional GTMenu features including:
  • Groups of data in data sheets may be selected together by using the control key and mouse, or by using the mouse to fence the data groups
  • In the "list dialog box" for menus in the command text and menu interface screen, the names of members, finite elements, groups, and loads may be selected from a displayed list of available names (i.e., the list box will include the ability to specify names of members, finite elements, loading conditions, and groups by using the mouse without the need to type any names)
  • Different User Data Sets may be opened and closed one at a time during an execution of GTSTRUDL
  • Digitizing grid for creating and editing frame and finite element models
  • All current steel design codes can be referenced in the Design/PARAMETERS dialog
  • Nonlinear tension/compression only members may be specified in a menu
  • The ACTIVE/INACTIVE load dialog box will permit groups of load names to be selected by using the control key and mouse, and by fencing the names with the mouse
  • The user may create new user section tables by using a drag and drop feature
  • A new menu feature to create member section properties from the cross-section dimensions
  • Dynamic transient, response spectrum, steady state, and harmonic loads may be specified using menus
  • Dynamic modes may be inactivated, and the net mass participation factors may be displayed, in a menu
  • Dynamic pseudo static loads may be created by using a menu
  • Pushover analysis may be selected
  • OUTPUT FORMAT, and text output of finite element analysis results may be requested by menu picks

• Other very useful and powerful features