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Steel Framed Structure using STAAD Pro and ROBOT Software

Structural steel is a material used for steel construction, which is formed with a specific shape following certain standards of chemical composition and strength. They can also be defined as hot rolled products, with a cross-section of special forms like angles, channels, and beams/joints.


Different new techniques which enable the production of a wide range of structures and shapes are:

  • High-precision stress analysis

  • Computerized stress analysis

  • Innovative jointing

Types of structural steel sections are:

  • Beams

  • Channels

  • Angles

  • Flats

Advantages of steel structure:

  • Elasticity

  • Ductility

  • Toughness

  • Scope for additions to the existing structure


The steel frame is a building technique with a skeleton frame of vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the floors, roof, and walls of a building which are all attached to the frame.


STAAD Pro

STAAD- STRUCTURAL AIDED ANALYSIS AND DESIGN was developed by Research Engineers International in Yorba Linda, CA and was sold to Bentley systems in late 2005. STAAD. Pro is the most popular software to analyze & design software packages for structural engineering used in performing the analysis & design of a wide variety of structures through its flexible Modeling environment, advanced features & fluent data collaboration. STAAD.Pro may be utilized for analyzing and designing practically all types of structures – buildings, bridges, towers, transportation, industrial and utility structures.


Steps using STAAD-PRO

  1. Prepare the input file.

  2. Analyze the input file.

  3. Watch the results and verify them.

  4. Send the analysis result to steel design or concrete design engines for designing purposes.

Robot

Robot software is used to perform autonomous tasks through a set of coded commands or instructions that tell a robot to perform tasks. Some robot software aims at developing intelligent mechanical devices. Common tasks include feedback loops, control, pathfinding, data filtering, and locating. Common features include a fully graphic definition of construction in the graphic editor (loading a DXF file containing construction geometry prepared with a different program is also possible). A possibility of a graphic representation of the designed construction as well as displaying various calculation outcomes (force, displacement, multiple windows work, etc.) calculations of the construction (dimensioning) while designing another construction (multi-threading), carrying out static and dynamic construction analyses, assigning the rod type while creating the construction model, not in standard modules. Composing any type of print (calculation notes, screenshots, print composition, and exporting objects to other programs).


The automation of the design process reduces the time of project completion and increases the competitiveness of a product. Autodesk’s Robot Structural Analysis is one of the tools facilitating the work of designers and constructors. Autodesk Robot Structural Analysis is an integrated graphic application used for modeling, analysis, and dimensioning various construction types. Features include:

  • Construction design

  • Static calculations of a construction

  • Outcomes verification

  • Standardized calculations of construction

  • Gathering documents and elements for calculated and dimensioned constructions


In multi-story buildings, articulated nominal connections like beam to beam and beam to column, moment connections like the beam to column, and in continuous frames, bracing connections and column bases are commonly used.


The design code 2010 AISC Specification for Structural Steel Buildings (ANSI/AISC 360-10) was used. The more recent version of the AISC Specification for Structural Steel Buildings (ANSI/AISC 360-10) has been implemented in SCIA Engineer v2013.1.


Dead Loads, Imposed Loads, Wind Load and Seismic Load are considered. The GUI (or user) communicates with the STAAD analysis engine through the STD input file. That input file is a text file consisting of a series of commands which are executed sequentially. The commands contain either instructions or data pertaining to analysis and/or design. The STAAD input file can be created through a text editor or the GUI Modeling facility. In general, any text editor may be utilized to edit/create the STD input file. The GUI Modeling facility creates the input file through an interactive menu-

driven graphics-oriented procedure.


A structure can be defined as an assemblage of elements. STAAD is capable of analyzing and designing structures consisting of a frame, plate/shell, and solid elements. STAAD can analyze various structures like:

  • Space structure

  • Plane structure

  • Truss structure

  • Floor structure

The structure may be generated from the input file or mentioning the coordinates in the GUI. Poisson's ratio (POISS) is used to calculate the shear modulus (commonly known as G) by the formula,

G=0.5 x E/(1+POISS)

If Poisson's ratio is not provided, STAAD will assume a value for this quantity based on the value of E. Coefficient of thermal expansion (ALPHA) is used to calculate the expansion of the members if temperature loads are applied. The temperature unit for temperature load and ALPHA has to be the same.


The concrete members can design cross-sections for

  • For Beams Prismatic (Rectangular & Square) & T-shape

  • For Columns Prismatic (Rectangular, Square, and Circular)

Beam Design: All active beam loadings are prescanned to identify the critical load cases at different sections of the beams. As per IS: 13920 the width of the member shall not be less than 200mm and the member shall preferably have a width-to-depth ratio of more than 0.3.


Design for Flexure: The design procedure is the same as that for IS 456. As per IS-13920, the following are considered while designing:

  • The minimum grade of concrete shall preferably be M20.

  • Steel reinforcements of grade Fe415 or less only shall be used.

  • The minimum tension-steel ratio on any face, at any section, is given by:

The maximum steel ratio on any face, at any section, is given by ρmax = 0.025.

  • The positive steel ratio at a joint face must be at least equal to half the negative steel at that face.

  •  The steel provided at each of the top and bottom faces, at any section, shall at least be equal to one-fourth of the maximum negative moment steel provided at the face of either joint.

Design for Shear: The shear force to be resisted by vertical hoops is guided by the IS 13920:1993 revision. Elastic sagging and hogging moments of resistance of the beam section at ends are considered while calculating shear force. Plastic sagging and hogging moments of resistance can also be considered for shear design if the PLASTIC parameter is mentioned in the input file. Shear reinforcement is calculated to resist both shear forces and torsional moments.


Column Design: As per IS 456:2000, columns are designed for axial forces and

biaxial moments. Columns are also designed for shear forces. All major criteria for selecting longitudinal and transverse reinforcement as stipulated by IS: 456 have been taken care of in the column design of STAAD.


Design Operations: STAAD contains a broad set of facilities for designing structural members as individual components of an analyzed structure. The member design facilities provide the user with the ability to carry out a number of different design operations.

The operations to perform a design are:

  • Specify the members and the load cases to be considered in the design.

  • Specify whether to perform code checking or member selection.

  • Specify design parameter values, if different from the default values.

  • Specify whether to perform member selection by optimization.

These may be repeated any number of times depending upon the design requirements.

Earthquake motion often induces force large enough to cause inelastic deformations in the structure. If the structure is brittle, sudden failure could occur. But if the structure is made to behave ductile, it will be able to sustain the earthquake effects better with some deflection larger than the yield deflection by absorption of energy. Therefore ductility is also required as an essential element for safety from sudden collapse during severe shocks. STAAD has the capabilities of performing concrete design as per IS 13920. While designing it satisfies all provisions of IS 456 – 2000 and IS 13920 for beams and columns.


Autodesk Robot Structural Analysis Professional API

Autodesk Robot Structural Analysis Professional software offers full access to an open API. Robot Structural Analysis Professional API exposes the standard functionality of Robot, facilitating programmatic control through external software. Access to robots through this mechanism can enable any routine tasks or processes accessible through the standard user interface to be fully automated and, thus, more rapidly repeatable, extendible, and scalable. With help from Robot Structural Analysis Professional API, users can drive their analysis model for a number of tasks, including creating complex models; generating and modifying geometry/mesh; applying and editing material properties, sectional information, and boundary conditions; and running analyses and extracting results. Programmatic access can enable the execution and control of the analysis tasks so multiple design options can be more quickly evaluated while also testing for design compliance.


Automation of Design Processes:

  1. Geometry generation and manipulation( Eg: node coordinates)

  2. Mesh generation (Eg: Mesh size)

  3. Assignment of structural material and sectional properties (Eg: section database, material stiffness)

  4. Analysis run (Eg: nonlinear) and results evaluation

  5. Iteration through the above four steps until design criteria are met

The Robot Structural Analysis Professional API enables programmatic control of each of the above processes, helping provide rapid reduction in each design iteration time. The open API enables real customization of the design processes by integrating Robot with proprietary CAD packages, post-processing software, or bespoke tools developed as a plug-in to the Robot interface. The API uses Microsoft’s component object model (COM) technology. This means the user can develop simple Visual Basic® for Applications (VBA) code from within applications such as Excel, Microsoft® Word, AutoCAD® software, or develop sophisticated .Net applications to link Robot analysis software with external software. The benefits of automation are numerous.

  • Reduce design time

  • Increase accuracy

  • Increase efficiency

  • Eliminate arduous, repetitive tasks

  • Support rapid design exploration

Optimization Targets, Constraints, and Variables may include minimizing stress, deflection, weight, cost, embodied energy, and maximizing the repetition of components. These need to be met within a framework of other conflicting architectural, engineering, fabrication, and client constraints.


Optimization Techniques: Some of the mathematical and numerical

techniques for optimization are:

  • Simple Newton Raphson techniques

  • Dynamic relaxation

  • Genetic algorithm

  • Simulated annealing

  • Hill climbing methods

When applying these optimizations techniques to real design projects, the emphasis must be on practical, constructible solutions. Thus, need to find out how novel, but practical, tools can be developed and integrated into established design processes and existing software practices.


Analysis Automation and Design Optimization: With a programmable COM interface, the API helps enable automation of the analysis. Using this capability, one can more easily write a program that automatically:

  • Re-creates the geometry and mesh parametrically

  • Applies the sizing and material properties to the mesh elements

  • Runs the analysis

  • Interrogates the results

  • Reports the results, for example, forces schedules in a table or a drawing.

Procedure set up for automated analysis: The integration of Robot Structural Analysis Professional with a powerful BIM application, such as an Autodesk®Revit® product, helps to further benefits including direct linking


Analysis of Steel Framed Building Using STAAD.Pro

Generation of member property can be done in STAAD. Pro. The member section is selected and the dimensions have been specified. The beams are having a dimension of 0.5 * 0.3 m and the columns are having a dimension of 0.8 * 0.8 m on the ground floor and at the other top floors they are having a dimension of 0.5 * 0.5 m. The base supports of the structure were assigned as fixed. The supports were generated using the STAAD.Pro support generator.


The materials for the structure were specified as concrete with their various constants as per the standard IS code of practice.


Steel design of the structure:




Analysis of Steel Framed Building Using Robot


  1. Dead load consideration (Robot) Properties:

3D steel-framed building


2.. Code verification according to ANSI/AISC 360-10:

Steel design of the structure:




Analysis of the Structure using ROBOT

Jardim-Goncalves and Grilo [2010] stated that: Software companies are now developing suites of modeling and construction-related software tools that are interoperable, but they tend only to address interoperability among themselves and not in relation to other vendors’ applications. Using Robot Structural Analysis for engineer calculations of beam-to-column connection type allowed us to evaluate bolted connection resistance, calculation of weld stress, and verification of column web stability. All the outcomes were verified. They are fully compliant with the design and are resistant enough to the forces and moments. Using computer software, through automation, substantially increased the pace of work both while drawing the project and analyzing the data. Also, information about compliance with the norm and fulfilling the assumed endurance conditions was obtained.




**The content of this article is taken from web open source. The blogs are intended only to give technical knowledge to young engineers. Any engineering calculators, technical equations and write ups are only for reference and educational purpose.

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