STRAP: A Sophisticated and User-friendly Structural Analysis Software Designed for All Types of Structures
ATIR has developed STRAP into a sophisticated and user-friendly software that allows engineers to design and analyse many types of structures. It goes far beyond the basics of structural engineering analysis as it includes complex technical functions suitable for nearly all types of structures, such as the use of submodels, the design for multiple construction stages, and tools for efficient project management. We will explore the many types of features that make STRAP one of the industry’s leaders in structural design and analysis.
File Management
When you open STRAP you will see this page.
File Management
When you open STRAP you will see this page.
This page serves as a file management system for your models. It lists your models sorted either by name or by date. You can copy, delete, and compress models into a ZIP file. Moreover, you can make sure that you are selecting the right model by viewing the thumbnail drawing of the model and its statistics (eg. total number of nodes, elements, walls,etc). The"note" option lets you write comments and reminders for each model and to track revisions.
Structural Types
There are several options that you can choose to create a new model. You start by selectinga framing option (plane frame, plane grid, space frame or truss), thenopen a blank template or choose from predefined structural models in the Model Wizard option.
Structural Types
There are several options that you can choose to create a new model. You start by selectinga framing option (plane frame, plane grid, space frame or truss), thenopen a blank template or choose from predefined structural models in the Model Wizard option.
We will try the "Truss on Columns" Model Wizard. Once this option is selected, STRAP guides you through the model definition process by asking for therelevant dimensions - column height, truss height, the camber at the center, etc. STRAP then asks for your section material properties and sizes, as well as your vertical loads and wind loads. For this example, we will assume the dead load to be 24 kN/m (3.0 kPaDL x 8m load width) for both the top and bottom chord to account for services and ceiling loads. A live load of 16 kN/m (2.0 kPa LL x 8m load width) will be assumed for maintenance loads. For wind loads, it isconservatively assumed that wind pressure is qz = 2.3. Wind load on roof and columns is qz x -1.4 x 8m = -26kN/m (windward) and -15 kN/m (leeward). Wind load parallel to ridge is qz x -1.0 x 8m= -18kN/m. All these values can be revised later.
Nodes and Restraints
Once you are in the model, you can view the Geometry Menu at the far right. The first menu item is the "Node"option. Here you can define a single node or several nodes lying on a line with equal or varying spacing. Unlike some commercial software out there, you can renumber your node numbers, which allows you to present your models in a much more organized manner. Remember to output your data again after renumbering your nodes!
In the "Restraint" option you can define restrained degrees of freedom (translation or rotation in different directions) at each node.
Elements
To define or revise beam elements, select the "Beam" option. You can create single beams, a continuous straight line of beams, an arc of beams, or a string of beams. You can also use the Beam option to change section properties by selecting sections from predefined steel tables, or combining sections to create composite members. You can also input your own material properties (modulus of elasticity, Poisson ratio, density, etc). End releases can be defined at the beam ends. Even non-linear end releases or plastic hinges at beam ends can be input. Not a lot of software has this sophisticated function, as they often only provide only basic linear end release options.
Once you are in the model, you can view the Geometry Menu at the far right. The first menu item is the "Node"option. Here you can define a single node or several nodes lying on a line with equal or varying spacing. Unlike some commercial software out there, you can renumber your node numbers, which allows you to present your models in a much more organized manner. Remember to output your data again after renumbering your nodes!
In the "Restraint" option you can define restrained degrees of freedom (translation or rotation in different directions) at each node.
Elements
To define or revise beam elements, select the "Beam" option. You can create single beams, a continuous straight line of beams, an arc of beams, or a string of beams. You can also use the Beam option to change section properties by selecting sections from predefined steel tables, or combining sections to create composite members. You can also input your own material properties (modulus of elasticity, Poisson ratio, density, etc). End releases can be defined at the beam ends. Even non-linear end releases or plastic hinges at beam ends can be input. Not a lot of software has this sophisticated function, as they often only provide only basic linear end release options.
You can also create plate elements by defining triangles, parallelogram and quadrilaterals. The "mesh" option automatically fills a large area with elements. Plate elements can be of uniform or tapered thicknesses.
Unidirectional springs or elastic supports can be defined. These can be used to model soil coefficients for the design of ground beams or mat foundations. STRAP also goes one step beyond typical commercial programs by including the option to design with non-linear springs and gap elements, which are often used for analyzing soil and structure interaction during seismic activities.
Unidirectional springs or elastic supports can be defined. These can be used to model soil coefficients for the design of ground beams or mat foundations. STRAP also goes one step beyond typical commercial programs by including the option to design with non-linear springs and gap elements, which are often used for analyzing soil and structure interaction during seismic activities.
STRAP also provides options to create solid elements by lifting and rotating plate elements.One unique function that STRAP has is the ability to create atypical walls shapes. In the Wall section editor, walls with openings can be created, as well as walls with multiple segments. Wall sections can also be retrieved from an existing DXF file.
Sbmodels
One of STRAP’s key features is the use of "submodels". Submodels are a small part of the complete model and are defined in a different working area. The submodels are then attached to the "main model" to form the complete structure.
Submodels are useful when there is a repetitive part of the model. The submodel can be attached multiple times to the main model; each one is referred to as an "instance" of the submodel. There are options to define the location and type of connection between the submodel and the main model.
There are a lot of advantages to this feature.
One of STRAP’s key features is the use of "submodels". Submodels are a small part of the complete model and are defined in a different working area. The submodels are then attached to the "main model" to form the complete structure.
Submodels are useful when there is a repetitive part of the model. The submodel can be attached multiple times to the main model; each one is referred to as an "instance" of the submodel. There are options to define the location and type of connection between the submodel and the main model.
There are a lot of advantages to this feature.
- Submodels are great for designing typical floors in high-rise buildings. If you want to change properties or loads within a typical floor, you can revise thesubmodel and all the revisions are automatically applied in all the instances.
- Each submodel can contain the program capacity for nodes and elements. The maximum model size becomes limitless when submodels are defined.
- The analysis time is reduced when submodels are used.
- The nodes and elements arenumbered independentlyin submodels. Main model and submodel results are displayed separately.
STRAP then automatically determines the "connection points" where the submodel is attached to the main model; it searches for the submodel nodes and main model nodes that are closest to each other. If the connection nodes cannot be unified (ie. do not share the same coordinates), a rigid link between the connection point and main model node will be created.
Stages
Different construction stages of model can be designed. In typical structural engineering software, you must design the whole model which represents the final structure at the end of construction. However in STRAP you can easily and rapidly design different construction stages by basing new stages on an existing stage. Each stage can have different sections, supports and, most importantly, different construction load cases and temporary wind cases. You can use the Stage function to analyze the stability of each separate construction stage and to keep track of the changes, hence increasing safetyfor each stage.
Stages
Different construction stages of model can be designed. In typical structural engineering software, you must design the whole model which represents the final structure at the end of construction. However in STRAP you can easily and rapidly design different construction stages by basing new stages on an existing stage. Each stage can have different sections, supports and, most importantly, different construction load cases and temporary wind cases. You can use the Stage function to analyze the stability of each separate construction stage and to keep track of the changes, hence increasing safetyfor each stage.
Loads
Not only can you input the basic uniformand concentrated loads on beam elements and uniform pressures on elements, you can also input other specialized load cases in STRAP. You can define temperature loads to model the expansion or contraction effects at beam ends or a temperature gradient caused by the contraction/expansion of the width of the beam or element. Here are some other loads that can be input in STRAP:
Not only can you input the basic uniformand concentrated loads on beam elements and uniform pressures on elements, you can also input other specialized load cases in STRAP. You can define temperature loads to model the expansion or contraction effects at beam ends or a temperature gradient caused by the contraction/expansion of the width of the beam or element. Here are some other loads that can be input in STRAP:
- Prestress forces:
- Lack-of-fit effects (when a beam that is initially too short or too long and is made to fit the design length)
- Chess loads or Staggered loads (automatic output of load combination patterns)
- P-Delta loads (non-linear secondary forces which cause iterative calculations)
After your load cases have been defined you can either create your load combinations by typing in the load factors manually or by retrieving combinations from the program’s library.
Calculations and Results
After analysis, STRAP can calculate the following:
Calculations and Results
After analysis, STRAP can calculate the following:
- Elastic slab deflections
- Punching shear stresses in slab elements at column locations: The program will output the effective shear forces, punching shear stresses, concrete capacities or punching shear capacities, and reinforcement needed to resist punching. It also shows graphically whether additional reinforcement is required or whether shear stresses exceed the allowable stress.
- Crack width: STRAP calculates the reinforcement size and spacing required for crack width requirements.
In addition, graphical results for beams and elements can be printed out for documentation and presentation to government officials and clients. Element results can be displayed with a contour maps, or with values plotted along a section line drawn through the model.
Other Modules
There are other modules that you can explore and use in STRAP.
Have a go at STRAP!
Download their trial version today!
This post is sponsored by ATIR.
Other Modules
There are other modules that you can explore and use in STRAP.
- Dynamic Analysis:
This module analyzes structural behaviour under dynamic loads and solves for mode shapes. - Seismic Design:
Seismic load cases can be produced by specifying seismic factors and scaling.
- Structural Steel Design:
You can use this module to check sections or select the optimal steel sections, according to specified properties and conditions. You can also display detailed results and calculations of your design checks (moment diagrams, section properties, section classification, shear, moment, axial, deflection, lateral torsional buckling and combined stresses).
- Concrete Module:
This module designs reinforced concrete beams, columns, walls, and slabs and their reinforcement and deflection results. Reinforcement drawings can also be generated.
- AutoSTRAP:
This program generates the structural model from an DXF drawing.
- POSTTEN:
This module designs post-tensioned concrete beams and slabs.
Have a go at STRAP!
Download their trial version today!
This post is sponsored by ATIR.
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