When you open STRAP you will see this page.
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.
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.
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.
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.
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.
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.
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)
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.
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.
This program generates the structural model from an DXF drawing.
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.