FATIGUE LIMIT STATE
FEA Finite Elements Analysis, Static Analysis, Linear and Nonlinear Analysis, P-Delta Analysis, Natural Frequency Analysis, Static Equivalent, Seismic and Dynamic Analysis, Time-History Analysis, Modal Analysis, Spatial Objects and Spatial Loads, Buckling Analysis, Spectral Analysis, Advanced Section Stress, Torsion and Warping, Built Up Sections, Catenary Cables, Diaphragm Analysis, Notional Horizontal Loads, Loads and Load Combinations.
Spatial objects are used to model non-structural secondary elements attached to the structure. These elements add no stiffness to the existing model. Loads applied to spatial objects are transferred to the structure through one or more attach joints. The loads are transferred using a “rigid plate” approach.
Concentrated, pressure and wind loads may be applied to spatial objects. The figures below shows a spatial object loaded vertically and horizontally attached to a cantilever column. Also, it shows the deformations and biaxial moments induced by the loads transferred by the spatial object.
The catenary cable element is a highly non-linear element used to model the catenary behavior of a cable suspended between two points under the effect of its self-weight. This formulation accounts for the non-linearity due to large displacements.
A cable has no bending, shear, compression or torsion stiffness. Due to this fact, the fixities at the ends are ignored; the cable is always treated as member acting in tension only. In the interface of the HSE, the user can create a catenary cable by associating a cable type section to a member.
Direct Analysis Method (DAM) available for AISC 360-16 and AISC 360-10 standards. The options for the Stability Design Method are Direct Analysis Method (DAM) and Effective Length Method (kL).
The HSE software considers restrained warping for the torsion of thin-wall open sections. Notice that this phenomenon is not included in most commonly used frame analysis programs. Almost all frame programs in practice use St-Venant torsion theory ignoring the effects of restrained warping.
The SAFI HSE software includes the fatigue limit states.
All fatigue parameters for the structure can be set into the highway sign wizard . The CAFT (Constant Amplitude Fatigue Threshold) or (DF)TH for infinite life for the different fatigue detail categories are found in AASHTO LTS-13 (ASD) Table 220.127.116.11-1 and AASHTO LTS-15 (LRFD) Table 18.104.22.168-1.
The Highway Sign Wizard assigns these values when generating the model according to the input data. If the model has not been generated or after the model generation is done, the user can edit this table to change the fatigue parameters for the connection details for both ends of the member.
The Fatigue load combinations are required to compute the equivalent static forces and stresses range due to cyclic loading. The fatigue resistance is specified in AASHTO LTS-15 LRFD clause 11.9 and AASHTO LTS-13 ASD clause 11.9.
This main option activates the input required for fatigue verification. Depending on the type of structures, the fatigue verifications (Galloping, Natural Wind Gust, Truck-Induced Gust) may be activated or not. The user must check on the applicable fatigue loads according to its type of structure based on the requirements of the AASHTO LTS code.
Natural wind gust stresses result from the inherent variability in the direction and velocity of the wind induced airflow around the structure. Natural wind gusts are the most basic phenomena that may induce cyclic loads in lighting and traffic structures. It is generally applied to cantilevered and non-cantilevered overhead sign and overhead traffic signal supports.
Truck-induced gust loads are caused by the passage of trucks under traffic structures. These gusts of wind are caused by moving trucks and create both horizontal and vertical pressure on the structure. The vertical mast arm vibration results in the most critical stresses and therefore only the vertical pressures are evaluated. It is generally applied to cantilevered and non-cantilevered overhead sign and overhead traffic signal supports.
This wizard allows generating standard and nonstandard highway sign superstructures of type A1. The standard models are based on the typical plans of the Ministry of Transportation of Quebec. These standard structures are always assumed to be made of aluminum tubes.
The required steps for creating such structures are the following:
1 – Parameters
2 – Beam dimensions
3 – Column dimensions
4 – Beam panels
5 – Column panels
6 – Pedestals
7 – End
Local coordinate systems
Linear or circular lines of constructions for model creations
Automated commands for model creation such as move, rotate, extrude, copy, attach, subdivide and others
Models can be edited either graphically or by means of spreadsheets
Element can be created in batch or one by one
Elements of the models can be selected either graphically or according to a set of criterions
Persistent groups of selected objects can be created and edited graphically or by means of spreadsheets
Definition of physical members
Selection and edition of physical members
Definition of loading surfaces
Multiple edition grids with user defined spacing, angles and labels
Powerful edition and automatic generation tools
Members can be subdivided in any number of equal segments or at specific positions
Similar connected members can be merged together
Elements of the structure can be renumbered according to several criterions
Element attributes can be set graphically or by means of spreadsheets (sections, analysis parameters, rotation angles, etc.)
Element attributes can be edited in batch or element by element
Loads can be edited graphically or by means of spreadsheets
Contour lines for finite element plates with customized bounds
Wizard based geometry generation
A large number of pre-defined frames
Circular and parabolic arches
Cylinders and cones composed of beams and/or plates
Physical elements concept to group different elements
Surfaces can be used for load transfer and self-weight calculation
Surfaces can be used to simulate diaphragm effects
Standard sections (CISC, AISC and European)
Custom section libraries
Non-standard sections (over 30 shapes available)
Truss and pre-tensioned cable sections
User defined section properties
Composite sections are available
Metric, imperial and mixed units systems are allowed and can be modified at any time. Reports are printed according to any unit system.
Graphical display of seismic and dynamic analysis results
Model size limited only to the physical capacity of the computer.
Objects transparency for various components such as current selection, solid members, plates, surfaces, spatial objects, panels.
The level of transparency may be customized for each type of object from the Display Options command.
Functionalities of the HSE program allow to generate automatically detail elements in an automatically generated mesh perimeter.
These functionalities are specifically related to the refinement area, the opening, the linear constraint and the punctual constraint.
All detail elements added to the HSE model will be automatically connected to the finite element mesh.
The mesh perimeter will also connect any elements already in the model to the mesh perimeter automatically if they are in the plane of the mesh contour.
The program calculates the bending, compression, tension, shear and combined resistance of aluminum based on the results of a linear, P-Delta, non-linear, seismic, dynamic or moving load analysis. Singly symmetric, asymmetric and built-up section shapes are covered for all design codes.
•Aluminum design codes
• Member Attributes – Aluminum
• Bending Parameters
• Compression and Tension parameters
• Welds parameters
• Redesign selected members
• Design summary
AASHTO LTS-13 (ASD) and AASHTO LTS-15 (LRFD) design standards. The AASHTO LTS-13 (ASD) and AASHTO LTS-15 (LRFD) (Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals) steel design codes are implemented in SAFI HSE (Highway Sign Structures).
The AASHTO LTS-15 (LRFD) (Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals) aluminum design code are implemented in SAFI HSE (Highway Sign Structures).