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Frequently Asked Questions (FAQ)
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AnswerIn the ASCE 7-16, the conservative value for the Gust-factor, G, is 0.85 for rigid buildings. The engineer can calculate an alternative and more accurate value. The Gust-effect, Gf, for flexible buildings accounts for size and gust size similar to rigid buildings but also considers dynamic amplification including wind speed, natural frequency, and damping ratio.The Gust-factor G or Gf, is considered to be 1.0 in RWIND Simulation. The structure is rigidly simulated in the numerical wind tunnel. The loads which are transferred back into RFEM are applied to the elastic structure with true stiffness considered.To account for any value other than 1.0 for this factor, the wind load case factor can be adjusted in RFEM under the applicable load combination.
Additional standards and codes to generate the wind profile automatically in RWIND Simulation will be added in the future. We are always considering feedback from our current customers on which standards will be beneficial.
AnswerThe internal pressure coefficients do not need to be considered with in the RWIND Simulation program.RWIND Simulation always outputs the net pressure on the surfaces in RFEM. When it comes to a simulation with a building that has open windows in RWIND Simulation, there is an internal pressure acting on the inside of the building. The program uses this information to determine the resulting pressure based on the external and internal surfaces. This can be seen in Figure 1.A comparison cannot be made between this coefficient in the standard and a CFD calculation because there is no direct correlation.
You can control the detail categories in the input dialog box "1.3 Cross-Section" and in the "Edit Detail Categories" dialog box.The specified standard values can be selected here. Unfortunately, it is not possible to manually adjust these values.
AnswerIn SHAPE-MASSIVE, the reinforced concrete design has to be activated in the General Data section. As soon as the design is active, it is possible to set the design accordingly in a separate tab (Figure 01).There are three types for the design:Strain-Stress Distribution (Example 01):It is possible to determine an available design ratio by specifying the internal forcesExisting Safety (Example 02):There is determined a state of fracture (ratio = 100%) and a safety in relation to it.Design (Example 03):By specifying a maximum and minimum diameter or a minimum and a maximum reinforcement, it is possible to increase the reinforcement within the design.Irrespective of which of the three methods is used, it is necessary to specify the position of the reinforcement and an acting internal force (Figure 02).
AnswerIf stiffeners are welded into the crane runway, the corresponding notch category according to EN 1993-1-9, Table 8.4, detail 7 has to be considered for the fatigue design. This is implemented in CRANEWAY by creating additional stress points at the connection point of the stiffeners to the section. They can be adjusted manually in the settings for the detail categories depending on the geometry of the stiffener.During the fatigue design of the craneway girder, the design of the axial stress range is additionally performed in the newly created stress points for the x-locations on which a stiffener is provided.
AnswerIn the case of long crane runways and many cranes, the large number of load combinations can lead to a long calculation time. The following settings affect the calculation time significantly:
Calculation method for determining the internal forces
The fast calculation type may therefore be useful for the preliminary design.
- Fast calculation (calculation of all load combinations according to the 1st-order analysis, then calculation of the governing load combinations according to second-order analysis for torsional buckling)
- Detailed calculation (calculation of all load combinations according to second-order analysis for torsional buckling)
Maximum target length of the finite elementsThe maximum length of the finite elements generated for the calculation according to the second-order analysis for torsional buckling can be entered within a range of 100 mm to 2500 mm. The calculation time can be increased significantly by the finer division of finite elements.Thus, you should select a reasonable length of the finite elements for an optimized calculation time depending on the structural system. Usually, 8 elements for each girder span are enough to calculate the deformations with a deviation of less than 5% relative to the precise solution.
Number of load combinationsYou can use a reasonable setting of the load increment to control the number of generated load combinations. When entering the load increment, the generated number of crane load positions and load combinations is already displayed in a preview. A small load increment may result in many load combinations that take accordingly more time in the calculation.
In SHAPE-MASSIVE, you can select the 'Design' option for reinforced concrete design.In this case, an area of the possible reinforcement diameters can be defined when entering the reinforcement bars. In this defined area, the program can subsequently design a diameter which is in accordance with the bending design.By specifying the concrete cover, it is possible to check whether the designed reinforcing steel diameter can be inserted, or not.Provided the concrete cover was entered too large resp. the required diameter is too large, you will receive an error message after having started the calculation.
AnswerThe setting of partial safety factors can be done by defining the National Annex of the standard in the General Data. The predefined National Annexes can not be modified, but it is very easy to create a user-defined National Annex.In this case, it is possible to adjust all standard-specific factors.
AnswerIf you want to modify individual elements of an inserted cross-section, you can do this by various methods.
1. Select another cross-section from the cross-section libraryIf you edit the cross-section or select another one, the corresponding elements will change as well. Click the 'Parametric Input' button to modify the specified cross-section properties.This option is especially useful if you want to keep the base geometry and symmetry of the original cross-section. Sheet thicknesses and overall height or width can be adjusted very easily this way.
2. Dividing the section into individual elementsThus, single independent elements are created from the inserted cross-section. Subsequently, they can be edited like normally created elements.This procedure is useful, e.g. if you want to change the base geometry of the original cross-section.
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Wind Simulation & Wind Load Generation
With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
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