
July 19, 2011
How to export a model to DXF
RISAFloor, RISA-3D, and RISAFoundation all allow the user to export a model as a DXF file for use in most major CAD programs.
With the adoption of ASCE 7-22, the concept of a multi-period response spectrum has been added to seismic design requirements. While this provides more accurate hazard representation, it also means engineers need to generate and input additional site-specific data. This quick workflow shows how to gather that data from the ASCE Hazard Tool and use it in RISA’s site parameters table for seismic load generation. Why This Matters for Engineers? Multi-period response spectra reflect more realistic ground motion characteristics and will increasingly be required as jurisdictions adopt ASCE 7-22. By pulling site-specific values directly from the ASCE Hazard Tool, engineers can ensure compliance and avoid unnecessary assumptions. The multi-period approach can result in higher or lower design forces depending on the building’s period and site class, but it always provides more accurate seismic representation than the traditional two-point method. Download the latest versions of RISA that supports ASCE 7-22 below. Step 1: Generate Multi-Period Spectrum Data Go to the ASCE Hazard Tool. Enter your project location (address, coordinates, or site description). Select ASCE 7-22 as the building code. Navigate to the seismic hazard results and download/export the Multi-Period Response Spectrum data. Step 2: Copy Data Points into RISA Open RISA…
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RISAFloor, RISA-3D, and RISAFoundation all allow the user to export a model as a DXF file for use in most major CAD programs.
While RISA-3D (or RISA-2D) does not have an explicit tool to punch a hole in a plate, you can use the following steps to manually model them:
Have you ever received an instability warning when running a three dimensional RISA-3D model? This is because RISA-3D cannot build the stiffness matrix with the configuration you have modeled. In some cases, your model is truly unstable and in others it’s a matter of correctly modeling your...
In RISAFloor on the roof level, you layout only the top chords of the truss and create your slope. These top chords by themselves probably won’t be sufficient enough to get designed in RISAFloor, but, don’t worry, we’ll take care of that in RISA-3D when we model the rest of truss.
Using this method in RISAFloor, we are not actually designing the trusses, but just adding “dummy” bottom and top chords to correctly calculate the loading and help distribute the loads to the walls.
It’s easy to apply tapered surface loads to plates in RISA-3D by stepping up the loads from one level to the next.
In RISA-3D you can automatically apply notional loads to your structure to comply with your steel code (such as AISC 360). Notional loads take into account a building’s actual out-of-plumbness by adding de-stabilizing lateral loads. The AISC 360 recommends either 0.2% or 0.3% of the vertical loads...
When running a truss model in RISA-3D or RISA-2D, it’s quite common to receive an instability warning, but these can be easily resolved by following a few simple rules.
In Aluminum design, the welded areas have a decreased material strength and RISA-3D can assign any material strength to the members based on the Material spreadsheet.
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