
May 24, 2011
How to Apply a Tapered Load to Plates in RISA-3D
It’s easy to apply tapered surface loads to plates in RISA-3D by stepping up the loads from one level to the next.
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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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...
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.
After solving a model with Member Area Loads, RISA-3D will automatically create Transient Basic Load Cases that allow the user to verify load distribution.
RISA-3D will now check your model for errors by summing the reactions in your model and comparing them to the applied loads. This occurs for the global X, Y, and Z directions. If RISA identifies that the reactions do not equal the applied loads then the software will show a warning message to the...
In RISA-3D, there are many different applications that require you to define Member Type in your model including AISC 15th Edition steel design, Seismic Design, Concrete design, and models that will be transferred to Autodesk Revit.
V-Brace frames in RISA-3D seismic design have unbalanced forces shown on both the beams and braces. As brace frames displace under lateral loads, one brace will buckle and its force decreases while the other brace in tension will have an increase of force until it reaches yield.
The bending and axial code checks for single angles differ somewhat from other shape types, because single angles behave quite differently in bending and compression depending on how they are braced along their length.
The Seismic Provisions in RISA-3D will check various design and code check requirements according to the AISC design provisions (AISC 360-2005, AISC 341-2005, AISC 358-2009). Seismic Design Rules can be applied to any member in the model, just follow the steps listed below.
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