The applied loads in a response spectrum analysis (RSA) are the applied masses times the accelerations in the response spectra. Each mode of vibration produces its own set of joint reactions. The reactions for each mode obey statics as shown in the portal frame example shown below: Response...
In order to get code calculations, RISA-3D and RISA-2D need to know what type of shape would be most similar to yours. This is because the program needs to use the correct code equations for your shape type.
Investigating P-Delta instabilities in RISA-3D (or RISA-2D) can be difficult. The first step is usually to solve the model without the P-Delta effect included to see if there are any obvious deflection problems that could cause issues with a P-Delta analysis. But, what can be done when this doesn’t...
RISA-3D, RISA-2D and RISAFloor have the capability to project distributed and area loads onto members. Consider the case of snow load on two buildings: one with a flat roof and one with a sloped roof. Ignoring the concept of shedding, if both buildings have the same footprint then they should both...
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:
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.
When your RISA-3D model is not behaving as you anticipated, one of the best tools you have is viewing the deflected shape. Displaying the deflection graphically will help you visualize how the model is behaving and will often times bring to light modeling errors.
In RISA-3D, there are numerous options for Member End Releases which should not be confused with Boundary Conditions.
When you have a plate model for a slab or wall in RISA-3D, the Internal Force Summation Tool (IFST) is a very useful analysis tool to get exactly the forces that you want to design for. To use the tool, you must:
