
December 16, 2015
Concrete Design per ACI 318-14 Concrete Code now Available
The new ACI 318-14 code has been implemented into RISA-3D v14, RISAFloor v10, and RISAFoundation v8.
We often get asked: “Should I model my foundation as a slab or a spread footing in RISAFoundation?” While both are valid options, they use very different analysis methods, and the results can vary accordingly. In this article, we’ll walk through a side-by-side comparison, using the same modeled conditions to highlight how the results differ — and why. Model Setup To keep things consistent, we modeled a single condition in two ways: once with a spread footing and once with a mat slab. Mat Dimensions: 10' x 10' x 1' Pedestal: 1' x 1' x 2' Loads Applied: 40 k vertical dead load 10 k lateral dead load 15 k lateral wind load 14.79 k concrete self-weight Soil Overburden: Set to 0 for both elements Slab Mesh Size: Refined below default for more detailed results Load Combinations: A basic set used for clarity (see screenshots in RISAFoundation) Analysis Methodology Feature Spread Footing Slab Element Analysis Type Rigid body Finite Element Analysis (FEA) Support Model Single support point Compression-only springs (based on subgrade modulus) Mesh Behavior No submesh Submeshed into smaller plate elements Lever Arm for Lateral Loads Spread Footings: Full pedestal height + full footing thickness Slabs: Full pedestal height…
Read More
The new ACI 318-14 code has been implemented into RISA-3D v14, RISAFloor v10, and RISAFoundation v8.
RISAFloor is a design program in which it takes basic shape criteria about your beam or column members and then selects an optimal size to meet strength and serviceability criteria. However, the program can just as easily perform a design check for an as-built condition by defining specific member...
Have you been in RISAFloor performing a steel product design and noticed an (SP) extension to a joist designation? The following will discuss when the program designs for these special loading conditions.
You may notice discrepancies in the wood design values when comparing RISA with the NDS 2012 and older versions of the code. The American Wood Council updated the wood design values in the Addendum, which supersede the values used in the NDS 2012 and previous versions of the Design Values for Wood...
The beams in a lateral force resisting system, such as a braced frame or moment frame, typically carry a significant axial force. In the example below (with no diaphragms) the beam (M4) carries a significant axial tension.
Revit offers two options for setting the elevation of beams. The way these are used has a significant impact on how those members are round tripped to RISAFloor, so it is important for you to use them correctly. The Level Offsets are available at each end of the beam. They can be modified through...
In the Seismic Loads dialog there is a checkbox for “Include structure weight in base shear”.
RIAFloor designs the gravity system and then integrates with RISA-3D to design the lateral system. Only the lateral members are taken from RISAFloor over to RISA-3D. The loading is automated in this integration so one of the most common questions is: what loads are transferred when switching from...
There are multiple options in RISA-3D and RISAFloor to create a custom shape not available in the program databases. The first, is to utilize RISASection in order to create cross-sections, calculate section properties and import the shape directly into RISA-3D. For more information on integrating...
Our monthly "Structural Moment" newsletter is the best way to keep up with RISA’s product updates, new releases, new features, training events, webinars and more...