October 30, 2020

Exclude Results based on Selection in RISAFloor and RISAFoundation

New to RISAFloor and RISAFoundation is the ability to exclude results by selection. Excluding results from your model is useful when there are certain elements whose results aren’t of interest to you. Removing this clutter from the results will enable you to concentrate on the elements you are most interested in.

Tags: RISAFloor, Results, RISAFoundation, New

March 26, 2021 | Seismic, RISA-3D, New, Steel, BRBF

Buckling Restrained Braced (BRB) Frames in RISA-3D

The ability to design buckling restrained braced frames has been added to RISA-3D when you integrate your model from RISAFloor. In collaboration with CoreBrace, this new feature came as part of the release of RISA-3D v19.0.0 and RISAFloor v15.0.0. The purpose of buckling restrained braced frames is such that the brace is used as a fuse to dissipate energy during a seismic event. The buckling restrained brace is composed of a steel core and a concrete case. These members are advantageous because the concrete case increases the buckling capacity of the steel core. This enables a more efficient and economical design. The integration of RISAFloor and RISA-3D fits well with the split gravity and lateral design requirements for the BRBF system. The framing members such as columns and beams can be designed in RISAFloor under gravity loads to meet the requirements of them resisting gravity loads without BRB braces. After the model is directed to RISA-3D, users can add BRB braces to perform the lateral load design for the whole system. The buckling restrained braces can be accessed and assigned through the Hot Rolled Steel shape database by selecting the CoreBrace from the Database dropdown menu and selecting BRB as…

March 26, 2021 | Seismic, RISA-3D, New

Capacity Limited Design in RISA-3D

With the release of RISA-3D v19.0.2, you can now design special concentrically braced frames (SCBF) as well as buckling restrained braced frames (BRBF) according to the capacity-limited design. The objective of capacity-limited design is to ensure columns and beams in braced frames are designed to resist the capacity-limited seismic load effect based on brace expected strengths. The steps below illustrate the workflow for SCBF capacity-limited design in RISA-3D. For more information regarding design of BRBF in RISAFloor and RISA-3D, please refer to the following article: Available codes for the capacity-limited design of members include: AISC 360-10 (AISC 341-10) AISC 360-16 (AISC 341-16) If AISC 341-10 is selected, the members will be designed for the lesser of the capacity-limited and overstrength load combinations. If AISC 341-16 is selected, the envelope load combination will be used for design. Whether you’re integrating your model from RISAFloor or if you’re creating your model natively in RISA-3D, you will need to be sure to assign the proper seismic design rules to your members for capacity-limited load combinations to be considered. You can define your seismic design rules in the Seismic Design Rules spreadsheet, and assign the defined rules to members within the Properties Panel under…

April 22, 2025 | New, Structural Engineering

Reinforced vs. Post-Tensioned Concrete: Which One Fits Your Project?

When designing a concrete structure, engineers must decide between conventionally reinforced concrete and post-tensioned (PT) concrete. This choice impacts the structure’s efficiency, cost, and long-term performance. Each system has unique mechanical behaviors and design considerations that influence their suitability for different applications. Selecting the appropriate system requires a thorough understanding of load paths, material behavior, and construction constraints. Reinforced Concrete: Mechanics and Applications Reinforced concrete relies on mild steel rebar embedded within the concrete to resist tensile forces. Concrete performs well in compression but is weak in tension, necessitating reinforcement to manage the tensile stresses induced by bending and shear forces. The steel reinforcement acts as a tensile load path, ensuring structural integrity and limiting excessive deformation. Structural Behavior and Design Considerations Load Transfer Mechanism: In reinforced concrete, loads generate bending moments that cause tensile stresses. These stresses are resisted by well-placed reinforcement, primarily in the tension zones. Cracking and Long-Term Durability: As concrete undergoes shrinkage and thermal expansion, cracks inevitably develop. Proper detailing, including adequate reinforcement ratios and spacing, mitigates these effects and enhances durability. Deflection and Serviceability: Reinforced concrete members often require increased section depth to control deflection, which influences architectural and spatial design constraints. The stiffness of…