April 5, 2018

Seismic Load Consideration for Retaining Walls

RISAFoundation has the capability to consider seismic loading for retaining walls.

Retaining Wall Earthquake Loading1 300x240 2x

The Mononobe-Okabe formulation has been implemented. Though direct input of the maximum pressure at the top of the wall can also be defined to create the inverted triangular loading.

For details on the Coulomb calculations and the variation due to the Seed & Whitman adjustments please check out the Wall Footings – Design topic in the RISAFoundation help file.

RISA Help File

Tags: RISAFoundation, New, Retaining Walls

April 7, 2020 | RISA-3D, Concrete, New, Shear Walls

Understanding Out-of-Plane Shear Capacity of Concrete Wall Panels

When designing concrete shear walls for lateral loading, RISA-3D includes design checks for both in-plane and out-of-plane shear. In the condition where a concrete wall is under both axial tension and out-of-plane shear, the out-of-plane shear limit state for a specific region within the concrete wall detailed report includes the details shown below: This limit state may cause users to ask the question: “why is the a phi*Vns term listed when no out-of-plane shear reinforcement is present?” The answer is that when calculating the out-of-plane shear capacity of the concrete wall, RISA-3D considers Shear Friction developed at the crack interface. ACI 318 code defines shear friction as the shear transfer across any given plane, such as an existing or potential crack, an interface between dissimilar materials, or an interface between two concretes cast at different times. In this case, the existing/potential cracks condition applies. When axial tension and out-of-plane shear are applied to the concrete wall, cracks will form across the wall thickness as explained by the simplified force diagram shown below: The shear sliding at the crack generates tensile forces Fs in rebar. In return, these tensile forces, Fs cause compression forces, Fc at the concrete crack interface. The…

November 24, 2020 | ADAPT-Builder, ADAPT, Slab, New

Moment Capacity of Slabs with Base Reinforcement

In this video, the calculated moment capacity of a slab with base reinforcement, as well as the cover requirements for base reinforcement are reviewed…

October 29, 2020 | RISA-3D, RISAFloor, Concrete, RISAFoundation, New, v15, v19, RISAFloorES, v13

Updated Shear Contribution for Concrete (Vc) per ACI 318-19

The new ACI 318-19 code has been implemented into RISA-3D v19, RISAFloor v15, and RISAFoundation v13. One of the biggest changes between the ACI 318-14 code and the ACI 318-19 code is the shear contribution provided by the concrete, Vc. ACI 318-14 In ACI 318-14, a simplified equation for the calculation of Vc could be used unless there is axial force present in the member. The area of shear and flexural reinforcement in the cross section was not a consideration when determining the shear strength contribution of concrete using the simplified equation. ACI 318-19 Now, in ACI-318-19, the calculation of Vc is dependent on whether the area of shear reinforcement provided, Av, is lesser or greater than the minimum area of shear reinforcement required, Av,min. When Av > Av,min, the axial load and the flexural reinforcement ratio are included in the calculation of Vc. ACI allows us to use the larger of the results from equation (a) and (b) in the table. In RISA-3D detail report, this calculation will be presented in the shear design tab: When Av < Av,min, ACI 318-19 introduces a new variable, the size effect modification factor, λs. Experimental tests have indicated that the shear strength…