This page is devoted to frequently asked questions (FAQ) related to Design in SAFE. |
On this page:
Answer: A few thing to keep in mind during review of punching shear include:
Related Incidents:
|
Related Incidents:
|
Answer: Punching-shear force (Vu) should be smaller than the column reaction, and similar to the value of column reaction minus column weight and load within the shear perimeter. Unbalanced moments (Mu2 and Mu3) should be similar to the column moments at the top of the column times the reduction factor (ACI 318 gamav). Shear and moment values should also be factored according to the governing load combination. These values are difficult to index when using an envelope combination, which is not necessary since SAFE will automatically design for all load combinations, selecting the worst case as the governing scenario.
Related Incidents:
|
Answer: As stated in the SAFE design manual, and prescribed by ACI 318 requirements, SAFE uses 2*sqrt(f'c) for shear links (rebar) and 3*sqrt(f'c) for shear studs.
Related Incidents:
|
Answer: SAFE checks punching shear twice, once for column punching through the drop panel, then once for drop-panel punching through the slab. In this sequence, SAFE traces the punching perimeters required for calculation.
An assumption fundamental to the punching-shear check is that each column has one drop. When multiple columns connect to a single drop, two modeling solutions are available, described as follows:
1- Verification examples of punching-shear calculations per various building codes are available within SAFE through Help > Documentation.
2- MacGregor's "Reinforced Concrete Mechanics and Design-Fourth Edition". The underlined sentences explain why ACI 318 Code does not accept equations which include Ixy.
3- "PTI Manual-Fifth Edition". This page shows punching shear equations for corner columns without Ixy.