Ram Elements - Tilt Up Wall [FAQ]

 Product(s):RAM Elements
 Environment: N/A
 Area: Design
 Original Author:Bentley Technical Support Group

Can the module design with one layer of reinforcement?

Yes, the module allows one or two layers of reinforcement in the design, though this setting applies to the whole wall.

Can the program design walls of different thickness?

Yes, the user can use different thickness walls on different levels. The wall surface is assumed to be flush on the outside surface. A different wall thickness cannot be modeled for wall segment strips along the length of the wall.

What design codes does the module use?

Currently the program is limited to ACI 318-05 or ACI 318-14. Please note that ACI 318-08 includes changes to Section 14.8 - Alternate Design of Slender Walls (ACI 318-14 Section 11.8) which are included.

How is Tilt-up wall design different than Concrete Wall design?

In the following section, code references are for ACI 318-05. For similar details using ACI 318-14 see [[Tilt-up Wall Design per ACI 318-14]]

According to 14.2.2, walls shall be designed in accordance with the provisions of 14.2, 14.3, and either 14.4, 14.5, or 14.8. Section 14.4 contains the requirements for walls designed as compression members using the strength design provisions for flexure and axial loads of Chapter 10. Any wall may be designed by this method and no minimum wall thicknesses are prescribed.

Section 14.5 is out of this discussion since it contains the Empirical Design Method which we do not have. Section 14.8 contains the provisions of the Alternate Design Method, which are applicable to simply supported, axially loaded members subjected to out-of-plane uniform lateral loads, with maximum moments and deflections occurring at mid-height. Also, the wall cross-section must be constant over the height of the panel. No minimum wall thicknesses are prescribed for walls designed by this method.

All walls must be designed for the effects of shear forces. Section 14.2.3 requires that the design for shear must be in accordance with 11.10, the special shear provisions for walls. The required shear reinforcement may exceed the minimum wall reinforcement prescribed in 14.3.

In short, our Concrete Wall module uses 14.2, 14.3 and 14.4. The tilt-up module uses 14.2, 14.3 and 14.8. 

The Concrete Wall module includes an option for considering seismic provisions (ACI 318 Chapter 21). Seismic provisions cannot be checked in the Tilt-up Wall module.

We do not design lintels in the concrete or tilt-up modules. What I mean is that segments above an opening are designed as a wall segment and not as a beam segment. We only design lintels in the masonry module and just for in-plane loads.

Why are the deflections in the diagrams different than the deflections listed in the Design Report?

The deflections in the diagrams are elastic, first-order deflections. The deflections in the Design Report are the deflections calculated using ACI 318 Alternate Design Method. These deflections use the cracked moment of inertia and forces from the iterative P-Delta analysis in Sections 14.8.

How do you model reveals?

Reveals can be turned on through the Advanced options. The program assumes that the reveal is on the outside face and reduces the overall section and bar depth. The program always assume the critical section depth is reduced by the reveals.

(the cross section may show the bars shifted in the wrong direction, but it has no consequence on the design).

See Also

[[Tilt-up wall analysis error for inactive DOF]]

[[Tilt-up Wall Design per ACI 318-14]]

RAM Elements Masonry Wall FAQ