	Product(s):	RAM Concept
	Version(s):	Any
	Environment:	N/A
	Area:	General
	Original Author:	Bentley Technical Support Group

What RAM Concept Can Design

RAM Concept is intended for the analysis and design of elevated (suspended) concrete floors and mat foundations (rafts). These floors or mats can be conventionally reinforced concrete (RC), post-tensioned concrete (PT), or a hybrid. A hybrid floor is one that contains both RC and PT areas. For example, most PT floors have some areas, such as pour strips or elevator core slabs that are designed with mild reinforcement.

RAM Concept can also design the following:

Pile-supported mat foundations
Combined wall foundations
Waffle slabs
Pour strips
Single frames and beams using the Strip Wizard. Refer to the RAM Concept Manual chapters "Using Strip Wizard" and "Strip Wizard Tutorial."

What RAM Concept Can Design with Limitations

The following have been analyzed and designed using RAM Concept. Specific limitations and other notes are

Retaining Walls. While RAM Concept is not optimized for this use, it can perform most of the analysis and design tasks if you are very careful. Care must be used as RAM Concept assumes that gravity loads are in the downward Z direction. You need to set all of the self-dead loading load factors to zero and create your own self-weight loadings. You probably want to apply these loads at the mid-slab depth; otherwise the eccentricity will add a self-weight moment to the slab. While RAM Concept's design cross section reports all of the moments and forces on the design cross section, RAM Concept does not perform design considering all of the forces and moments. Specifically, RAM Concept does not consider the Mz value in design, because RAM Concept does not specify the positioning of reinforcement that is important for Mz design. RAM Concept does not consider “P-Delta” effects.
Slabs on Ground. The expression “slab-on-ground” is often used to described residential house slabs. These slabs can be analyzed and designed as spring supported mat slabs. However, the designer should use engineering judgment to determine if mat analysis and design techniques are suitable for such structures. Design guidelines and the lift parameters outlined in the PTI publication "Design and Construction of Post-Tensioned Slabs-on-Ground" and not included in ACI 318 are not implemented in the program.

What RAM Concept Cannot Design

RAM Concept cannot design the following:

Sloping or tapering slabs. Stepping slabs can be modeled. However, each slab and beam is a level member of a single thickness.
Pan joist systems. Pan joists can be modeled and analyzed as T-beams. However, there is not a way to model tapered stems and code specific provisions for repeated joists (e.g. reduced shear requirements ACI 318-11 8.13.8) are not considered.
Deep beams. The analysis assumes that "plane sections remain plane," which typically does not apply to deep beams. Code specific provisions for deep beams, such as ACI 318-11 10.7 and 11.7) are not considered.
Beams of seismic moment frames. The seismic provisions in ACI 318 Chapter 21 are not implemented in the program.
Voided slab systems, like bubble deck.

Is there a limit on the size of structure modeled?

The only limit is the performance of the computer hardware. The analysis run time is approximately proportional to the square of the number of nodes in the model, so large structures may take a significant amount of time to analyze. Design time is approximately proportional to the number of span segment strip cross sections. The RAM Concept manual contains a section “Decreasing calculation time” that contains more detailed information on this topic.

Is there any restriction to the maximum thickness of slab that can be modeled?

RAM Concept's analysis of slab elements considers shear deformation as well as bending deformation. This ensures that RAM Concept gives reasonable results for both thin slabs and thick slabs. In general, RAM Concept's design provisions apply the code requirements that are appropriate for slabs with typical span-to-depth ratios. If the geometry of your slab is outside the usual ranges (e.g. a thick grade beam), you may need to consider if any special design considerations are necessary.

Can RAM Concept design more than one story at a time?

Not by itself. You can use the RAM Structural System to integrate numerous floors into one large model.