Concrete column section properties are calculated from the cross-section dimensions of the member. The calculated moments of inertia values are multiplied by the user specified cracked section factors to determine the final inertias used in the program.
Concrete wall section properties will be calculated from the user assigned wall thicknesses. The walls thickness for in-plane and out-of plane stiffness (but not axial) will be modified by the cracked section factor assigned to the member.
Beam section properties are also calculated from the cross section dimensions of the section. Some or all of a beam's cross sectional dimensions are provided by the user. However, the user can select an option to have the program calculate the flange dimensions for T beam (see RAM Modeler manual). Where this option is selected the dimensions are calculated as follows:
If the beam is under a two-way slab the effective flange width will not consider the distance to the adjacent beam but revert to a flange width of span length / 6, otherwise the rules below will apply.
ACI
| Setting | Description |
|---|
| ACI 8.10.2 Beams with slab on both sides |
- Flange width < Span Length / 4
- (a) Flange Overhang < 8× Slab Thickness
- (b) Flange Overhang < Clear distance to next web / 2.
RAM Concrete Analysis currently considers half the distance between beam centerlines when limiting flange overhang per 8.10.2 (b).
|
| ACI 8.10.3 Beams with slab on one side |
- (a) Flange overhang < Span Length / 12
- (b) Flange Overhang < 6 x Slab Thickness
- (c) Flange Overhang < Clear distance to next web / 2.
RAM Concrete Analysis currently considers half the distance between beam's centerlines when limiting flange overhang per 8.10.3 (c).
|
BS8110
| Setting | Description |
|---|
| BS8110 3.4.1.5 Effective Width of T Beam |
|
| BS8110 3.4.1.5 Effective Width of L Beam |
- Flange Overhang = lz / 10
Where lz is the clear length of the beam.
For user specified T Beam Sections, RAM Concrete does not check if the dimensions are within the code specified limits of 8.10.1, 8.10.3 or 8.10.4 or BS8110 3.4.1.5.
|
AS3600
| Setting | Description |
|---|
| According to AS 3600 Clause 8.8.2 |
Effective Width of T-Beam, bef = bw + 0.2a
Effective Width of L-Beam, bef = bw + 0.1a where |
a
| = | the distance between points of zero moment, which in continuous beams is taken as 0.7 times the beam length | |
bw
| = | the web width |
|
EN1992
| Setting | Description |
|---|
| According to EN 1992 Clause 5.3.2.1 |
The beam's calculated moment of inertia about its major and minor axes, and axial stiffness, are both multiplied by the user specified cracked section factor to determine the properties used in the analysis. |
CSA A23
| Setting | Description |
|---|
| According to CSA A23 clauses 10.3.3 and 10.3.4 |
The effective width is as follows:
- T-Beam: lesser of 1/10 of the span length, and 12 times the flange thickness
- L-Beam: lesser of 1/12 of the span length, and 6 times the flange thickness
|
Note: Where a T beam is located within a two-way slab the program does not ignore the beam flange contribution when calculating the properties of the beam to include in the stiffness contribution to the meshed floor. In this respect the program is double-counting the slab area of the beam flange in two-way slabs. The major impact of this double area is the unrealistic increase in the axial stiffness of the floor. As the floors are primarily subject to bending and shear forces this stiffening may not be significant however if necessary the engineer can provide a rectangular beam reflective of the beam web when modeling beams in two-way slabs.
