ABCDEFGHIJKLMNOPQRSTUVWXYZ
1
Design of Building Columns | Q&A | 14 July 2026
2
3
S.No.QuestionsAnswers
4
1Slender RC Columns. Does the program internally perform nonlinear slenderness analysis, or is it limited to ACI moment magnification procedures?Column Designer uses the code-based magnified-moment (moment-magnification) method for slenderness, such as ACI 318 sway/non-sway magnification factors or the equivalent BS 8110 provisions, applied at the individual column/member level.

It does not run a full nonlinear second-order (material + geometric) analysis of the whole frame. That level of analysis belongs to a general frame-analysis program such as ETABS/SAP2000.
5
2Sway vs Non Sway Frames. Can the software automatically determine whether a frame should be classified as sway or non sway, or is this left entirely to the engineer?The engineer inputs relevant parameters, such as story load and story shear, obtained from the structural analysis software (e.g., ETABS or SAP2000). Column Designer uses these values to evaluate the stability index and verify whether the column satisfies sway or non-sway conditions per the applicable code provisions.
6
3Can we design lateral ties here?Tie size and spacing are entered as inputs (under the confinement/tie parameters) and are used to define the confined-concrete region for the Mander model and for moment-curvature calculations.

The program does not independently size or space ties to satisfy ACI 318 tie-spacing/detailing limits (or seismic hoop-zone requirements) for you. The engineer still needs to verify the tie detailing against the applicable code.
7
4For retrofit section, can we assign 2 different rebar properties? Since older and newer rebars have a lot of different propertiesYes. The retrofit workflow supports rebars, and concrete zones, with different material properties within the same section, so the existing (original) bars and the new/added bars can each keep their own strength properties in one retrofit cross-section.
8
5Many software packages require the user to specify the effective length factor K. How does your software determine K for a partially restrained beam-column connection or a semi-rigid frame? Does it calculate K automatically from frame stiffness, or does it rely on user assumptions?K is computed using the standard alignment-chart (Jackson-Moreland nomograph) method, based on framing/end-condition data you provide (or import from ETABS) describing the relative stiffness of the members framing into each end of the column.

This is more than picking a K value from a table, but the alignment chart itself assumes idealized rigid or pinned joint behavior. For a genuinely partially-restrained or semi-rigid connection, that assumption is only approximate, so engineering judgment (or a supplementary frame analysis) is still needed on top of the calculated value.
9
6Can you enlighten us more on what will be the purpose of exporting column details from ETABS to Eagle Eye column designer if ETABS can already perform design and checking of the columns in the model?A few reasons that makes this product useful:

• Capabilities beyond ETABS's built-in concrete design: composite/retrofit (jacketed) sections, arbitrary drawn or imported cross-sections, confined-concrete (Mander) modeling, moment-curvature/ductility evaluation, and dedicated bridge-pier and shear-wall templates and libraries.

• Design-code coverage: Column Designer supports 14+ codes or for cross-code comparison.

• Focused reporting: 3-D P-M visualization, stress/strain plots, and Word/Excel export tailored to a single column submittal.

• ETABS import and batch processing: Column geometries, materials, reinforcement, and design forces can be imported directly from ETABS, allowing multiple columns to be checked efficiently without repeated manual input.

Therefore, Column Designer complements ETABS by providing advanced section-level verification, batch processing, and more detailed reporting.
10
71) For the capacity surface plot, can concrete strain include the confinement effect, since confinement can increase the D/C ratio significantly?

2) Can bundled bars be modeled in a cross-section where size restrictions require it, instead of using auto-design?		1) A confined-concrete stress-strain model (Mander confined, circular or rectangular) can be assigned to the section instead of the default unconfined model. However, while calculating the P-M-M interaction surface the confinement will have no effect as it considers code stress-strain instead of the confined ones.

Meanwhile, the program considers the defined confinement model while calculating and viewing the Moment Curvature of a defined column section.

2) Individual rebars can be placed anywhere in the section, so a bundle can be approximated manually by placing 2 to 4 bars in contact at one location. There isn't a dedicated "bundled bar" object, and the automatic pattern/auto-design tools are built around single, evenly distributed bars rather than bundling logic, so this is a manual workaround.
11
8Does the program calculate the shear capacity, or design the shear reinforcement and detailing requirements, specifically for Special Moment Frames (SMF) or ductile columns?No. Column Designer calculates elastic stresses of the section; that is a stress analysis, not a code-based shear design.

It does not size/space shear reinforcement (Vc/Vs, stirrups) and does not perform the special seismic detailing checks required for SMF/ductile columns (e.g., ACI 318 Ch. 18 probable-moment shear, hoop spacing within the plastic-hinge zone).

Shear design and seismic detailing for these columns still need to be done separately.
12
13
14
15
16
17
18
19
20
21
22
`
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100