TribKALC Column Load Rundown and Design

Project overview

From architectural plan to designed columns

The example brings together graphical tributary-area analysis, multi-storey load rundown, automatic column sizing and an independent three-dimensional comparison of reactions and load distribution.

What this tutorial demonstrates

A representative building floor plan is imported into TribKALC and calibrated using a known dimension. The slab boundary, columns, walls and cores are then traced directly over the plan so that the software can establish tributary regions and calculate the gravity action carried by each vertical element.

The calculated column loads are passed into the RKALC column optimiser. Concrete strength, effective height, section type, minimum width and a target reinforcement ratio are nominated before the columns are sized and redrawn on the plan. Any individual column can then be opened in the RKALC reinforced-concrete column calculator for a detailed design review.

Finally, the TribKALC plan can be exported to FeaKALC 3D. A finite-element model provides an independent comparison of reactions and helps the engineer establish sensible upper and lower bounds for the gravity-load distribution.

Learning outcomes

Prepare a suitable plan for graphical analysis.
Import and calibrate a PDF drawing in TribKALC.
Trace slabs, columns, walls and cores.
Apply floor loading and the number of supported storeys.
Review tributary areas and calculated column loads.
Optimise rectangular or circular reinforced-concrete columns.
Review individual column capacity and reinforcement.
Generate a coordinated column optimisation report.
Export the model to FeaKALC 3D for comparison.

Sample building floor plan used for the TribKALC column load rundown and design tutorial — Sample floor plan and tutorial objectives: graphical load rundown, column optimisation, reporting and FeaKALC 3D comparison.

Guide contents

Column load-rundown workflow

Move directly to a particular stage of the worked example.

01 · Typical workflow

A connected analysis and design process

The workflow separates plan preparation, graphical modelling, load analysis, column sizing and verification into clear stages.

Begin with a clean PDF plan spread across the page width and include at least one reliable overall dimension. Import the plan, calibrate its scale and trace the structural elements. Apply floor loading and the number of storeys, then analyse the model and review the calculated tributary areas.

Once the load distribution is accepted, run the column optimiser, apply the selected sections to the plan and generate a report. Individual columns remain available for detailed review in the RKALC column design tool.

Step 1

Prepare

Create a clear, calibrated plan suitable for tracing.

Step 2

Model

Trace the slab, columns, walls and cores.

Step 3

Analyse

Apply floor actions and calculate tributary regions.

Step 4

Design

Optimise, review and report the column sizes.

Flowchart of the TribKALC load rundown and column sizing workflow — Typical workflow from plan preparation through analysis, optimisation and reporting.

02 · Plan preparation

Prepare, import and calibrate the drawing

A well-prepared plan makes graphical tracing faster and reduces calibration errors.

Prepare the PDF

Spread the structural plan across the available page width and add one clear overall dimension. A large known dimension improves calibration accuracy and reduces the effect of picking points a few pixels away from the true endpoints.

Import into TribKALC

Open the PDF from the TribKALC toolbar, select the prepared file and complete the calibration by tracing the known dimension. The background plan can then be made lighter or darker to maintain contrast with the structural model.

Recommended inputClean PDF plan

CalibrationOne large known dimension

Plan displayFit across page width

Visual controlAdjustable background dimmer

Plan preparation and PDF import steps in TribKALC — Prepare the plan, include a large calibration dimension and import the PDF.

03 · Graphical modelling

Trace slabs, columns, walls and cores

The structural model is built directly over the calibrated architectural or structural plan.

Start with the slab boundary and use orthogonal mode where appropriate to keep edges aligned. Trace the complete floor perimeter and internal recesses before adding columns, wall segments and core regions.

The geometry should reflect the actual load-carrying system rather than every architectural line. Check that all slab regions are closed and that supports are positioned consistently with the drawing before proceeding to the load analysis.

Trace the complete slab outline.
Use Shift for orthogonal tracing where helpful.
Insert each column at its correct location.
Trace structural walls and core boundaries.
Review closures, offsets and support positions.

Slab boundary calibration and tracing in TribKALC — Calibrate the plan and trace the slab boundary over the imported drawing.

Columns walls and cores traced in TribKALC with tributary area analysis — Completed structural trace and analysed tributary regions.

Model the load-resisting elements

Columns, walls and cores are entered as distinct support types. This allows the analysed plan to remain visually coordinated and makes the resulting column tags, loads and tributary regions easier to audit.

Where the building has repeated floors, apply the number of supported storeys and the governing floor loading. Irregular levels, podiums, transfers and changing support layouts should be considered separately rather than forced into a single repeated-storey assumption.

04 · Tributary analysis

Apply floor loading and review the load distribution

TribKALC displays the calculated tributary regions, areas and resulting support loads directly on the plan.

Enter the ultimate floor loading and the number of supported storeys, then run the analysis. The coloured tributary regions provide an immediate visual check of which parts of the slab are assigned to each column, wall or core.

Review the total floor area against the known plan area. Unexpected gaps, overlaps or unusually shaped regions normally indicate that the slab boundary or support geometry requires correction and recalibration.

Key review checks

Plan scale: Matches the known dimension
Total analysed slab area: Consistent with the floor plan
Tributary regions: Rational and continuous
Applied loading: Correct ULS action per square metre
Storey multiplier: Matches the supported levels

TribKALC coloured tributary areas and column load results — Review the tributary regions, support loads and total analysed floor area.

05 · Column optimisation

Size the complete column set

Use common design parameters to generate practical preliminary column dimensions across the floor.

Open the optimiser and nominate the concrete strength, effective height, target reinforcement ratio and required section type. A minimum width can be assigned to control architectural coordination, fire requirements or practical reinforcement layout.

The optimiser determines a required rectangular length or circular diameter for each tagged column. Apply the results to redraw the plan, then review any outliers and refine the inputs where a project-specific column needs different assumptions.

Concrete strengthProject nominated

Effective heightStorey-specific input

Section typeRectangular or circular

Target reinforcementEngineer-selected ratio

Minimum widthCommon or column-specific

OutputRequired length or diameter

TribKALC column optimiser and optimised column plan — Enter common design parameters, run the optimiser and apply the resulting sections.

06 · Detailed review

Open any column in the RKALC design tool

Optimisation is followed by a transparent capacity review of the governing column design.

Clicking a column opens its calculated axial action and optimised geometry in the RKALC reinforced-concrete column calculator. The engineer can review the weak-axis, strong-axis and biaxial interaction checks together with the selected reinforcement arrangement.

Bar diameter and bar quantity can be adjusted while maintaining the intended reinforcement ratio. This allows the optimised section to be converted into a practical reinforcement layout that suits cover, spacing, confinement and construction requirements.

Review weak-axis and strong-axis utilisation.
Check biaxial interaction capacity.
Confirm effective length and slenderness assumptions.
Adjust bar diameter and number of bars.
Review fire, confinement and detailing requirements separately.

RKALC reinforced concrete column design review for an optimised TribKALC column — Detailed column review, including interaction diagrams, utilisation and reinforcement selection.

07 · Calculation output

Generate the column optimisation report

The report records the design assumptions, plan output and optimised dimensions for every tagged column.

The generated report summarises concrete strength, effective height, target reinforcement ratio, design code assumptions and the optimisation strategy. A plan image provides a coordinated visual record of the column tags, loads and selected section dimensions.

The schedule then lists each column's ultimate action, section type, minimum width and required length or diameter. The report is a design aid and should be retained together with the engineer's independent checks, project loading basis and final reinforcement details.

TribKALC column optimisation report showing design parameters and plan output — Report cover page with design parameters, assumptions, plan output and the start of the column schedule.

Continuation of the TribKALC optimised column schedule — Complete column schedule showing the optimised dimensions for all tags.

Use the schedule as a coordinated design record

The schedule makes it easy to compare column demand and dimensions across the floor. Large jumps between adjacent columns should prompt a review of tributary geometry, loading, support locations and whether a rational standardisation strategy should be applied.

Final engineering judgement remains essential. Column sizes may be adjusted to suit architectural planning, vertical alignment, transfer levels, construction tolerances and reinforcement continuity.

08 · Independent comparison

Export the plan to FeaKALC 3D

A finite-element comparison helps the engineer understand how stiffness and slab continuity influence the reactions.

Open the saved TribKALC plan in FeaKALC 3D and apply the total gravity action to the slab, or replicate the relevant number of floor levels. Review the support reactions and compare them with the graphical tributary-area results.

The two methods are not expected to be identical. Tributary analysis provides a transparent and readily auditable load distribution, while finite-element analysis reflects relative stiffness, continuity and mesh idealisation. Together they can establish reasonable upper and lower bounds.

FeaKALC 3D model and comparison of support reactions with TribKALC results — Import the TribKALC plan, apply loading and compare the finite-element reactions.

Where the workflow helps

Typical applications

The same process can support early design, design development and independent checking.

Application

Concept design

Estimate column actions and preliminary sizes before a full building model is available.

Application

Design verification

Compare detailed-model reactions against a transparent graphical load path.

Application

Column schedules

Coordinate tags, loads and preliminary dimensions across a typical floor.

Application

Load-path review

Identify unexpected tributary regions, discontinuities and transfer effects.

09 . Video series

Column load rundown and optimisation

Follow a complete building example showing how to generate column load rundowns from an architectural plan, optimise column sizes, produce calculation reports and verify results using FEAKalc 3D.

Episode 1

Column load rundown using TribKALC

Learn how to import an architectural floor plan, calibrate the drawing, trace slabs, walls, cores and columns, generate tributary areas, optimise the column layout and validate the results using RKALC design tools and FEAKalc 3D.

Import and calibrate a PDF floor plan.
Trace slabs, walls, cores and columns.
Generate tributary areas and column loads.
Optimise column sizes and produce design reports.
Verify reactions using FEAKalc 3D.

10 · Engineering guide

Preview and download the complete tutorial

Keep the marked-up workflow beside TribKALC while preparing and reviewing your own model.

PDF engineering guide