Learning Centre

Project overview

About this warehouse tutorial

Follow the complete workflow from structural model development and load determination through analysis, serviceability review and member design.

Introduction

This tutorial demonstrates the modelling, loading, analysis and design verification of a steel warehouse structure using FeaKALC 3D.

The objective is not only to demonstrate the software workflow, but also to explain the engineering considerations involved in producing a structural analysis model suitable for design in accordance with Australian Standards.

The example consists of two adjoining steel portal-frame spans with cold-formed steel purlins and side girts supporting lightweight roof and wall cladding. The structural system is subjected to gravity and wind actions, with the resulting reactions, member forces and deflections reviewed before the primary members are checked for design capacity.

What the series covers

Development of the structural model geometry.
Definition of preliminary material and section properties.
Determination and application of gravity actions.
Determination of wind actions to AS/NZS 1170.2.
Creation of load cases and load combinations.
Linear elastic analysis using FeaKALC 3D.
Review of reactions, member forces and deflections.
Assessment of precamber and serviceability requirements.
Simplified independent verification of analysis results.
Design verification of primary steel members to AS 4100.

FeaKALC 3D structural model of a twin-portal-frame steel warehouse — Twin-portal-frame warehouse model developed in FeaKALC 3D.

Guide contents

Warehouse workflow

Move directly to a specific part of the engineering example.

01 · Structural arrangement

Model geometry and framing system

The model represents a large twin-portal-frame warehouse with internal valley support and regularly spaced transverse frames.

The warehouse comprises two adjoining portal-frame spans, each approximately 28 metres wide, producing an overall building width of approximately 56 metres.

The building is approximately 48 metres long, with the primary portal frames spaced at approximately 6 metres. The example has an eaves height of approximately 5 metres and a ridge height of approximately 6.47 metres.

A central line of valley columns supports the adjoining roof slopes. The model also includes longitudinal framing, roof and wall bracing, side girts and roof purlins so that gravity and wind actions can be distributed to the principal portal frames.

Overall width Approximately 56 m

Building length Approximately 48 m

Portal spacing Approximately 6 m

Eaves height Approximately 5 m

Ridge height Approximately 6.47 m

Structural system Twin portal frame

Preliminary member arrangement

Preliminary universal beam sections are assigned to the rafters, with universal column sections used for the perimeter and valley columns. Cold-formed purlins and side girts provide support to the lightweight cladding and contribute to lateral restraint of the primary members.

The initial section assignments are not treated as final. They provide a reasonable starting point for analysis and are revised after the deflection, internal-force and capacity results are reviewed.

Warehouse plan and portal-frame geometry showing two 28 metre spans and 48 metre building length — Principal warehouse dimensions and framing arrangement used in the example model.

02 · Gravity actions

Dead and imposed roof actions

Gravity loading is assembled from the supported roof construction, services and structural self-weight.

The roof dead action is developed from the individual permanent components supported by the portal rafters. These include the roof sheeting, purlins, insulation, services and an allowance for suspended ceiling loads where applicable.

Indicative superimposed dead actions

Roof sheeting: 5 kg/m²
Purlins: Approximately 2.5 kg/m²
Insulation: 2 kg/m²
Services: 30 kg/m²
False ceiling allowance: 10 kg/m²
Total adopted superimposed dead action: Approximately 0.5 kPa

The self-weight of the steel members is calculated directly from the assigned section properties and is included separately by the analysis model.

Roof imposed action

For this educational example, a uniformly distributed roof imposed action of 0.25 kPa is adopted. The applicable action for a real project must be confirmed from the current edition of AS/NZS 1170.1 and the specific access, maintenance and occupancy conditions of the roof.

Gravity action calculation for the warehouse roof including roofing, purlins, insulation, services and ceiling — Development of the representative permanent and imposed roof actions used in the tutorial.

03 · Wind actions

Wind pressure cases and frame loading

External and internal pressures are considered for both principal wind directions and converted into loads on the portal frames.

Wind actions are determined in accordance with the project wind parameters, building dimensions, roof slope and enclosure classification. The tutorial demonstrates how the adopted design wind pressure is combined with the relevant pressure coefficients to develop net pressures on the walls and roof surfaces.

Both cross-wind and along-wind directions are considered. The roof and wall zones are reviewed separately because their external pressure coefficients vary with wind direction, distance from the windward edge and roof geometry.

Step 1

Establish wind parameters

Confirm the regional wind speed, terrain, shielding, topography and design importance requirements.

Step 2

Determine pressure coefficients

Select the relevant external and internal pressure coefficients for the wall and roof surfaces.

Step 3

Calculate net pressures

Combine the external and internal pressures to establish the governing inward and outward actions.

Step 4

Convert to frame loads

Apply the surface pressures as equivalent line actions based on each frame's tributary width.

Representative wind cases

The tutorial develops four representative wind cases covering the principal directions and combinations of external and internal pressure. Each case applies different pressures to the windward wall, leeward wall and roof zones.

Cross-wind loading case applied to the twin-portal-frame warehouse — Representative cross-wind pressure distribution and frame line actions.

Along-wind loading case applied to the twin-portal-frame warehouse — Representative along-wind pressure distribution and longitudinal frame loading.

Tributary loading of the frames

Internal portal frames generally receive the full frame spacing as their tributary width. End frames receive approximately half the adjacent bay width, while the central valley support may attract loading from roof areas on both sides.

FeaKALC load elements can be used to distribute area actions to the supporting members. The load direction, tributary region and supporting frame arrangement must still be reviewed by the engineer to confirm that the generated line actions represent the intended load path.

FEAKalc 3D Load Elements — Load elements to apply loads onto frames.

04 · Analysis results

Interpreting the structural response

The model results are reviewed by load case and combination rather than relying only on the final design utilisation.

After the model has been assembled and the actions applied, a linear elastic analysis is completed. The engineer should review the overall displaced shape before examining individual force diagrams.

Key analysis outputs

Support reactions and global load balance.
Vertical and lateral displaced shapes.
Major-axis bending moments in rafters and columns.
Axial forces generated by portal-frame action.
Shear-force distributions.
Critical load cases and design combinations.
Unexpected force reversals or discontinuities.

Three-dimensional result plots provide a useful overview, but they should be supplemented by member-level diagrams and simplified calculations. Congested numerical output can obscure the actual structural behaviour if the engineer does not isolate individual frames and load cases.

FeaKALC 3D warehouse analysis result showing bending moment and axial force diagrams — Representative three-dimensional frame-force diagrams from the warehouse analysis model.

05 · Serviceability

Deflection, supported elements and precamber

Serviceability is reviewed as an engineering problem rather than as a single pass-or-fail ratio.

The initial warehouse model produced approximately 92 mm of vertical movement under the adopted dead actions. This result required more than a comparison with a span-based limit.

The total dead-load movement was separated into the component caused by steel self-weight and the component caused by superimposed permanent actions such as roofing, insulation, services and ceiling loads.

Initial dead-load movement Approximately 92 mm

Estimated steel self-weight component Approximately 17 mm

Estimated superimposed component Approximately 75 mm

Indicative adopted precamber Approximately 20 mm

Why the load components matter

Some dead-load movement occurs before finishes and services are installed. A portion of this movement can therefore be addressed through fabrication geometry or construction sequencing. Other components remain relevant to the long-term position of ceilings, services, cladding interfaces and drainage falls.

The acceptable response depends on the actual use of the warehouse. A simple storage building may tolerate greater movement than a warehouse containing offices, sensitive services, rigid ceilings or closely controlled façade interfaces.

Possible structural responses

Increase the stiffness of the governing rafters.
Add knee braces where appropriate.
Revise the valley-frame arrangement.
Introduce a controlled fabrication precamber.
Coordinate deflection allowances with services and finishes.
Review ponding, drainage and cladding compatibility.

Initial warehouse portal-frame deflection under dead load — Initial dead-load displaced shape before structural refinement.

Portal-frame rafter precamber diagram showing an indicative 20 millimetre precamber — Indicative precamber used to offset part of the permanent load movement.

06 · Verification

Simplified checks against the analysis model

A simplified hand calculation is used to check the scale and pattern of the software results.

A representative rafter line is compared with a simplified fixed-ended beam subjected to a uniformly distributed action. The comparison is not intended to reproduce every aspect of three-dimensional portal behaviour.

Simplified fixed-beam relationships

End moment: wL² / 12

Midspan moment: wL² / 24

Maximum deflection: wL⁴ / 384EI

Support reaction: wL / 2

For the representative loading and section adopted in the guide, the simplified deflection is approximately 99 mm, compared with approximately 93 mm from the three-dimensional model.

The agreement is sufficiently close to confirm the general order of magnitude. Exact agreement is not expected because the portal rafters are inclined, the frame develops axial force, the supports and joints are not identical to the simplified beam and the full model includes interaction with adjoining members.

What the check confirms

The loading scale is reasonable.
The stiffness used by the model is credible.
The moment distribution follows the expected pattern.
The deflection result is of the correct order of magnitude.

Simplified fixed-ended beam calculation compared with the FeaKALC warehouse model — Simplified beam verification used to check the analysis results.

07 · Member design

Steel capacity and restraint assumptions

Member forces from the global model are checked against the section capacities and the actual restraint conditions.

The portal rafters and columns are checked using the governing design actions from the analysis combinations. The capacity review includes bending, axial compression, shear and the interaction of combined actions where applicable.

The section capacity alone is not sufficient. Effective lengths, lateral restraints, fly braces, purlin spacing and the compression flange condition must reflect the actual structural details.

Rafters

Major-axis bending

Review positive and negative bending regions and identify the compression flange for each governing action case.

Stability

Lateral-torsional buckling

Define the unrestrained length using the actual purlin and fly-brace arrangement rather than the complete member length.

Columns

Combined compression and bending

Review effective lengths about both principal axes and the interaction between axial force and bending moment.

Details

Restraint continuity

Confirm that the assumed restraint can be transferred through the purlins, girts, braces and connected framing.

FeaKALC steel member capacity check for warehouse portal-frame rafters — Representative rafter capacity checks using the governing analysis actions.

Warehouse rafter showing purlins and fly braces providing lateral restraint — Purlins and fly braces used to limit the rafter's lateral-torsional buckling length.

Member utilisations — Using FEAKalc 3D design egnine to pass some 380+ members, click on any member to review design report to AS4100

08 · Video series

Warehouse modelling and design

Follow the complete warehouse workflow across three practical FeaKALC 3D episodes.

Episode 1

Creating the warehouse model

Establish the project geometry and create the primary structural members in FeaKALC 3D.

Set up the project environment.
Create the primary portal frames and columns.
Add longitudinal framing and bracing.
Prepare the model for an initial analysis.

Episode 2

Sections, gravity actions and wind actions

Assign the preliminary sections, apply gravity and wind actions, and review the initial analysis results.

Assign steel and concrete sections.
Apply gravity actions using load elements.
Apply representative wind pressure cases.
Review reactions and force diagrams.

Episode 3

Deflection review and member design

Review structural deflections, assess precamber and complete the primary member design checks.

Review dead-load and combined deflections.
Assess possible framing refinements and precamber.
Complete steel design checks to AS 4100.
Adjust lateral-torsional buckling restraint lengths.
Review column effective lengths.

09 · Engineering guide

Preview and download the complete worksheet

Keep the full marked-up example as a reference while following the video series.

PDF engineering guide

Steel warehouse modelling, analysis and design

The downloadable guide contains the project geometry, indicative gravity calculations, wind pressure cases, analysis plots, serviceability review, simplified verification and representative member-capacity checks.

Project geometry and preliminary member arrangement.
Gravity action calculation.
Cross-wind and along-wind loading cases.
Deflection and precamber discussion.
Simplified analysis verification.
Representative member design results.

Preview PDF Download guide

The PDF preview may not be supported by every browser. Open the guide in a new tab.

Continue learning

Related RKALC resources

Continue with related structural analysis and design workflows.