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Guide / Structural glass supports

Structural Glass Support Conditions: One, Two and Four Edges

A structural glass calculation depends on how the pane is supported. This guide compares four-edge, two-edge and bottom-clamped models and explains what each model represents before it is selected in a calculation.

Structural glass supports Four-edge support Two-edge support

Structural support models Supported and free pane edges 4 · 2 · 1
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Overview

Primary topic
Structural glass supports
Engineering basis
Four-edge support
Review status
Project-specific verification required

Why the Support Model Matters

The support model defines which pane edges transfer reaction and which edges remain free. It affects the structural response, governing span, deflected shape and the calculation route available for the pane. The selected model should represent the real framing or fixing arrangement rather than the most favourable result.

Four-Edge Support

All four perimeter edges are treated as continuously supported. The figure represents edge support around the pane, not a fully fixed connection. Frame movement, glass bite, gasket behaviour and local restraint remain separate project considerations.

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Support Models

Two-Edge Support

Two opposite vertical edges are treated as continuously supported while the top and bottom edges remain free. The engineer should confirm that the actual framing provides the assumed continuous reaction and that the free edges are not unintentionally restrained.

Bottom-Clamped Support

The bottom edge is treated as the supporting edge and the pane responds as a cantilever-type model. A complete balustrade or screen design still requires verification of the base shoe or clamps, fixing forces, support stiffness, glass engagement and post-breakage requirements.

Load Direction

The purple arrows represent an action acting normal to the reference pane. They show load direction only and do not represent a calculated pressure magnitude, stress distribution or deflected shape.

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Applicability

Model Boundaries

The interactive figure is an engineering explanation, not a calculation result. Pane dimensions are illustrative. Project calculations must use the actual geometry, build-up, loads, support continuity and applicable method coverage.

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Interactive Support Model

Interactive engineering figure

Structural Glass Support Conditions

Rotate, zoom and compare the same reference pane with four-edge, two-edge and bottom-clamped support.

Orthographic isometric view

Four-Edge Support

All perimeter edges supported by continuous framing

q normal to pane
Interactive isometric comparison of four-edge, two-edge and bottom-clamped structural glass support conditions
Reference pane: 1200 × 2000 mm

Open this tab to load the interactive support model.

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Frequently Asked Questions

Does four-edge support mean fully fixed glass edges?

No. The figure shows continuous support along all four edges. It does not claim full rotational fixity or rigid supporting frames.

What is free in the two-edge model?

The top and bottom pane edges are free while the two opposite vertical edges provide the continuous support.

Does the bottom-clamped model verify the base shoe or clamps?

No. The pane support model does not verify the fixing system, support stiffness, glass engagement or post-breakage behaviour.

Are the purple arrows calculated loads?

No. They show the direction of an action normal to the pane and do not represent a calculated load magnitude.

Can every calculation method use every support condition?

No. Method coverage depends on the selected standard, geometry and calculation route. VitraLab reports the available route and any applicable coverage warning.

Engineering content is prepared and maintained by VitraLab Engineering. Worked examples record the current calculator workflow and do not replace project-specific verification.