Design of Double Curved Self Spanning Horizontal Laminated Glass

How to Validate and Design Large Format Double Curved Self Spanning Glass

Overview

Authors

Photo of Beres Dowdle

Beres Dowdle

Director

Surface Design Consulting Pty Ltd

b.dowdle@surfacedesign.com.au


Abstract

There is a desire in architecture to design and achieve transparent canopies and glazed rooves that are free from the visual clutter and the structure required to support the transparent elements.

Continual development in manufacturing have resulted in longer and more courageous shapes to be formed in laminated glass and there are many examples of long (up to 9m) elements with deep cross sections used in glazed walls.

However, the design of profiled laminated glass acting as a deep section under long term load has no precedence nor codified design guidance. There are many papers and test studies completed on composite laminated sections but little has developed in terms of design rules for the masses.

To make life more complicate there is significant variance between the design philosophy of international glass design codes for flat glass elements acting as a membrane, let alone how to address deep profiled sections.

The changes in manufacturing have far outstripped developments in design codes, leaving the design and assessment of such glazed structures up to the individual design team and requiring a certain amount of development from first principles. This leaves the design open to interpretation and the vagaries of “expert” opinions.

This paper looks at the design requirements and design of horizontally situated large format laminated glass with a double curved cross section profile to act as a self-supporting roof element.

Our paper also includes limits of manufacturing and the impact that this has on the design of glass under permanent creep loading as well as under transient and short term loads including those related to thermal stress.

The paper offers a design method and validation process to meet current design codes along with our investigations into other important environmental related effects brought on by the design requirements of increased transparency

Introduction

Background and reasoning

The quest for transparency in large glazed canopies often results in Architects and Engineers developing and conjuring up complicated and expensive structures that often result in excessive secondary

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Methodology

Difference in Design (Design Risk Assessment -Vertical versus Horizontal Orientation)

The design of profiled laminated glass acting as a deep section under long term loads has no precedence nor design guidance.

There

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Other Risk Factors and Opportunities

Influence and comment on interlayer

As mentioned above the type of interlayer is secondary to the behaviour for the deep section and the analysis adopted considers the system layered as there

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Environmental influences, what next?

We started the design of the canopy, and this paper, with the aspiration of creating a large span glass canopy free of obstruction with maximum transparency.

While we have developed a

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Appendix – Changes in. Design Action from Vertical to Horizontal System

Design Influence / Design Action

Vertical Element

Horizontal Element

Impact on Design

Ý more onerous

Þ similar

ß less onerous

Geometry and Arrangement

Orientation

Vertical typically simple sill to head

May have moment reversal if intermediate support included

Horizontal span from

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Acknowledgements

We thank the Art Gallery of New South Wales, Sydney for their support and access to the prototype

Rights and Permissions

Roark’s Formulas for Stress and Strain, 6th Edition Author Warren C Young

AutoCad – Computer Aided Drafting software by Autodesk

Strand7 – Finite Element Analysis Software by Strand7

Australian Standard AS1288:2006 – Glass in buildings – Selection and installation

Amadio, C and Bedon, C, Effect of circumferential sealant joints and metal supporting frame on the buckling behaviour of glass panels subjects to in-plane shear loads – Glass Structural Engineering (2016) 1:353-373

Hooper, J.A, - On the bending of architectural laminated glass, International Journal of Mechanical Science 1973, Volume 15, pp 309-323

Marinitsch, S, Schranz, C and Tech,M Folded Plate Structures Made Of Glass laminates: a proposal for the structural assessment 2016_Article_Glass Structural Engineering (2016) 1:451-460

Hemlsey, J.A -Chapter 1 Glass Walls, Sydney Opera House pages 1 to 55 Glass in Engineering Science Volume 2 Glass under Load, published by Society of Glass technology 2016