Structural glass materials and design considerations for building applications

¶ … Glass Structures

There has been a dramatic increase in the use of structural glass in building, as a result of interest from architects and improvements in glass technology. Glass plays an important role as it keeps out rains, transparent yet durable and provides security barriers. Glass is a brittle material and it fails unknowingly without giving out results or permanent deformation. Glass although it is strong is sensitive to surface imperfections. Failure is realized from a tensile component of stress (Wilson, 2008).

Important element in the design is that of redundancy in event of sudden failure of leaf of glass as a result of effect loading or fracture by impurities inherent in glass safety and use of lamination should be taken into consideration.

DYNAMICS OF GLASS MATERIAL

Dynamic of glass materials exist for instance soda-lime glass. Soda-lime glass is mostly used in the construction of industry it is a green tint as a result of the presence of iron in the mix that enable it to lower the melting temperature and reduce floating glass production costs. The properties of soda-lime glass include:

Density 2500kg/m3

Young's modules 70kn/mm2

Poisons ratio o.23

Toughened 120N/mm2

Annealed glass is subject to stress corrosion which is fond to cracking under long duration loads. Annealed glass is also vulnerable to thermal shock that causes cracking due to internal stresses resulting from temperature differences. The modeling of the annealed glass can be done by re-heating the glass the cooling the outer surface. The cooling prestresses the outside skin enhancing the capacity of extreme fibres to be able to resist tensile stress. Residual which is the extend of stress is determined by the rate of cooling. The toughened glass has a minimum residual surface of 100N/mm2 while heat-strengthened have a minimum residual surface stress of between 41-49N/mm2 (Mahesh, 2010, p.9)

The critical area in the design of the glass structure is connection .Connection links the series of elements .The choice of connection type is based on various factors such as:

Adequate tolerance for construction

Cost

Method of fabrication and aesthetics

Strength requirement

In connection the high strength capacity of glass is made use of in transferring a load and this in turn minimizes the depth and complexity of the connection. Connections comprises of edge bearing connection, Hole bearing connection and Friction Grip connection.

Glass can be used as a structural material with adequate safety provided suitable attention to detail in both design and construction, more so, use of laminated glass where appropriate to enhance redundancy.