Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Arch fill in


It is interesting to note that a situation similar to the arch roof tie found in St Pancras Station and described in John Rastall's letter arose in the design of the Sydney Opera House.

The dead weight of the Opera House roof had to be much greater than that of the St Pancras roof. However, the problem of providing tie resistance against the thrust of the roof over areas of concrete floor pierced with openings was identical.

Design calculations showed that steel ties were impractical.

Instead, prestressed ties, cast free to slide over the auditorium floor and stressed before the arch pedestal units, were used.

This principle partly resolved the problem but where openings would have fouled straight concrete ties, the geometry was generated as trusses and frames in prestressed concrete avoiding these obstructions.

Perhaps John Rastall's fears could be allayed by passing this information on to the engineers and architects for the present refurbishment of St Pancras.

Michael Johns (M), 16 Winton Crescent, Croxley Green, Richmansworth, Herts, WD3 3QX

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.