Hi Mo et al,

There is a very good but rather expensive book called "Timber as a Structural Material" compiled and edited by Dr David Yeomans, published in 1999 in Aldershot, England by Ashgate as part of their Variorium series. Chapter 7 of this book features an excellent article by Professor Jaques Heyman of Cambridge University in which he provides a discourse on the structural behaviour of Westminster Hall Roof. There then follows letters and commentary from other accomplished engineers such as Sir Alan Muir Wood, R J Ashby, R J Mainstone, Professor A J S Pippard, all of whom contribute towards the debate and arguement on just how Westminster Hall roof actually behaves and performs. The argument examines the role and contribution provided by the corbels (horizontal stick out blocks in the wall) and the wall top. Later structural test programme work undertaken by Professor Robert Mark at Princeton University throws additional light on these matters and his findings appeared in Timber Framing past issue No 30 (Dec 1993).

A third illuminating and essential document to examine about this roof is The Baines Report prepared for the UK Government by Sir Frank Baines in which goes into great detail about the condition of the roof that he encountered at the turn of the 20th century together with his conclusions and recommendations for the repair and strengthening of the roof following the shearing of a corbell and localised collapse of the roof. I have made a visit to The House of Lords reference library and inspected the large folio of drawings that accompany the Baines report and these drawings illustrate a significant amount of old and new reinforcing metalwork has been added from time to time to keep the roof in place but which now has resulted in a 50% increase in dead weight on the walls and corbells. Originally there was no connection between timber and stone other than deadweight and friction. It is permissable to photograph these colour drawings and anyone interested in seeing an extract from a typical drawing can email me for same.

Oxbow Books in Oxford are offering a discounted rate on the Variorim series right now and so if a number of people send an email to marketing@oxbowbooks.com then maybe we could get a collective discount on the Variorium volume.

I hope that this information might help you in your quest to gain a better knowledge and understanding of the structural behaviour of hammer beam roofs and in particular Westminster Hall.

Regards

Ken Hume