Author: Roberts, John
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Roberts, John
The Structural Engineer, Volume 77, Issue 20, 1999
Hipped rafters Two more contributors have reverted to this much-discussed topic. Stuart Marchant writes from London SW18: I have been following the recent correspondence with interest and studying my own roof I fail to understand how Alasdair Beal(1 June 1999) infers that purlins greatly reduce the triangulation forces. The purlins in the roofs that I have seen are generally perpendicular to the rafters with inclined props. These will induce an axial load in the rafter in much the same way as a ridge board, although of a slightly reduced magnitude, resulting in an outward thrust at the wallplate.
The Queen’s Building at Emmanuel College, Cambridge, was completed in April 1995. It provides the college with a 170-seat auditorium, reading rooms, common rooms, and music practice rooms. The building features a stone perimeter frame, constructed from Ketton stone, an oolitic limestone extracted from the Ketton Quarry in Lincolnshire. M.G.T. Dickson and G.R. Werran
Mr P. L. Campbell (Past President) In 1973, not long after the M & S structure was constructed, I was asked by the editor of New Scientist to write an article about the inherent dangers of demolishing ‘special’ structures (pre- and post-tensioned structures, nuclear and offshore installations, etc.), if full information concerning the original design were not available. I believe that such structures should have a plaque stating that they are ‘special’, and full design information should be retained in a central repository in perpetuity for reference by future generations. On the face of it this building had well-grouted tendons, space around it, a useful basement area, and a configuration that suggests to me that demolition using explosives was an obvious option. Was this considered and, if so, why was it rejected?