The New Parliamentary Building - Portcullis House

The Forces in Roofs Simon Course, a Graduate Member writing from Salisbury, has explained why calculations for tie forces are often wrongly derived: Consider a simple roof construction, as shown in Fig 1, with all three joints pinned and a rafter UDL. When checking submissions for Building Regulation approval, it seems that many engineers derive the tie force (and hence the load for the rafter/tie connection design) by using the expression T=R/tane. As tane=2H/L, this gives T=RL/2H. This is in fact incorrect.

As my year in office draws to a close, my immediate reaction is to wonder exactly where the last 12 months have gone! It really does seem only a short time ago that I gave my address - ‘Promoting the profession’ and, the next day, embarked on a whirlwind round of visits to Branches, Sections and, more recently, international Divisions of the Institution. Dr John Roberts

This paper presents a practical method for designing bulb-flat-stiffened plating against local buckling, without limitations on section slenderness. The aim is to improve the current shape limitation requirements of BS 5400: Part 3, which are known to be unduly conservative. This is of particular concern when applied to assessment of existing structures. Behavioural insight and validation is provided by 60 finite element (FE) solutions. A strength curve for the design of plate panels, which is a function of the system-critical stress, expressed as the critical slenderness parameter ep, given in a previous paper, is verified by further numerical data in this paper. A modified Perry equation is proposed for the design strength of imperfect bulb flat stiffeners, taking into account the restraint provided by the plate. The strength of the stiffened plate is given byadding the stiffener strength to the plate strength. S.K.G. Chou, J.C. Chapman and P.C. Davidson