Promoting the Profession

The M-beam was introduced in the late 1960s as a replacement for prestressed I-beams in beam and slab construction. Originally conceived for voided slab construction, the M-beam was soon used in contiguous beam and slab and finally in spaced beam and slab construction. The current need for inspection of bridge structures and maintenance of bearings, along with design changes since 1970, has resulted in the M-beam not being a perfect solution for the design configurations in which it is currently used. H.P.J. Taylor, L.A. Clark and C.C. Banks

The International Association for Bridge & Structural Engineering (IABSE) is launching a new quarterly journal entitled Structural Engineering International which replaces its Periodical publication. In many respects, it is representative of the results of a long, hard review of the organisation, its aims, and its byelaws. This is an appropriate moment to draw the attention of all structural engineers to the objectives and achievements of the Association. D.W. Quinion

Expansion joints on bridges have provided severe maintenance problems for bridge authorities throughout the world. Bridge engineers are increasingly endeavouring to design bridges as continuous structures, and not as simply supported structures, in order to minimise these maintenance problems. This paper explains the concept of integral bridges in which the deck is made continuous and also connected to the abutments, so that all expansion joints are eliminated. A design method is explained for a deck of composite construction using prestressed concrete bridge beams, and a demonstration design is presented. This design uses Y-beams, which are being introduced by the Prestressed Concrete Association to replace M-beams. The design method is straightforward and avoids the complication of calculating the effects of creep. E.C. Hambly and B.A. Nicholson