book-2

STRUCTURAL DETAILING 145▲ 7.26 Jussieu University, Paris, France, Edouart Albert, 1965. Beam geometry expressesthe bending moment diagram.Greek columns became the touchstone of this concept . . .’ 8 In otherwords, designers elaborate structural details in order to clarify theexpression of structural action. First, then, unelaborated structuraldetailing.The exposed first floor beams at Jussieu University, Paris, express theirinternal structural actions. Steel box-beams, curved both in elevationand plan, express the relative intensity of their bending moments (Fig.7.26). The beams are simply supported and their elevational profilestake on the parabolic forms of their bending moment diagrams. Onenotes in passing that the architect has privileged the articulation ofbending stress rather than shear stress. Shear stress, which usuallyincreases linearly from a value of zero at a mid-span to reach its maximumvalue at the ends of a span, is rarely expressed. The suspendedfloor trusses at Centre Pompidou, Paris, are an exception (see Fig.7.53). Their diagonal web members increase in diameter as they approachthe truss supports in response to the increasing value of shear force.By varying the beam flange-width in plan at the university, the beamsnarrow at their ends to match the diameter of the tubular-steel columnsinto which they frame. Such a high degree of column slenderness, giventhat the columns support five floors, indicates their inability to resistlateral loads and the necessity for the concrete structural cores elsewherein the building plan to provide overall stability. The level of transparencyprovided by these small diameter columns is especially appreciated