book-2

144 STRUCTURE AS ARCHITECTURE▲ 7.23 Carpentry Training School, Murau, Austria, E. Giselbrecht,1992. Rear elevation.▲ 7.24Web members connect to a truss bottom-chord.vertical slots. This detail simultaneously allows horizontal load transferand unrestrained vertical movement between the plates and the roofstructure.▲ 7.25 Face-loads only are transferredthrough the plate-rod connection.Structural actionsDetailing that expresses structural actions within members and connectionsalso provides opportunities for architectural enrichment.According to Collins, Soufflot, the eighteenth-century Rationalist architectwho reacted against the ornamental embellishment of structuraldetails, advocated ‘simply limiting aesthetic effects to those which logicallyfollowed from the nature of the structural component, and designingthose components in accordance with rational criteria’. 6 But thependulum has swung since the 1700s. Now, architects such as LouisKahn react against bland concrete and timber members muted by theirrectilinearity in both cross-section and longitudinal elevation, and ‘offthe-shelf’steel sections that satisfy nothing other than the outcome ofengineering calculations. Referring to the pervasive use of steel I-beams,Khan criticized structural engineers who used excessive factors-ofsafetyin conjunction with steel beam standardization. In his view, thisled to overly large member sizes ‘and further limited the field of engineeringexpression stifling the creation of the more graceful forms whichthe stress diagrams indicated.’ 7In the following examples where detailing expresses structural actions,including bending moment diagrams, two distinct types of expressionmay be found. In the first, detailing expresses the variation of structuralactions, and nothing else. In the second type, to use Anderson’s words,‘The functionally adequate form must be adapted so as to give expressionto its function. The sense of bearing provided by the entasis of