The rotational behaviour of clipped end plate connections was studied by subjecting nine clipped and three conventional or ''unclipped" specimens with varying connection geometry to combined shear and moment and obtaining the corresponding moment-rotation characteristics. It was found that thc clipped end plate connections in this investigation had more than adequate rotation capacity to permit an interior beam connected to a supporting member by this type of connection to achieve its full plastic moment, provided the length-to-depth ratio of the beam does not exceed 20. For the range of rotations that would be cxperienced by clipped end plate connections in a practical structure, a model originally developed to predict the moment-rotation behaviour of conventional shear end plate connections was modified so as to be applicable to clipped end plate connections. Good agreement was obtained between the test values and those predicted by the modified model. No adverse effect on the rotational behaviour of the connections was observed to result from the asymmetry caused by clipping the end plate.Le comportement des assemblages de plaque d'appui agrafCs soumis ii la rotation a CtC analysC en soumettant neuf Cchantillons agrafks ettrois tchantillons traditionnelsde gComCtrie diverse au cisaillement et au moment flCchissant afin d'obtenir les carac-tCristiques moment-rotation correspondants. On a constat6 que les assemblages de plaque d'appui agrafCs avaient une capacitC de rotation plus que suffisante pour permettre a une poutre intkrieure reliCe ii un ClCment porteur par ce type d'assemblage d'atteindre son moment plastique complet, pourvu que le rapport entre la longueur et la profondeur de la poutre ne soit pas supCrieur 5 20. Pour la gamme de rotations auxquelles seraient exposCs des assemblages de plaque d'appui agrafks dans une structure, un modkle d'abord mis au point pour prtdire le comportement moment-rotation d'assemblages de plaque d'appui traditionnels a Ct C modifit en fonction des assemblages de plaque d'appui agrafCs. On a obtenu une bonne similitude entre les valeurs d'essai et celles prCdites par le modtle modifit. L'asymCtrie qui rCsulte de l'application de cette solution n'a aucun effet nCgatif sur le comportement des assemblages soumis la rotation.

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The "PolydOme" is a 25 rn-span timber shell exhibition hall built to commemorate the seven hundredth anniversary of the Swiss Confederation (Fig. 1).The project was an opportunity to present concrete evidence of research. as well as to demonstrate the possibilities of engineered timber structures using simple material means.The project provided an interesting geometrical challenge, necessitated partly by the fact that timber structures inherently require geometrical precision and partly by the form of the roof.The floor area of the building measures 25 m X 25 m and the maximum height of the building measures slightlv less than 7 m. The walls, which are glazed with the exception of small service rooms located at the middle of the wall, have a maximum height of 3 m.The roof is geometrically a spherical cap with a radius of nearly 2$ m and an effective static height of approximately 10 cm which puts the roof into the Thin Shell class for structural behaviour. relying principally on membrane action to transmit loads to the supports. The roof has eaves which extend out beyond the walls a maximum of almost I m. The roof system has circular ribs which follow meridian arcs of the sphere in two orthogonal directions. that is to say that the ribs all have the same spherical centre. The points of intersection of orthogonal ribs at the exterior border form a planar arc which also respects the spherical geometry (Fig. 2). Roof ConstructionThe roof behaves structurally like a stiffened shell supported principally by four concrete abutments at the corners of the building. The abutments are tied together by foundation walls since the abutments resist horizontal as well as vertical forces. Posts having a section of 80mm X 12() mm are located in the glazed walls of the building to provide minor supplementary vertical support for the shell between the abutments.The ribs and decking of the shell were all built from one standard small-size section of Swiss spruce boards (27 mm X 120 mm) finger-jointed to a maximum length of 19 m.Each rib consists of two boards separated by the thickness of a board in order to allow one board of an orthogonal rib to pass between them at a point of intersection. As a result, the out-ofplane eccentricity between two orthogonal ribs is acceptably small and the detail at the intersection point of two orthogonal ribs is simple and efficient. with two boards running continuously in each direction and, therefore. no perpendicular-to-grain stress problems. Short filler pieces. the lengths of which vary for different pairs of intersection points, were placed between the separated boards to offset the out-of-plane eccentricity and to prevent local buckling of the in-82 Structures Worldwide Structural Engineering International 2/93

the first part of his work was received. The second part is not only as interesting, but as trustworthy and deserving of high commendation as the first. There can be no doubt whatever that the work will take a first place in literature. Michael.