Masao Saitoh

The role of string in hybrid string structure

Abstract In general, tension structure can be classified into two groups depending on the kinds of tension elements used: (1) membrane structures and (2) string structures. Such tension members as cable, rod and chain belong to the string. Cable especially is a most important and representative member. Furthermore, the string structures are divided into two types: thoroughbred tension structures and hybrid tension structures. A thoroughbred structure is a tension structure such as cable-net which is made of strings only. As for tension member, hybrid tension structures can be divided into the following two categories: (1) structures using members, such as semi-rigid hanging members, which are made by changing the properties of tension members for the pure tension structure; (2) structures made by combining tension members with such rigid members as flat arches, beams and struts. Beam string structures (BSS) are typical of this type. Here, hybrid string structures (HSS) are defined as having the characteristics of the latter. HSS are conceptually opposed to thoroughbred tension structures. HSS are aimed not only at the structural rationality including system, detail and construction but also the sophistication of structural expression. This paper reports mainly on the following items concerning string structure, especially the HSS: (1) the role of string; (2) tensile force in string; (3) stress and displacement control by prestressing in string of HSS; (4) classification of HSS by tensile force occurring in string; (5) a method for introduction of initial tensile force to string; and (6) some actual examples of HSS which the authors have designed.

Wind Tunnel Tests on Horn-Shaped Membrane Roof Under the Turbulent Boundary Layer

In this paper, the authors describe about a wind tunnel test for a membrane roof on a civil engineering. Especially, the authors focused on the horn-shaped membrane roof (shown in fig.1). Wind loading is the most dominant load for light-weight structures such as membrane roofs. A wind-force coefficient of typical building type such as box-type is defined in the guideline and the cord, but a wind-force coefficient of complicated shapes such as the hornshaped membrane roof has not been sufficiently reported yet.