Parametric Study for the Economical Depth of Long Span Arch Type Truss

R B Kulkarni, Professor, Tejaswini A Mugali, Mtech Student, Dept. of Civil Engg. K.L.S Gogte Institute of Technology Belgaum.

Introduction

Space trusses are those systems, which have pin jointed members. Space frames are those which have rigid jointed members. However, as per the definition of Makowshi and IASS (International Association for Shell and Spatial Structures) the word space frame is used as a generic term of which space trusses are merely a subset. The term "Spatial structure" is also used instead of "Space structure." The two terms are considered to be synonymous.

A space frame or space structure is a truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern. Space frames can be used to span large areas with few interior supports. Like the truss, a space frame is strong because of the inherent rigidity of the triangle, flexing loads (bending moments) are transmitted as tension and compression loads along the length of each strut.

The simplest form of space frame is a horizontal slab of interlocking square pyramids built from aluminum or tubular steel struts. In many ways this looks like the horizontal jib of a tower crane repeated many times to make it wider. A stronger form is composed of interlocking tetrahedral pyramids in which all the struts have unit length. More technically this is referred to as an isotropic vector matrix or in a single unit width an octet truss. More complex variations change the lengths of the struts to curve the overall structure or may incorporate other geometrical shapes.