In the space frame age
When we travel, have we observed some spaces in airports, industries or nowadays even in halls without any internal column? Have we seen the high ceiling with a cluster of structural steel members in a geometric fashion?
If we thought it’s a new idea, we are wrong. Right from the 1960s much research has gone into, especially by Buckminster Fuller, and others in the earlier era, developing a large span, light weight, low cost solution to create column-free space. Over the decades, this three-dimensional design has been accepted as an efficient alternative to our standard two-dimensional truss, now being found in petrol bunks, civic buildings and schools, reducing the net cost for the builders.
Simply stated, if we may equate a normal truss to alphabet A, the space frame is like a triangle, held rigidly at its three junctions. As we add on triangles made of steel members in all directions, horizontally, vertically and diagonally, a visually complex web gets formed. Actually, it simplifies the load transfer by picking up the load, instead of pushing it down and taking it across to the supports in multiple interlocked directions.
Normal causes of truss failure and avoiding which attributes to cost like tension and deflection become minimal here, being distributed across each small member. No member can fail unless the adjoining one fails, which is held by the next one, and so on. In the process, the design can be achieved with less steel and can cost less, especially for long spans.
Space frames are commonly built with steel though concrete, aluminium and timber have also been tried out. The nodes where the members converge, need a specially molded ball joint, for 8 or even up to 12 strut members need to be fixed at one point. The required design may specify single layered frame, multiple layers, curved profile or horizontal one. More the layers, more complex is the lattice of triangle, squares, hexagons or the geometry used, but they can span across wide spaces with heavy loads. Height of each layer, section of strut members and size of the grid vary as per the type of support, kind of loads and the frame system; hence demand expert design and supervision.
Experts like Anil Laul have experimented with space frames to reduce costs, e.g. replace ball joints by cup joints and such others. It’s good to see space frames today even in small towns like Srikakulam built by architect Bheemesh.
If they are efficient, why are they not found everywhere? Each member dimension has to be accurate; the properties of all materials have to be as specified and the structural behaviour has to be achieved as calculated. With no prior experience in handling space frames, people tend to initially hesitate to use this idea. However, once used, it can prove its potential.