Steel structure and concrete elevated basement floor with void space below the floor to allow for movement of expansive soils. Different buildings have different requirements, so not surprisingly there is no 'one steel structure size fits all' most appropriate solution. Clearly the requirements of each steel Structure or steel flooring vary depending on the type of use, but there are also some more subtle issues to consider and these are highlighted below. The reason why composite construction is often so good can be expressed in one simple way - concrete is good in compression and steel is good in tension. By joining the two materials together structurally these strengths can be exploited to result in a highly efficient and lightweight design.