Using today's technological knowledge of material behavior we can explain what happens in every structural member of a building. To illustrate the structural concept in a simple way we place a member (a beam) horizontally and support the member in its two ends. If we apply loads perpendicular to its longitudinal axis (see Drawing A) the member will deform as you can see in Drawing B. If we draw some parallel lines perpendicular to its longitudinal axis and apply the loads again when the member deforms we could see that those lines tend to incline toward the center of the beam. When we study the lines that were parallel in the beginning, we will notice that they are closer to each other in the upper part and farther from each other in the lower part. Along the center of the beam they remain at the same distance from each other. We can conclude from this demonstration that in the upper part of the beam we have compression stress, that in the lower part of the beam we have stress of tension and in the center we have a neutral axis with no stress of compression nor tension. The Concretek System is designed responding to this material behavior. In the upper part we have concrete, a material that supports compression and in the bottom part we have steel bars, a material that is very good supporting tensile stress. In the center part we have expanded polystyrene, a material that doesn't support compression nor tension. For structural purposes it is used to occupy the space. The upper part is united to the lower part by diagonal steel bars which are welded to a steel wire mesh on both sides forming a three dimentional steel frame. The resulting construction is very efective resisting structurals loads.