The major cause of the crack is diagonal stress. This fracture is more likely to be found around the supports. The beam will also tend to break near corners where it is under constant pressure from other beams or walls. Beams are naturally strong in the direction of their grain (such as wood) but they can also be made stronger by cross-graining them (i.e., using two perpendicular directions for the grain). A beam with its grain running parallel to the floor or ground would be considered horizontal and could be called a "flat beam", while one with its grain vertical would be called a "round beam". A flat beam is always stronger than a round one of equal size because there is more surface area for the load to be distributed over. A beam is said to be in compression if a force is applied to it that tries to compress it along its length; this is usually the case for beams supporting loads above building floors. If a force is applied to a beam that tries to stretch it out then it is in tension. Beams in tension are typically those holding up high ceilings, such as ceiling beams. As you can see, beams are important components of buildings and need to be taken into consideration when designing or remodeling ones.