Most composite structures are designed as assemblies of beams, columns, plates, and shells. Beams are structural members that carry mainly bending loads and have one dimension (the length) much larger than the other two dimensions (width and height.) From a geometric point of view, beams and columns are one-dimensional elements, while plates and shells are two-dimensional. Columns carry mostly axial-compression loads. If a one-dimensional element carries both axial-compression as well as bending loads, it is called a beam-column. One-dimensional elements carrying tensile loads are called rods or tendons. If they carry mostly torque, they are called shafts, but beams and columns may also carry torque in addition to bending and axial loads.