It is a known fact that beams and spheres have the ability to carry relatively high loads. Beams are seen in bridges and other structures even since the days of ancient roman architecture. Spheres have even more impressive abilities. Eggs, for instance, can deal with great compression loads without breaking while their shell is ridiculously thin. Pressure chambers also usually have domes at their ends - being able to resist much higher loads than plane surfaces.
I assume the trick is that there are almost no shear stresses - most of the stress is tensile due to the shapes geometry. Generally, materials can withstand loads more easily this way (bending is more destructing than stretching). Can someone shed some light about this mechanism? How the stresses are arranged in a tension-compression pattern? If find it quite challenging to visualize it.
