Four columns bear load from vaulting above. There are two semi-circular arch across the ceiling and with gothic, pointed arches on four faces it forms a line between the arch peaks and vaulting that is usually filled with rubble.
Concrete is strong in compression, however is generally weak in tension. Therefore when a load is placed upon it it may bend. To make sure this doesn’t happen, steel reinforcement is put in on the tensile face, normally the bottom edge if a floor or beam.
Tension can also occur outwards, so for example a basement [...]
