If they are very tall, sometimes two or more semi-arches are used.
Used by architect William Anderson in his lighthouses, as well as more classical architecture, this structure allows load bearing walls to contain weakening cut outs such as large windows due to its transmission of horizontal thrust. If they are very tall, sometimes two or more semi-arches are used. It was employed in Romanesque architecture but disguised by other constructions or a roof. With an open partial arch shape, it stands apart from the central building. FTP this is what structure commonly found on the outside of Gothic Cathedrals, including Westminster Abbey and the National Cathedral in Washington D.C.
Used by architect William Anderson in his lighthouses, as well as more classical architecture, this structure allows load bearing walls to contain weakening cut outs such as large windows due to its transmission of horizontal thrust.
{Flying buttress} (accept {Arc-boutant})