What is portal structure made up of?

Portal structure, commonly found in architecture and engineering, typically consists of vertical columns (or piers) that support horizontal beams or lintels. These elements work together to create an opening or entrance, often seen in doorways, gateways, or bridges. The materials used can vary widely, including wood, steel, concrete, or stone, depending on the design and load requirements. Additionally, decorative elements may be incorporated to enhance the aesthetic appeal.