A portal frame is a lightweight, rigid structural system commonly used in industrial and commercial buildings. It consists of two vertical columns connected by a horizontal beam or rafter, forming a sturdy "portal" shape. Typically made of steel or concrete, portal frames provide large, column-free interior spaces, ideal for warehouses, factories, and aircraft hangars. Their design efficiently resists vertical and lateral loads through moment-resisting joints, minimizing material use while maximizing strength. Advantages include cost-effectiveness, quick construction, and adaptability to various spans and cladding options. Variations include single-span, multi-span, or tapered designs to meet specific load and architectural requirements.