Different span structure

Portal frames, known as "门式刚架" in chinese, are a versatile (多功能的) structural system widely used in industrial, commercial, and agricultural buildings. These frames consist of columns and beam rigidly connected to form a "portal" shape, offering efficient load-bearing capabilities and flexibility in design. Below is a detailed breakdown (详细分类) of their structural forms.

The simplest form, featuring a single bay with two columns and a beam. It is ideal for small to medium-sized building such as garages, workshop, and storage facilities. The roof can be designed as single-ridge single-slope (one slope) or single ridge double-slope (two slopes meeting at a central ridge), depending on drainage requirements. This form is cost-effective and easy to construct, with spans typically ranging from 9m to 36m.

Comprising multiple adjacent single-span frames, this form is suitable for large-scale applications like supermarkets, warehouse and aircraft hangars. The middle columns can be designed with hinged connections to reduce horizontal thrust on foundations, while the roof may adopt a multi-ridge multi-slope configuration for complex layouts. Multi-span frames allow spans up to 72m in modern designs.

Designed to support overhead cranes, this form incorporates crane girders attached to the column. It is commonly used in manufacturing plants and logistic centers. Key considerations include increased column rigidity to withstand dynamic loads and compliance with crane safety standards (e.g AISC or EN 1993-1-1)

Integrates an intermediate floor (mezzanine) for additional workplace or storage. The mezzanine can be supported by secondary beams or standalone columns (独立柱), and its design must account for live load (活荷载) and access requirements. This form is popular in mixed-use facilities.

A portal frame with cantilevered eaves features extended beam (1m-3m) projecting beyond the columns to create shaped or weather-protected areas like walkways, loading zones, or aesthetic overhangs. This design enhances functionality by providing shelter while maintaining structural integrity. (完整性)

• Material Selection: Lightweight steel (e.g H-shaped section) is standard for cost and efficiency, while concrete or composite materials may be for fire resistance.
• Bracing System: Diagonal braces (e.g cross bracing, k-bracing) and diagonal braces ensure lateral stability against wind and earthquake.
• Connection Details: Rigid connections (weld and bolt 焊接和螺栓) transfer bending moments, while hinges (铰链接头) reduce foundation loads
• Enclosure System: Corrugated metal sheets, sandwich panels, or glass curtain walls are common for cladding, with purlin and girt systems supporting the load.