Portal Frame Roof Structure

The portal frame divided into several forms 1.

Portal frame roof structure. Portal frames are generally low rise structures comprising columns and horizontal or pitched rafters connected by moment resisting connections. Portal frames are a simple and very common type of framed structure. Steel portal frames in particular are a cost effective structural system to support building envelopes such as warehouses and shopping complexes requiring large column free spaces. Portal frame structures are designed to span between supports and rely on fixed joints with moment resisting capacity where vertical supports connect to horizontal beams or trusses.

Resistance to lateral and vertical actions is provided by the rigidity of the connections and the bending stiffness of the members which is increased by a suitable haunch or deepening of the rafter sections. They tend to be lightweight and can be fabricated off site then bolted to a substructure. Portal frame structures can be constructed using a variety of materials and methods. Portal frames can be a simple and rapid form of structure to erect creating a wide clear span weather proof enclosure at low cost with little material.

In general the loads and consequent deformations for these frames are in the plane of the structure and hence these are a plane frame structure. To ensure longitudinal stability which column bracing and roof bracing will arrange. Portal steel frame refers to the use of welded or hot rolled h section steel as the main load bearing framework and cold formed thin wall steel c z section steel or channel steel as purlins and wall girt. It is a light weight building structure that uses corrugated single color sheet as the roof wall panel.

Typical portal steel frame. 25 to 35 m are the most efficient spans portal frame with internal mezzanine floor office accommodation is often provided within a portal frame structure using a partial width mezzanine floor. Types of portal frame pitched roof symmetric portal frame generally fabricated from ukb sections with a substantial eaves haunch section which may be cut from a rolled section or fabricated from plate.