Portal Frames

Portal Frames

Portal Frames Definition -“A continuous rigid frame with a restrained joint between the column and beam.”

Portal frames can be used for many building types such as commerical and industrial, such as in this project a warehouse. Which is a large span open area, which makes steel portal frame a perfect option. Portal frames work where the frame acts as one structural entity where stress is distributed through the frame.

Advantages of portal frames:

• Portal frames are simple in construction, where limited number of trades and skills are required to construct.
• It has a very large spanning comabititly where it can span 15-45m column free.
• It can constructed quickly and easily through its basic shape.

Types of Portal Frames

There are three types of portal frames these are rigid bases and 2 Pin and 3 Pin portals.

Rigid Bases

• There are lower bending momnets in frame which means the frame can be lighter and have a heavier footing.
• The maxium bending moment is at the apex knee and base of the frame.

Pinned Based (2 Pinned & 3 Pinned)

• These are ralely used anymore as the rigid bases are the perfered option.
• It has a simplified footing where the bending moments are transmitted vertically to the ground.
• This option is more suittable for poor foundations then ridged bases.

Choosing Pinned Base or Rigid Base depends manily on the economics of the construction project where rigid base is more economical for smaller spans.

SOUTHERN CROSS STATION

Southern Cross Station

Architect: Nicholas Grimshaw and Partners, in partnership with Jackson Architecture
Client: Leighton Contractors
Developer: Civic Nexus Consortium
Structural Engineer: Winward Structures
Construction began in 2002 and finished in late 2006, at a cost of $700 million

Southern Cross Station is an example of excellence in construction technology. It's redevelopment has converted the former Spencer Street Station into a light, open and modern transport precinct.It is an open and light-filled space, with complete glass frontage to the street. The basis of the design was ease of passenger circulation and practicality.

A complex steel framework of beams and struts creates a wave-shaped roof, which has attracted international attention. The roof contains 3200 tonnes of structural steel and over 7,000 individual aluminium roof panels. Each has its own unique shape and position on the roof.

The roof also performs many environmental functions:
natural and mechanical ventilation systems to exhaust diesel, smoke and other fumes. A highly durable and transparent plastic sheeting between roof sections enables the metal structure of the roof to flex as environmental conditions change. A drainage system enables water runoff from the roof to be collected and directed into the storm water system.

Southern Cross station has a spectacular design especial in relation to the roof and offices. Southern Cross is one of the best examples of great architecture and construction development that Australia has to offer.

Steel Portal Fame Construction Drawings

WALL SECTION

Portal frame construction is therefore typically seen in warehouses, barns and other places where large, open spaces are required at low cost and a pitched roof is acceptable

SECTION A-A

Portal frame construction is a method of building and designing simple structures, primarily using steel or steel-reinforced precast concrete although they can also be constructed using laminated timber such as Glulam. The connections between the columns and the rafters are designed to be moment resistant

BOX GUTTER DETAIL

A box gutter does not hang onto the edge of a roof or on the edge or side of a house as many moderrn pre-formed metal gutters do. A box gutter is actually built into the bottom of the roof or into the roof overhang. The foundation of most box gutters is wood that is then covered with thin sheet metal such as tin, copper, lead, stainless steel, or some other metal that will not readily corrode.
 

Steel Portal Fame Construction Drawings

WALL SECTION




PORTAL FRAME

Generally portal frames are used for single storey buildings but they can be used for low rise buildings with several floors where they can be economic if the floors do not span right across the building. A typical configuration might be where there is office space built against one wall of a warehouse

Bunnings Warehouse - Long Span Structures

With an objective to find a existing long-span commercial building, I decided to look at Bunnings Warehouse located at 10 School Road, Corio. I select Bunning Warehouse as I thought it would demonstrate the main features of a long-span commercial building with the use of steel.

From this photo you are able to observe the use of the steel portal fame and its connection to the central column

From this photo you are able to see how far the long-span spans


From this photo you are able to see the relationship between the long span steel and the roof.