Portal Frame Section #2

Portal Frame Section

Portal Frame Construction

This is an exterior photograph of the Waurn Ponds Bunnings Warehouse. Within the structure a portal frame system has been used in order to span long distances (upwards of 40 meters in some circumtances) whilst minimising, and even negating the need for cumbersome column supports midspan.



Inside the warehouse, the structural elements combine to create a palpable skeleton. Here we can observe the joint and associated members where the near-horizontal rafter (or beam) connects to the adjacent stanchion (or column).

Of particular interest in this photograph is the supporting haunching that sits on a diagonal slope on the underside of the rafter. Haunching typically extends about 15 to 20% of the overall span from the stanchion, and acts as an extended brace to augment the rigidity of the knee joint.



In the close-up we can gain a better insight into the juncture that connects the stanchion with the rafter. Universal steel beams - not columns - have been used in both instances due to the fact force from the long-spanning rafter creates a large lateral pressure on the stanchion in addition to the downward compressive forces a typical column would incur. A number of heavy duty bolts add the bulk of rigidity through plates and flanges, as they allow a little more flexibility in their join as opposed to welding practices.