Rocla® spun building columns are taking pride of place in the new Melbourne Convention Centre, which hosted its first function in July 2009.
Some of the interior columns in the atrium rise to the full roof height of 23 metres between escalators, adding a sense of awe to a spectacular building which will be integrated with the existing Melbourne Exhibition Centre to create a new landmark on the Yarra River.
Another, more important, contribution of the columns to the project was their speed of installation, which helped Brookfield Multiplex meet its construction schedule by providing free-standing, multistorey columns that could be erected in minutes. Originally, the building was designed with composite columns on the basis that construction could be fast-tracked by erecting the steel columns first, to support the upper floor structures, then the columns encased in concrete later.
However, the engineers found that the steel columns alone provided limited load capacity, making the composite solution ineffective as a “fast track” design philosophy.
While seeking an alternative precast solution, Multiplex was introduced to the Rocla® product, which provides large, round columns with a hollow core and a smooth finish, and with a high structural capacity and fire rating built-in.
The unique Rocla® manufacturing process creates hollow, steel-reinforced concrete columns of great strength and relatively light weight by spinning in a mould at high speed. Fittings, accessories and block-outs can be accurately positioned in the factory to facilitate construction on site. Columns can be bolted directly to the foundation using barrel connectors built into the base of the column. The strength of the connection means that the free-standing columns require no propping while still offering some resistance to impact loads, even at 13.5m tall.
Rocla supplied Brookfield Multiplex with 88 columns, all 810mm diameter and most 13.5 metres in length. The longer, 23-metre columns were supplied in two sections which were bolted together on site using a built-in lug joint.
Rocla's engineers worked with the Multiplex team to calculate transfer loads and design special beam connections. Cast-in lugs were provided at the top of the columns for attachment to the bottom of steel floor beams. In other cases the hollow columns were core-filled to their full height to allow hold-down bolts to be installed in the core.
Tim Cogan, of Brookfield Multiplex, said the Rocla® columns provided an ideal solution wherever tall, round columns were required. “They certainly helped to speed up construction and maintain the fast-track nature of the structure,” Tim said, “and they contribute to safety because there's no formwork or propping and therefore less congestion on site.”