Advanced development used in new building

Press, 18 December 1986, Page 34

Advanced development used in new building

The new Bisley Industries, Ltd, building features two advanced developments of a construction technique in which Christchurch is the New Zealand leader, says consulting engineer, Dr Alan Reay. Dr Reay, of Alan Reay Consultants, who designed the Bisley building, explains that the building incorporates “tilt panels” in the walls and mezzanine floors of the building. Tilt panelling is a concrete construction method whereby reinforced concrete panels are poured horizontally on the ground at the construction site and then titled or lifted into position.

The two features of the Bisley building taking this construction technique a step further are right-an-gled section upper wall panels and flooring panels.

In the case of the former, the panels were manufactured on site by pouring the vertical outside wall face and then standing the faces up on the ground and pouring an abutting horizontal panel. The mezzanine floor was created by lowering floor panels of tilt panel

construction into place. “It originally replaced the block wall method for fire-proof boundary walls, being only about twothirds of the cost. In the last ten years there would hardly have been a boundary wall built in concrete block — they are all done in tilt panel,” he says.

Dr Reay says the use of tilt panels is further ahead in Christchurch than anywhere else in New Zealand, mainly because concrete has traditionally been a more economic material in Christchurch. He says this is largely due to the close proximity of river gravels with correctly sized aggregates for concrete mixing. In both applications, tilt panelling has effectively displaced timber frame construction. Dr Reay says the tilt panels were more competitive in terms of both time and expense.

“It really needs an engineer to get behind the method and to push it.” Dr Reay says his consultancy, a leader in structural analysis and design, has designed about 10,000 tilt panels over the last 15 years.

Economies in the tilt panels arise from a variety of factors additional to the low cost of the raw material: work is done at ground level, highly skilled labour is not required, work can proceed simultaneously with other site work and expensive formwork and scaffolding is not required. In the years since, the title panel method has been extended to panels with windows and doorways, and exterior fins. Twenty years ago, the method — originally developed in the United States prior to the first World War — used hydraulically tilted platforms. Nowadays, however, it is common practice to use cranes to lift the panels into position. Dr Reay says the availability of high-capacity mobile cranes has been a factor in the increasing use of tilt panels. Apart from cost and production time, there are many other benefits of the system over alternatives: versatility in design and appearance, excellent weather and fire resistance, different shapes can be created and the panels are easily relocated.