New Zealand's Design and Construction market voiced their need and challenged the precast industry for improved precast products. Hearing the call,
The Precast NZ Association and their members have embraced this challenge and ventured on a journey to deliver product quality assurance across the Industry. But how did they do it ?
Read through for an insight into PCNZ's latest industry initiatives and technology development case studies.
The Precast NZ Plant Certification scheme provides customers with a level of confidence that products purchased from a PCNZ Certified Plant will be from an established operator with appropriate manufacturing facilities, testing systems, quality assurance programs, levels of expertise and experience that has been subject to independent third party audit. The number of precast plants meeting this level continues to increase and those that do are identified on the PCNZ web site: http://www.precastnz.org.nz/plant-list/
Precast NZ furthers the wider construction interests by active involvement in New Zealand standards including concrete design and conditions of contract. We expect to shortly commence a review and update of the combined Master Builders / Specialist Trades conditions of subcontract SA-2009 to recognise the 2015 amendment to the Construction Contracts Act.
Carlaw Park was once a significant destination for Auckland; in 1844 it was Auckland’s first flour mill, then In later years it became a Chinese market garden until 1921 when it was officially opened as the home of Auckland Rugby League. In 2002 the site was vacated and became an under-utilised and overgrown car park. In 2012 Auckland University began the transformation of the site into a dynamic student accommodation village, This project brings a richness of activity back to the site and revitalizes a forgotten Auckland landmark.
Modulated into three ‘blocks’ The Carlaw park village is manufactured using Architectural Precast Concrete. Monarc Creative Precast 'Tabasco' colour concrete was selected for its local resource abundance and natural pigmentation providing an earthen undertone. Colours were accentuated with post erection concrete stains. Dynamic window depth was created through custom Precast mouldngs providing continuity of appearance and a depth
Carlaw Park celebrates sustainability excellence and was awarded the 2015 Concrete 3 Sustainability award for Excellence in Commerical Concrete Construction.
Construction of this 6000 square metre building, “Te Piringa”, designed by Opus Consultants, marks the 50th anniversary of the university.
The steel-structured building is being constructed on a hilly area of Hamilton and because of the deep clay subsoil on the site there was a necessity to reduce the overall deadload on the building . . . and this is where Litecrete comes in.
Litecrete lightweight precast concrete cladding panels, at 150 mm thick, are half the weight of standard precast, so that the architect can still achieve a solid concrete look AND take advantage of reduced deadload, smaller structural steel members and overall cost-savings.
The 5-storey office tower is clad with vertically-ribbed Litecrete panels which, along with vertical sunshade vanes, symbolise the tukutuku reed panels of a traditional meeting house. Litecrete was also used for internal wall areas to continue the emphasis on creating light, spacious, open areas for working and studying in, and for making the building as energy-efficient as possible.
Several buildings are currently under construction at the Ryman Health Care Petone site, one of these is the Village Centre.
The precast building comprises five (5) suspended levels with below ground basement.
The site is located close to a fault line and the structure is relatively heavy consisting of precast walls, ribs and timber infill suspended floors custom 1200 x 600 shell beams, brick veneer and a heavy roof. In addition, the Engineers Mitchel Vranjes were challenged with a very high water table and liquefiable soils which required remediation and also the requirement to increase seismic loads by a further 30% due to an Importance Level of 3 (high occupation level).
Traditional elastic design using these parameters resulted in a relatively high seismic coefficient, well in excess of unity.
From previous building designs for Ryman throughout NZ, Mitchel Vranjes anticipated extreme design difficulty and very high uplift loads.
They also recognized that the traditional use of transfer beams supporting shear walls at basement level, would not be possible unless Architectural configuration was changed significantlIn summary, MV elected to design a Base Isolated structure on large prestressed precast beams.
The proposed base isolated structure for this site was considered ideal as this type of solution is particularly suited to a heavy squat type building of low period.The base isolated building will experience a, “period shift”, resulting in lower seismic lateral loads.
The structure has been modelled in ETABS by Opus and the isolators are sized based on the Maximum Credible Earthquake (MCE) event.
The cantilevered columns supporting the isolators, the floor diaphragm immediately above the isolators and the basement raft foundation are all designed for the MCE event; this event also captures the maximum expected drift of the isolator, estimated as 700mm for this building.
Another issue with this site is the potential for liquefaction and the subsequent differential settlements that may be introduced post-earthquake and a very high water table.
The water table is approximately 2.5 metres above the subgrade level of the basement foundation level, this equates to 25kPa up thrust on the underside of the slab.
The MV design rationale was that a 1 metre reinforced concrete slab will effectively counteract this uplift under the action of its self-weight, whilst a thinner slab may be possible we would then have to rely on the flexural strength of the slab to span between columns. This would result in residual stresses within the slab with a reduction in capacity under a seismic event.
A “zero stress” slab was considered to be the most appropriate, this has been constructed at 1 metre depth (25kPa) - balanced! The other consideration for the slab is that it must be adequate for the cantilever moment from the columns, a 1 metre depth slab works well for this loading case and also for punching shear.
Remediation to a depth of 4 metres below slab was also undertaken by the installation of stone columns; these occupy approximately 14% of the overall plan area and comprise 600mm diameter columns at 1.5 metre centres.
Two types of isolators were adopted for this building Lead Rubber Bearing (LRB) - 1000 diameter Sliders (Stainless Steel and Teflon) The sliders were chosen as the internal support columns can be reduced in size due to a reduced moment demand. This reduction in column size was required for vehicles turning within the carpark area.
The sliders are a Teflon type bearing attached to the column.Immediately above this bearing a large stainless steel plate is attached to the underside of the floor diaphragm prestressed shell beams.
The moment in the bearing is distributed half into the column and half into the upper diaphragm; the diaphragm has to be very rigid, thus the use of a two way beams grid system that take the loads. The beam system comprised precast custom made 1200 x 600 shell beams.
The base moment in the column is distributed into the raft slab.The seismic mass is approximately 160,000 kN.y. This was not an option.
The dedicated construction exhibition for Auckland, New Zealand
Following the success of the construction show from the Australian counterpart, Sydney Build 2016 Expo, the new format and show is brought over to NZ as
Casttec Glue is a break-through technology for the precast industry.
Casttec Adhesive bonds detail strips and other architectural elements used in all types of concrete forms.
Casttec Adhesive bonds wood, foam, metal and most plastics to both concrete and metal mold bases.
By eliminating the need to drill holes in the concrete floor for mechanical fasteners, there is no need to clamp and no waiting for adhesive to cure.
Casttec Adhesive does not require any primer and sets almost instantly. Once set the adhesive is extremely strong and will withstand both the pouring and vibrators used during the mold filling. Once the concrete section has been removed, any adhesive residue can be easily removed from the mold using a scraper.
The Casttec System eliminates the need for more costly fixing systems such as magnets, double sided tape, drill and bolts and welding etc.
Casttec Adhesive is faster, easier, and more cost effective than other adhesive systems in the concrete industry.
For more information please call Bill Milligan at Glue Guru. 021-458-344 or email email@example.com.
Check out our website at www.glueguru.co.nz