Infinite Engineers Projects

Infinite Consulting Engineers’ innovative precast-concrete grandstand design helped Blouberg Local Municipality to fast-track the construction of a large community sports and recreational centre in Senwabarwana, Limpopo. The technology also provided a more cost-effective means of building these structures and an end product of a higher quality, both in terms of durability and aesthetics.

Infinite Consulting Engineers designed the grandstand on behalf of Sizeya Consulting Engineers. Siyeza Consulting Engineers was appointed to design and oversee the construction of the sports and recreational centre on behalf of the municipality. Corestruc undertook the integration of the system, while working alongside the principal contractor, Chisa Multi Projects. The various precast-concrete elements were manufactured by Coreslab. Coreslab is one of Corestruc’s approved manufacturers.

The 3,500-seat grandstand was erected in as little as four months. It would have taken 12 months to build a similar structure using conventional in-situ techniques. Constructing the 20 bottom, middle and top raker beams and the seating using traditional cast-in-place methods would have been a seven-month long process, alone.

Constructing the grandstand in this manner has also provided an almost 40% reduction in construction costs for the municipality. This is by eliminating the need to manufacture bespoke shutters and operating a tower crane for almost 12 months on site, among other preliminary and general costs associated with such a project. This is over-and-above the time savings achieved using this system.

The system successfully addresses all of the risks associated with building these complex structures and the most complicated aspect of these sports and recreational centres. Constructing an in-situ structure with the same aesthetic design as the precast concrete grandstands deployed on these projects can only be undertaken by a handful of established contractors. By sub-contracting the construction of the grandstand to specialists, municipalities are also able to ensure large participation in their sports and recreational centres by small construction companies. This also provides immense scope for employment, as well as training and development opportunities for community members.

Infinite Consulting Engineers has been refining and perfecting this grandstand design since 2012. The focus has been on designing an “off-the-shelf system” that reduces erection time and only requires minor design modifications – if necessary. This has been achieved by standardising and reducing the number of precast-concrete elements, while the use of curved columns and flat surfaces for the rakers, benches and side panels has also facilitated quick and efficient installation. Infinite Consulting Engineers has also refined the method of connecting the various precast-concrete elements over the years. The columns are connected to the in-situ bases by components that have been cast into the precast concrete elements and secured using hold-down bolts in the base. The raker beams, seating benches and side panels are secured with dowels that fit seamlessly into sleeves that have been cast into the various precast-concrete elements and into which the grout is then poured. The dowels have also been strategically positioned to facilitate ease of installation. Infinite Consulting Engineers uses Building Information Management (BIM) systems to model the structures to further ensure precision. BIM makes it possible to create models of each precast-concrete element and provide updated design statuses. It also facilitates quality control by enabling seamless tracking and tracing of each precast-concrete element from the design phase through to their integration on site. Infinite Consulting Engineers also uses a suite of commercial software for structural analysis and design.

A lot of innovation also resides within the factories where these systems are manufactured. Far removed from the many variables of a typical construction site, they provide a controlled environment in which to manufacture the precast-concrete elements. Coreslab commenced manufacturing the various precast-concrete elements for the grandstand in mid-October 2021. The manufacture of the 20 tapered columns, as well as 20 front-end and 20 top raker beams were completed in mid-January 2022. This is in addition to the more than 340 seating and 19 back benches; 34 side panels and 76 steps; as well as the structural steel bracing for the structure. The company’s factory features a computerised batching plant and optimised curing processes. Enhanced mix designs are also deployed to produce the concrete that is used to manufacture the various precast-concrete elements, all of which have a 50MPa compressive strength. A self-compacting concrete eliminates the need for concrete pokers and provides an excellent finish. Significant planning also goes into ensuring practicality and turnaround efficiency of the specialised forms used to produce the various precast-concrete elements. To ensure precision, they have been manufactured from steel that has been cut using laser-cutting machines. They enable fast production and are user-friendly to help facilitate the accurate placement of the various cast-in components.

The principal contractor commenced constructing the foundations for the structure in mid-October 2021. They were completed before the builders’ shutdown period that year to enable Corestruc to start erecting the structure in January 2022. This preliminary work included excavation; placement of the stabilised fill; and construction of the in-situ 10MPa concrete bases. Constructed in sound founding material, the concrete bases for the front raker beams and front columns are 500mm thick. For the back columns, the concrete bases are 600mm deep. Corestruc then commenced with the installation of the middle precast-concrete elements. The top of the columns was set out with coordinates to confirm the plumb and position. This was followed by the lining up of the front raker beams with the top and bottom bolts of the columns and then fastening them in place. Corestruc then installed the rear columns, again setting out the top of the precast-concrete elements with coordinates to confirm the plumb and position. The columns were then braced with structural steel. This provided the critical stability that was required at this stage of the erection process, considering the slenderness of the columns. The top raker beams were then installed in the same way that the front elements were placed. Afterwards, they were braced horizontally in a similar sequence to that used for the back columns. This was followed by the placement of the many seating benches. They were lined up with the raker beams and then grouted into position and, in doing so, forming a single monolithic structure. The process was followed by the installation of the side panels and steps. This structure features a roof comprising galvanised structural steel elements, fixed to the concrete structure at strategic positions. Notably, Corestruc’s team achieves tolerances of 3mm when connecting the precast-concrete elements to the foundations and 5mm when integrating the other components of the system.

Members of the South African Institution of Civil Engineering’s (SAICE) Limpopo branch visited the project. Cuthbert Ngairongwe, who heads SAICE’s Limpopo branch, described the innovation as the future of structural engineering and a means of fast-tracking infrastructure delivery in the country. “Your precast technology has taken delegates out of their comfort zones. They have seen for themselves the innovation that has been deployed across the precast concrete value chain to fast-track the construction of projects, while also providing a high-quality final build,” Ngairongwe said.