RMD KWIKFORM – DIG A LITTLE DEEPER…

Basement construction remains an important element of mid to high-rise construction, with an increasing trend for basements to go deeper. Research by RMD Kwikform has shown that contractors in Europe are facing a shift towards deeper basements – more than any other region in the world. With this in mind, which support systems offer the best solution for Irish contractors undertaking basement excavations for mid to high-rise builds?

Extensive basements in mid to high-rise construction are very common, with most favouring specialist groundworks contractors for these projects. Not many contractors will have their own ground support systems, so it will come as no surprise that those working on high-rise projects will turn to a specialist contractor to assist with this work. Research that surveyed a range of leading general and specialist contractors, plus engineering consultants, found that contractors around the world will typically hire shoring systems or use structural steel methods, rather than use their own ground shoring equipment.

But when it comes to selecting ground support, what solutions are available and what kind of considerations will affect a contractor’s decision over which one to opt for?
There are two main options available: ground shoring systems or structural steel shoring systems. The depth, as well as the length of time that the system is required for and cost, all come into play when deciding which solution is the most appropriate. Structural steel for basement shoring is still popular around the world, particularly in regions such as South America and Asia Pacific. However, for contractors in Ireland, dedicated ground shoring systems would often be a more appropriate solution for basement excavations in mid to high-rise builds. There are a number of reasons for this.

One of these is the length of time that a ground support system is needed. In short, after a duration of 26 weeks, structural steel is generally a more cost-effective option. Any less than 26 weeks, and ground shoring systems will be a better choice for contractors. With most basement excavations for mid to high-rise builds unlikely to take more than 26 weeks, a ground shoring system should be the preferred choice.

Structural steel is slower to install, due to the need to fabricate sections on site and weld them into place. The availability of skilled labour for structural steel is also a consideration, along with the health and safety issues that come from having hot trades on site.
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Furthermore, the certainty of a construction programme can also influence which ground support system is used. If contractors are fairly confident that the project can be delivered within a timescale of less than 26 weeks, then hiring a ground shoring system will be more cost-effective. But for longer projects and ones where the construction programme is subject to change, structural steel can provide greater flexibility. This is a consideration that contractors need to bear in mind. The next factor is that, as basement depths increase, so does the importance of using load monitoring equipment. With the trend for basement excavations in Europe to go increasingly deeper identified, this is a consideration that should not be overlooked. Ground shoring systems can manage wall deviations to a much greater degree and provide more accurate and effective load monitoring capabilities.

SMART FEATURES

The latest ground shoring systems feature a range of intelligent features too, to help contractors ensure equipment can be erected quickly and easily, improving productivity while delivering assured ground support. This includes integrated mechanical isolation on prop hydraulic units, which provides safety and design benefits, and fully modular and interchangeable waler systems with full moment joint capacity. This offers complete flexibility when selecting waler extensions and prop positioning.

Other benefits include spherical end bearer details with no eccentricity, offering 5° pivot angles in any plane to provide on-site tolerance and cradled prop stabilisers, which allow props to be stacked directly above one another when being transported, optimising possible loads.
Customised options that cover burn-out packs, weldable stub ends, cast-in bolted shear plates with weldable prop connections and cast-in shear stubs are also now available.
On the face of it then, the longer a job lasts, the more economical structural steel becomes. However, aspects such as load capabilities and skilled labour, can have a big impact on choice, with ground shoring systems presenting a more attractive proposition to contractors in many instances.

In addition, early engagement with a specialist ground shoring provider can often create surprising savings. The key to a successful basement excavation project is often partnering with a specialist contractor early in the project process, so that they can help advise on the best support system available for the excavation in question.

The latest digital innovations can help bring projects to life from the earliest planning stages. For example, RMD Kwikform has combined its CAD and Locus AutoCAD software with its 3D visualisation software, LocusEye. The result? Unrivalled usability, so contractors can clearly understand how ground support systems will aid a project, with highly realistic 3D models rendered to see how a solution will look on site.

To download the new report from RMD Kwikform,
‘High-rise Construction: Driving Safety & Productivity’, please visit
www.rmdkwikform.com/systems/high-rise-construction

Denise Maguire        
Editor of Irish Construction Industry Magazine

Email: denise@mcdmedia.ie