Design Methodology

Our Approach to Propping Design

All Groundforce struts are designed to comply with the resistance requirements set out in EN1993. Checks are made for the local resistance of all components such as swivel pins, bearing plates and flanged connections. A global resistance is calculated to take into account the effects of lateral loading and buckling. These are dependent upon the overall length of each strut and various other application specifi c load requirements, as indicated in the diagram below. This tailored approach ensures that every detail of every strut is safe and supported by comprehensive calculation and testing.

As well as ensuring adequate resistance of the equipment to EN1993, all Groundforce designs are carefully engineered to meet the load requirements set out in EN1990, EN1991, and EN1997. By applying the appropriate combinations of actions and effects, Groundforce engineers aim to provide economical solutions that do not compromise on safety

• Applying EN1990 load combinations produces safe and economical designs  
• EN1993 partial factors applied to give critical components a higher Factor of Safety (FOS)  
• National annexes applied to European designs
• Safety and survivability included for a variety of accidental situations                            

                                

Pre-Loading

Pre-loading of struts is a necessity in almost all propping systems. This has a twofold benefi t. Initially to take out the “slack” in a system, secondly to reduce potential wall defl ection. One of the major benefi ts of hydraulic struts is the built-in ram that allows very fast installation and pre-load with virtually no additional time or equipment requirements.

All struts will compress under load, hydraulic struts more so than traditional steel props. It is often a requirement that hydraulic struts are pre-loaded signifi cantly more at the installation stage compared to their steel counterparts. This will reduce the displacement of the excavation walls during the construction phase. Applying too much pre-load can increase strut loads, requiring bigger struts and becoming uneconomical. It is important that pre-loaded struts are carefully designed to achieve the most economical solution.
 

Benefits of Proprietary Hydraulic Propping

• Speed – signifi cant time savings are achievable compared to a traditional structural steel solution
• Delivery on demand – equipment can be supplied to suit your procurement strategy, reducing on-site storage requirements
• Flexibility – all struts have integral hydraulic jacks with up to 1.1m stroke providing a wide working range
• Sustainability – modular systems remove steel waste associated with fabricated systems
• Safety – minimal hot-works (welding) required on site

Initial Design Information

In order to put forward a highly accurate, technical and cost-effective solution to meet your temporary propping requirements, a detailed design brief is essential, covering the following:

• Drawings – PDF essential. CAD dwg or Revit model preferable
• Loadings – temporary kN/m line loads (SLS/ULS)
• Design Criteria – stiffness and defl ection requirements
• Site Constraints – maximum lift capacity and permanent works that are to be considered
• Program – start date and anticipated hire durations

Groundforce will work alongside you to build an initial commercial and technical submission. It may be possible to value engineer this solution upon supply of all relevant information