Author: T. Gould (Vp plc Groundforce Shorco)
1 February 2017
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T. Gould (Vp plc Groundforce Shorco)
Nowadays in the UK, the majority of below-ground temporary works support is undertaken using proprietary equipment, provided on a rental basis by specialist suppliers. Over the last 30 years, the scope
of proprietary equipment has increased dramatically. In the 1980s, proprietary equipment was limited to shoring up pipe trenches and small-scale pits, which were supported with hydraulically operated aluminium waler frames or the ubiquitous manhole brace. Today, there is a huge range of equipment available to support all sizes of trench, shaft and coff erdam. It is not uncommon to see modular hydraulic struts clear-spanning over 40m.
In the second of two articles examining temporary works failures, Director of Structural-Safety, Alastair Soane, considers why failures occur and what steps can be taken to reduce the risk of catastrophic events.
The majestic splendour of the Millau Viaduct, towering 343m above the Tarn valley in southern France, will inspire engineers for generations to come. Emulating such feats of engineering requires an understanding of buckling beyond the simple Euler formulae for pin-ended struts, as well as the services of a celebrated architect to fine-tune the proportions and sculpt the shape and details of the extraordinary pier supports. Exceptionally tall or slender columns may necessitate finite-element (FE) modelling to determine the effects of buckling. However, in many cases, an accurate assessment of the critical buckling load can be made by hand calculations incorporating spring supports or tapered/stepped stiffness columns. This paper discusses the calculation of the buckling load for the end conditions given in Eurocode 2 (EC2), Figure 5.7, including various rotational spring restraints and variable stiffness within the length of the strut.
The permanent works designer (PWD) has a major influence on the temporary works and can, for example: eliminate temporary works, e.g. through the use of steel decking rather than timber falsework minimise the use of temporary works, e.g. by using the permanent capping beam as a waling in basement construction design the permanent works so that simple temporary works solutions can be used.