Internal and External Teamwork is the Answer to Successful Design

05 Apr

Andrew Lowe is head of engineering design with specialist construction services supplier Groundforce.

He graduated from the University of Bristol with a Master’s degree in Civil Engineering that included study in continental Europe (Italy) and then worked for five years in civil and structural consultancies in Manchester, on residential, educational, leisure and commercial building projects. Towards the end of this time he gained Chartered status with the Institution of Structural Engineers.

The economic downturn in 2008 and subsequent reduction in new-build activity encouraged him to move into temporary works, becoming a project engineer for a European modular bridging and temporary works solutions supplier. In the following years he was promoted to senior engineer and then project team leader and became a member of the ICE.

He then joined an excavation safety systems supplier as principal engineer and was promoted within six months to design manager. During this time, he became a Chartered Manager (CMgr MCMI).

He joined Groundforce as head of engineering design in June 2017, with responsibility for managing the overall performance of the technical department and for all design output for UK teams (core shoring and major projects), some 4,500 new designs every year (and that does not include revisions!).

Andrew also acts as supervising civil engineer for engineers on the company-approved training scheme.

So, with all this experience and after 18 months in the job, NATM magazine asked him the following:

Q. What are the challenges that face design/technical teams and how are they dealt with?

A. Probably the biggest challenge at the moment, and one that has persisted over quite a few years, is finding, recruiting and keeping good engineers. We combat this by developing good relationships with universities through industrial mentoring/advising, by student placements and sponsorship, and offering an ICE CATS which is a big draw for many graduates. Once we get them on board we keep them motivated by offering challenging and varied work such as day-to-day design and checking, development work (like creating new design tools), site visits and presentations. It’s a dynamic, high-energy workplace.

Another major challenge for technical teams is delivering safe, efficient, high-quality, economic temporary works designs to tight deadlines but the trick to countering this is simply team work, clear expectations and good communication, supported by efficient systems and standardisation of presentation.

Q. To what extent is load monitoring being used and is there scope for it to become more advanced?

A. There is scope for a much greater use of load monitoring system particularly on major projects. However, the customer/geotechnical engineer would have to be more optimistic with their initial design to gain any kind of commercial or time-saving advantage from using it. There still appears to be a reluctance within the industry to use true observational methods to save on temporary works. Perhaps these will be adopted more widely in future.

Load monitoring systems are continually advancing and there is scope for them to advance further and integrate into 3D models.


Q. How do you find working with Eurocodes?

A. There is ongoing debate within the industry regarding the use and applicability of Eurocodes for temporary works which have traditionally been designed using a variety of British Standards (both permissible stress and limit state design) and supporting guidance produced by a variety of bodies such as CIRIA and British Steel.

The Temporary Works Forum has produced some excellent guidance on the use of Eurocodes for temporary works design. This has mostly been directed towards the design of falsework although there is also some applicability to the design of ground shoring equipment. The TWF guidance gives the designer the scope to use other appropriate methods.

We continually review, and contribute to, industry guidance to ensure we are designing in accordance with best practice and approved methods. We have developed methods of designing excavations and the associated support equipment which have ensured our solutions are safe and robust whilst at the same time being economic and competitive.

For excavation support, there are two aspects that must be considered - the geotechnical wall design and the structural framing/propping design.

Geotechnical wall design

For temporary works, there is limited guidance on the design of excavation support to Eurocode and as such it is the job of the designer to select an appropriate method based on the specifics of the scheme and their experience.

CIRIA 780 provides complete guidance on embedded retaining walls, along with a well-defined procedure for design of these structures to Eurocode. However, this is more focussed on deeper excavations with large sheet toe-ins. Many of the solutions we provide for shallower excavations, typical for utility work, are based on no-toe solutions so the guidance is not fully applicable in these situations.

Generally, for core shoring schemes, we use well-established methods such as the Piling Handbook Net Pressure method and Burland Potts method set out in CIRIA SP95.These approaches have been highly successful over the years. Often on core shoring schemes, due to the short procurement and design process, information regarding the ground conditions can be limited so the guidance recommends that a moderately conservative approach is taken.

Given the often limited information on the ground, it’s generally not appropriate to design to EC7 and carry out multiple analysis to the various design combinations. The limited, imprecise nature of the input data removes any accuracy from the analysis. Where accurate, reliable EC compliant SI is provided, a full EC7 design can be carried out if required, although any benefit gained from this approach over traditional methods is usually negligible. In my opinion, there does not appear to be any good reason to move away from the well-established, simpler, successful methods.

For major projects, the design of the wall is usually carried out by an external geotechnical specialist. In these instances, the wall designers should have high quality SI on which to base their design. It therefore becomes sensible to use a Eurocode design methodology.

Structural framing/propping design

Traditionally, our equipment was designed to BS 5950 with appropriate safety factors applied. However, we have now carried out structural verification calculations to EC3 (BS EN 1993) for the vast majority of our equipment. The values in our Technical File include overall factors of safety and are presented as Working Load Limits (WLL) or Allowable Loads. These concepts, along with Safe Working Load (SWL) are familiar, well-understood concepts within the industry, both at site and engineering office level.

For ease and efficiency in the design process when designing core shoring schemes, we carry out checks to ensure the load on the equipment doesn’t exceed the factored values in the Technical File. This ensures we can be confident the equipment does not become overloaded as a result of “small” changes on site.

For major projects, we take a different approach to the design of the propping equipment. Following analysis, we carry out Eurocode structural checks on the props and walers, taking into consideration the various actions (earth, self-weight, accidental, thermal) and combinations. This enables us to design large propping schemes efficiently but comprehensively.

Probably more important than whether or not to design to Eurocode is that the principles of BS 5975 are followed. For any element of temporary works it is essential that a full and complete design brief is provided to the designer, the design is properly checked and that there are people (TWC/TWS) and systems in place to ensure the temporary works are built correctly.

Historically, where failures do occur, it is as a result of incorrect or incomplete information provided in the design brief, poor installation, or the contractor not following the design, NOT as a result of designing or not designing to Eurocodes.

Q. What should the industry be doing more/less of?

A. I don’t know that there is anything we should be doing less of! But we should be doing more to encourage young people to take up roles in engineering, then giving them comprehensive training and guidance so we can develop them to be tomorrow’s leaders. We should be increasing awareness of temporary works among permanent works designers. And particularly, we should be encouraging consultants and contractors to work more collaboratively with the supply chain as the early involvement and appointment of suppliers and sub-contractors to provide advice ultimately produces time and money savings.