Q&A: Paul Callum - Bligh Tanner

Paul Callum is a Partner and Principal Structural Engineer at Bligh Tanner - an innovative structural, civil, environmental and water engineering consultancy based in Brisbane.  Paul - a valued panellist at a recent CityShapers event - shares his insights into how developers can create more cost effective and sustainable built solutions. 

What are five key ways good structural design can save on construction costs?
Influencing the project design early in the design process and before the form and layout gets locked down;Considering construction constraints and likely construction methodology. Experience is the key here especially if a contractor has not yet been appointed; Reviewing all forms of prefabrication especially on sites with poor access or little lay down space. Prefabrication can assist in minimising construction time and improving quality; Designing with cost and availability of materials, construction equipment and contractor expertise in mind. These items change from year to year and with location, as well as with a contractor’s abilities and access to each of these. Advising on temporary works and construction methodologies given the designer’s familiarity with the capacity of the structure.
What are some of the biggest mistakes you see developers make and how can these be mitigated?

Bringing the design team in late in the process is a big one. The opportunity to influence the design and maximise value to a project is greatly reduced as the process proceeds, the design elements get locked in and flexibility to investigate better designs reduces. Ensure that an experienced expert in each design discipline is consulted early to ensure that the design development process does not take the design irretrievably off the rails.

Allowing engineering disciplines to be represented at the table by non-specialists in that field. It can be a significant issue to either not have a specialist team member at the table especially during the schematic design stage but equally disruptive to have a multi-discipline team represented by one individual whose constant response is “I’ll get back to you”. The developer needs to insist that an expert from each discipline is ‘at the table’ especially during the development stage. This might relax during documentation but it is critical during the preliminary stages.

Having a client representative who has a poor understanding of the design process. This can be catastrophic as a knowledgeable client rep’ is critical to getting the most from a design team by clearly articulating the client’s needs.

Letting the design team lead the process by their experience instead of the client’s goals. Far better to challenge the team by asking for what the client really desires rather than by asking the team for what they can deliver.
What are some structural solutions to creating more environmentally sustainable developments?
The obvious is to produce a good design that achieves a good functional building that will be useable and valuable for as long as possible – demolishing and replacing a building due to lack of flexibility, aesthetic, durability or just high operation costs is an incredible waste of resources.

Other solutions include:

• Adaptive Re-Use : Making the most of the existing and extending the life of existing buildings;

• Maximising prefabrication to minimise material usage, waste and delivery travel. Prefabrication reduces the need for a more specialised workforce at each work site and significantly reduces travel time in the production of the finished element e.g. a precast floor removes the need to separately deliver concrete, pumps, formwork, reinforcement, concreter teams, etc. These benefits in turn improve site safety by reduced numbers and activities on site as well as the sustainability of the construction process.

• Using recycled material. This is typically reinforcement and occasionally aggregates but the re-use of existing materials already on site (depending on the project of course) is valuable e.g. The use of second hand timbers - as we used on Tree of Knowledge project (tonnes of ex hardwood power poles);

• The use of new materials such as geopolymer concrete, thermoplastic structural elements, Mass Timber such as Cross Laminated Timber (CLT) is slowly making inroads into the Australian market (albeit only in imported material at the moment).

Bligh Tanner has won national awards for innovation - what are some of the firm's standout innovations to date?
The world-first use of modern structural geopolymer concrete in the $32M Global Change Institute Building at University of Queensland is a major innovation. It has the potential to be an absolute game changer in construction in the future.

Bligh Tanner’s water harvesting systems such as Rain Bank at Southbank and the FiSH and Potaroo at Fitzgibbon Chase, have also been recognised nationally and internationally as setting new benchmarks for creating water sensitive cities.
You have led structural engineering on major projects up to $500M over your 30 year career- what has been the most memorable project you've worked on to date and why?
There have been many wonderful projects that I have been involved in, from the $500M Hong Kong Central Station Development and $200M Brisbane Convention and Exhibition Centre (as a Principal with Arup), to complex art installations for the Gallery of Modern Art.

One of the most satisfying projects was the Tree of Knowledge Memorial in Barcaldine. Its remote location necessitated that prefabrication was extensively employed and that the building’s form and detailing was sensitive to the aesthetic intent of the architect (m3architecture). The detailing of the structure to hang over 3,600 pieces of 1.8 m long timbers securely from the roof structure was well received. Simple detailing such as the use of square hangers through square holes punched in the tube battens to prevent rotation, allowed rooftop access and adjustability, as well as security with the use of locknuts.

My current challenge is leading the structural team on the $110 M Carrara Sports Precinct.
What is the latest game changer in structural design?
Materials –

• Geopolymer Concrete

• Mass Timber

• Composites – investigating the use of thermoplastics as structural elements. Pultrusion is an exciting field that has the potential to replace steel in highly corrosive environments and also allow the design of boutique structural elements with almost any shape – a bit like 3D printing of structure

• Prefabrication