It considers how the requirements for fabrication and erection of the structure can be addressed to ensure value-for-money outcomes for the construction phase and the constructed facility.
Design for construction considers at least the following aspects:
Design to facilitate the efficient construction of a project
Design for economy
Design to facilitate better safety outcomes during construction
The potential for prefabrication and modularisation
Designers have a primary role to play in ensuring safe, compliant outcomes for our constructed infrastructure, both during construction and with the completed facility.
Prevention through design (PtD), also called safety in design (SiD) in Australia, is the concept of applying methods to minimise occupational hazards early in the design process, with an emphasis on optimising the health and safety of users throughout the life cycle of materials and processes.
It is a concept and movement that encourages construction or product designers to ‘design out’ health and safety risks during design development. The concept supports the view that along with quality, programme and cost, safety is determined during the design stage. It increases the cost-effectiveness of enhancements to workplace safety and health.
Enhancements to safety outcomes can be facilitated by:
prefabrication and/or modularisation to minimise labour and time involved in connections on site
incorporating erection sequencing into 3D Building Information Models and providing graphical representation of the erection sequencing. The ‘Erection Sequence Methodology’ provides an easy-to-interpret ‘manual’ for the steelwork erectors and eliminates confusion, particularly for higher-risk projects
design-bolted and site-welded connections in easily accessible places and where possible – for example, column splices within working height of floor level
designing access ladders into structures to aid on-site installation
designing holes or tabs to connect safety lines
guide plates to assist with temporary alignment of connections before bolting up
minimum four-bolt connections in column baseplates to facilitate stability during erection
utilising bolts for field connections, in preference to welds. Bolted connections are immediately stable with limited bolts in place
avoiding sharp corners with steel details as these can cause injury
simplifying connections and providing enough space for assembly.
The diagram below indicates a suggested phasing for incorporating PtD into the design process:
The Safe Design of Structures Code of Practice sits under the harmonised Work, Health and Safety Act 2011 and provides specific and practical guidance to stakeholders involved in the design of a building or structure as to how to implement the requirements of the Act.
It highlights the significant shared responsibility for safe outcomes placed on all stakeholders, not just designers. Clients, manufacturers, importers, suppliers and constructors all have a duty of care to ensure safe compliant outcomes. The engineer should inform these parties of their responsibilities in this regard.
The free ASI publication ‘Practical guide to planning the safe erection of steel structures' (PDF) is intended for any person involved with the design, coordination, fabrication or erection of multi-element steel structures and is intended to apply to all types of projects, providing a framework for the user to determine what steps are appropriate for their particular scope of work.
In relation to structural steelwork, ‘constructability’ refers to how easily, efficiently and safely steel framing can be erected on site, allowing also for interfaces to other construction on site, including foundations and supporting structures, building envelope, in-situ concrete for floors, mechanical and electrical installation and the like.
Effective constructability is a combination of:
member configuration to minimise piece count for assembly on site
location and type of connections, to ease site assembly
consideration of the extent of potential prefabrication and/or modularisation to minimise site assembly
the construction methodology, which may in turn influence or modify the design outcomes.
Given the structural steelwork erector may not always be known at the time of the primary design phase, it is important that designers are cognisant of typical current erection methodologies and factor this into the design approach. Designers should also be open to modifications to the design, particularly as part of a value engineering exercise.
Prefabrication is well entrenched as standard practice for the structural steel solution. However, every project is generally bespoke and therefore there is always the potential for the engineer to work with the constructor to rationalise the most effective approach to prefabrication for the particular project and proposed erection methodology. In this regard, early engagement between project stakeholders is desirable.
Modular construction – the use of ‘volumetric modular’ units in particular – is an area of current significant innovation, both for mid-rise construction and multi-level buildings, particularly for accommodation facilities such as apartments, hotels and student accommodation that can take advantage of inherent repetitious topology.
Innovation in construction of steel structures occurs regularly, responding in particular to the bespoke nature of projects and competitive pressures. Across the various stakeholders in the supply chain, digital construction has resulted in significant improvements in speed to market and quality, together with minimised rework.