Testing the strength of your steel and concrete knowledge
This week’s training session is on the Construction Technology and Environmental Services competency (T013). We’ll be looking in particular at steel and concrete frame construction. For this one, the RICS Requirements and Competencies guide says you need “a clear understanding of the design and construction processes commonly used in the industry”, plus in depth knowledge of construction solutions relevant to your projects. This is a core competence under the Construction and Quantity Surveying pathway that must be achieved to level 3.
An example of the type of question an assessor could ask at each level, and how it could be answered, is provided below.
Question Can you explain what a composite slab is and in what circumstances one may be used?
Answer Composite slabs consist of a profiled steel deck, acting as the permanent soffit, whist at the same time providing the formwork for insitu concrete in-fill. The concrete usually includes steel reinforcement to increase strength and reduce cracking. Composite slabs are principally for use with steel frames, although can also be supported on brick, masonry or concrete components.
Question What factors should be considered when choosing between a concrete or steel framing solution for a commercial office building?
Answer The frame solution for any building will depend upon a number of factors that should be taken into account to arrive at the most appropriate solution. The candidate may identify some of the following factors:
• Programme requirements may be a key consideration on a commercial building as typically steel is quicker to erect on site than concrete. However, this does need to be offset against a longer lead in period for steel currently.
• Requirement for column free spaces within the office.
• Complexity of design, with steel providing greater flexibility.
• Aesthetics and client aspirations.
• Repetitiveness of design. This will have a large impact on the cost of temporary works, such as formwork.
• Market conditions and supply costs.
• Height of building.
• The mechanical and electrical services strategy may impact, including service zones and whether the building itself is to be used for environmental control, e.g. concrete can provide thermal massing.
• Technical performance requirements of the building, including office floor loads, fire protection, etc.
• Site logistics, e.g. delivery of materials to site, on/ off site storage, plant restrictions, etc
Question From your record of experience, I see you recommended a steel frame on your project X. What approach did you take to be able to recommend this solution to your client?
Answer The reasons behind the choice of frame solution will depend on a number of factors as outlined within the level 2 answer. The assessors would be looking for the candidate to demonstrate their experience and competence through their approach. The frame solution will typically be a team recommendation and the candidate will also be demonstrating their ability to work within a team. The client’s objectives or the type of building may lead to a clear choice of frame solution, but where there are genuine options available, the candidate may approach the task through the following activities:
• Understand the client’s brief and key objectives
• Understand any site or project constraints that may favour one structural solution over another
• Consider any abnormals specific to the building
• Review with the design team the various structural options available for the building
• Consider and compare programmes for each of the options
• Prepare comparative cost estimates for each of the different options. This needs to take into account current market factors, as well the knock on effect to other elements, e.g. impact on foundation design and subsequent costs, façade areas impacted by storey heights, etc. Also the estimate needs to take into account other on-costs, including construction preliminaries, professional fees, inflation, etc.
• Identify and recommend the frame option that best meets the client’s objectives and brief, taking into account time, cost and design/ quality criteria. This could even lead to a part steel, part concrete frame building, or possibly use of composite construction.
• The candidate may then work with the design team to value engineer the design to deliver the most efficient building to meet the client’s needs.
A follow up question may be to ask the candidate why they made their recommendation? This will allow the candidate to expand further on some of the above issues in relation to their particular project, weighing up the advantages and disadvantages of each option.
Building's APC Trainer advice is intended as guidance only and should not replace your own study
By Dean Mills, director, Turner & Townsend Cost Management