The BKHS design team recently went above and beyond to provide expert advice to support the development of an innovative solution to meet stringent client requirements.

Here you can see fantastic examples of composite action achieved on two recent projects, where our specialised team of Structural Engineers demonstrated their timber expertise by facilitating long-spanning cross laminated timber and concrete panels to suit a complex beam layout.

To achieve this longer slab span, with a very wide beam spacing, a stiffer slab system was required. For both projects a timber-concrete solution was developed, with timber working compositely with a concrete pour above to meet the challenge.

Composite action is achieved when the CLT and the concrete are fixed together so they work as one component, rather than working separately. Concrete working in unison with timber provides a stiffer solution than timber panels alone, meaning thin CLT panels can achieve longer spans with increased structural efficiency. The high density of the concrete layer also improves vibration performance and mitigates the need for additional beams to support shorter panel lengths.

Two different composite systems can be seen here: an angled onsite screw solution, where screws were manually fixed to the CLT on site at angles, and a prefabricated ‘notched’ system - where areas of the timber were precision-fabricated with grooves ready to be flooded with concrete on site, allowing both materials to work as one.

In one of the projects, the BKHS design team were able to provide early advice on the advantages of the systems, including slimmer floor plates and fire protection benefits, supporting the project engineer throughout the PCSA stage, whilst also assessing the challenges. Complex analysis on the level of fixity of the connections between the two materials was essential and has ultimately contributed to future composite action R&D between timber, concrete and steel.

Key challenges on site included additional health and safety considerations, and temporary propping requirements for one of the projects, due to the curing required for the concrete; however, strong collaboration and pre-planning from design to delivery ensured a safe and speedy erection phase, where both projects were delivered to the highest quality.

Close attention to moisture management is always good practice in timber construction, but for the notched composite action solution in particular this was crucial. BKHS developed and observed a strict moisture management plan, including regular testing and monitoring while on site, and communicating potential risks to follow-on works. While additional fabrication hours were required for the complex notched system, on site works were less intensive than for the angled screw system, and both systems benefit from the lightweight advantages of engineered timber.

Overall, the system had a lower carbon impact than a full-concrete solution and demonstrates another advantage of hybrid construction.

_______________________________________

B&K Hybrid Solutions are experts in the design and delivery of structural steelwork and timber-steel hybrid projects. Our longstanding experience and specialist expertise has allowed us to work on increasingly innovative and sustainable developments across a wide range of sectors. Our aim is to bring the benefits of low carbon construction to the mass market, and the acquisition of our state-of-the-art steel manufacturing facility giving clients increased assurances through in-house supply. We are committed to helping clients cut cost, programme time, and carbon emissions, through innovative hybrid solutions.

Speak to a member of our team today:

[email protected] | 01332 957270 | www.bkhybridsolutions.co.uk 

Back to News
Date
17/01/2025
Category
Our Expertise
Article Author
B&K Hybrid Solutions

Download file

Please enter your details below to download the file.