PhD Studentship: Durability performance of connections with screws in mass timber construction

Supervisor’s Name: Eleni Toumpanaki

Scholarship start date: March 2025

Latest start date: September 2025

The Net Zero emissions commitment of most countries by 2050 has renewed an interest towards timber buildings. The use of mass timber has increased considerably in the UK in the past 15 years mainly for multi-storey residential buildings. Despite this surge in timber, further advances in the sector are hindered by high insurance costs related to uncertainties due to fire and moisture-induced degradation. Water leaks occur more frequently than fire as identified by the RISCAUthority, and incidents of timber damage from biodegradation are increasingly being reported. These are mostly related to trapped moisture between impervious membranes (e.g., waterproofing) and timber and water leaks from pipes.

Changes in moisture content can also result in reduced structural performance at the connectivity level. Swelling/shrinkage effects upon sudden changes in relative humidity can often lead to cracks. Rigid metal elements (e.g., angle bracket connections) can cause high internal stresses due to swelling restriction when timber is left exposed to rainfall during the construction stage. These high internal stresses often lead to withdrawal failure of screws.

This research project will study the performance of timber connections with screws in both glue laminated and cross laminated timber due to hygrothermal effects. An experimental programme will be conducted to assess the load capacity and stiffness of screw connections. The experiments will range from small-scale testing of single connectors to medium-scale testing at the connectivity level. Of interest is to simulate specific moisture/loading histories as identified on site and during the operational life of a timber building. An extensive Finite Element (FE) modelling programme will be conducted to help interpret experimental results and identify the unknown diffusion and mechanosorptive material parameters of timber.

The project seeks to inform current design guidelines and technical specifications on the load capacity of timber screw connections accounting for the presence of moisture in collaboration with Rothoblaas.

Applicants must hold/achieve a minimum of a merit at master’s degree level (or international equivalent) in a science/civil/mechanical/architectural engineering discipline. Applicants without a master's qualification may be considered on an exceptional basis, provided they hold a first-class undergraduate degree. Please note, acceptance will also depend on evidence of readiness to pursue a research degree.

Applicants should have:

• Strong interest in both experimental and numerical work
•  Capacity to work independently and be keen to conduct high quality research
•  Excellent written and oral communication and presentation skills
•  Interest in working with industrial partners

If English is not your first language, you need to meet this profile level:

Profile E

Further information about English language requirements and profile levels.

Prior to submitting an online application, you will need to contact the project supervisor to discuss.

Online applications are made at http://www.bris.ac.uk/pg-howtoapply. Please select #programme title# on the Programme Choice page. You will be prompted to enter details of the studentship in the Funding and Research Details sections of the form.

For questions about the research topic, please contact:

Dr Eleni Toumpanaki at eleni.toumpanaki@bristol.ac.uk.

For questions about eligibility and the application process please contact:

Engineering Postgraduate Research Admissions admissions-engpgr@bristol.ac.uk

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