Feasibility of strengthening glulam beams with prestressed basalt fibre reinforced polymers

With the relatively recent emergence of basalt fibre reinforced polymer products (BFRPs), the previously prohibitive issues to the introduction of FRP products to strengthen glulam beams initially seem to be addressed.

The main activity of Global Basalt Engineering LLC is creation of effective productions on release of continuous basalt fiber (СBF) with technologies of the last generation and composites on the basis of СBF (Basalt Fiber-Reinforced Polymer Composites as BFRP).

The current thesis is a pilot study of the feasibility of prestressing glulam beams with BFRP materials. The principal issues facing the introduction of prestressed BFRP products in glulam beams are addressed and analysed through laboratory testing, finite element analysis and a theoretical analysis.

From the observations and results   of these investigations, possible production methods are considered in order to attempt to develop a plausible manufacturing technique.

The aim of the laboratory testing and FE modelling was to examine the BFRP-adhesive-wood connection with various BFRP product and adhesive combinations. The expected results were: ultimate strength, failure mode and slippage of the connection. Unfortunately, no usable results could be obtained from laboratory tests due to premature failure of the BFRP materials.

The FE results show that out of all of the tested arrangements, the most appropriate was the fabric BFRP with PUR adhesive. However, the shear strength of the connection still proved to be fairly low, highlighting the need for a complicated variable prestressing solution with several small steps.

Based on current knowledge and technology, it was hypothesized that the most reasonable solution to actual production of glulam beams prestressed with BFRP products would best be performed with a variable radiation curing and prestressing system. Because this system is not currently developed, large investments and investigations would be presumably needed, and it is questionable whether potential benefits from such a product would outweigh the initial efforts to develop and implement an appropriate production system.

Though the results from a theoretical analysis prove that potential for glulam beam height reduction is great, it is obvious from the work of the present thesis that a large number of challenges still exist before glulam beams prestressed with BFRP products is feasible.

Master of Science Thesis in the Master’s Programme Structural Engineering and Building Performance Design
Zachary Christian, Kavan Shebli

Department of Civil and Environmental Engineering Division of Structural Engineering Steel and Timber Structures Chalmers University of Technology, Göteborg, Sweden

Countries: Sweden

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One Comment

  1. Basalt mesh was tested and made for concrete and not wood glulams. The investigators mistakenly tried to apply a material made specifically for another application assuming it would have the same properties. Basalt mesh can at times be undersaturated (resin deprived) sadly, and yes superior methods and sizings could be applied to have better results as suggested.

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