Short-term flexural behaviour of concrete filled pultruded GFRP cellular and tubular sections with pin-eye connections for modular retaining wall construction

A retaining wall system modularly assembled from pultruded glass fibre reinforced polymer (GFRP) sections filled with concrete is introduced in this paper. Two main components (i.e., plank and pile) of the modular system are investigated experimentally at different spans under four-point bending to understand different failure modes. The effect of concrete filling, infill concrete modulus, and section shape (round and square), section size (300-600 mm) and spacing (0-600 mm) are studied through validated finite element modelling and results are compared with the existing reinforced concrete solution. Results show that the concrete filling increases the bending stiffness and prevents premature local crushing, tendency of ovalisation and local buckling by providing lateral supports to GFRP walls. Depending on pile spacing, the square pile deflects 7-13% less than the round pile with equivalent cross-sectional area. It has been found that the existing concrete pile may be replaced by a similar size of concrete filled GFRP pile for comparable performance in terms of stiffness.