Experimental investigation of three-point bending behavior of assembled hybrid composite tubes before and after the fire endurance test

Abstract

This work presents an experimental investigation of the post-fire flexural strength of Filament-wound Glass Fiber Reinforced Polymer (GFRP) tubes manufactured by CTRA Company. These tubes are assembled according to both the NFT57-900 and DIN-16966 standards’ recommendations. To this end, flexural tests have been carried out on butt-to-butt assembled tubes, before and after fire endurance tests. To gain a better insight into fire-induced damage mechanisms, thermal analysis (DSC and TGA), FTIR analysis tests, as well as Scanning Electron Microscope (SEM) observations have been conducted. The experimental results revealed that a water leakage was observed prior to the recommended threshold time by the International Maritime Organization (IMO) resolution. It has been also confirmed that flexural properties of the GFRP tube are degraded after the fire tests. Furthermore, a quantitative comparison for both filament tubes assembled according to the NFT and DIN standards confirms that the NFT ones depict higher resistance. Finally, damage investigation reveals that the main observed forms of damage occurring during this experiments are delamination and matrix cracking phenomena. The main novelties of this work are (a) extending the classic analysis carried out on simple composite plate to cover water-filled GFRP assembled tubes subject to fire endurance test, and (b) the experimental investigation of DIN and NFT butt welded joined pipes under three point loading prior and post fire endurance test.