Structural performance of a hybrid FRP composite – lightweight concrete bridge girder

Abstract

A novel hybrid fibre-reinforced polymer (FRP) composite – lightweight concrete (LWC) girder was developed and implemented in a bridge superstructure as a result of the comprehensive R&D project. The new bridge system is intended to have durable, structurally sound, lightweight, and cost effective hybrid FRP/LWC girders that will take full advantage of inherent and complementary properties of composites and lightweight concrete. The proposed hybrid girder consists of a FRP shell with trapezoidal cross-section and a lightweight concrete slab, reinforced with glass fibre-reinforced polymer (GFRP) rebars and acting compositely with the shell. Before implementation, a test specimen fabricated as a full-scale model of prototype bridge girder was subjected to a series of quasi-static and fatigue loading tests. This paper presents the selected results of research on evaluation of stiffness, strength, ultimate capacity, and global factors of safety against failure. The test results were compared to the performance criteria formulated in the relevant bridge standards. The output of research confirmed that the proposed hybrid bridge girder has an excellent performance from the structural engineering point of view, and fulfils the appropriate standard conditions to be implemented in an actual bridge. Moreover, due to quite high safety factors it seems to be possible to optimize the hybrid girder design by reducing the amount of FRP material required.