Development of a modular and flexible construction system for a self-supporting and modular bridge formwork made of fibre-reinforced plastics
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Zhikun Yang (GERMANY), Christian LAUTER (GERMANY)Abstract :
Abstract and introduction
This work aims to develop a self-supporting, modular formwork system (based on 4-5 basic elements) predominantly made of glass fibre reinforced plastic (GFRP) materials to build longer-life bridges more efficiently. This formwork will act as the external surface of the future concrete structure and will not be removed after the concrete has been poured and hardened.
GFRP can be used to produce large continuous profiles through automated pultrusion moulding processes with high strength and stiffness. Additionally, GFRP is highly resistant to corrosion and UV, making it an excellent option for permanent protecting the exterior surfaces of bridges.
Experimental investigations
Standard 6 mm GFRP Double-T profiles from GFRP manufacturer Fiberline Building Profiles A/S were selected for the material tests. In four-point bending (4PB) tests was determined that the axial flexural modulus (Ea,f) of the profile bar area is around 19 GPa and of the top and bottom edge can reach 28 GPa. In the transverse direction is flexural modulus (Et,f) lower and around 14 GPa. Based on this test result, the connection points were arranged at the top and bottom edges of the profile in modular construction in order to achieve optimum connection and load effects. The bar area will serve as a potential weak point of the profile and will be used as an orientation and theoretical basis for optimising the formwork. FEM static analysis of the GFRP bridge formwork demonstrated sufficient load capacity and deflection of less than 1/250 of the bridge's clear span, as required by the construction industry.
A preliminary investigation was conducted on the bond between concrete and GFRP using an GOM ARAMIS measuring system in three-point bending (3PB) tests. The deformation of the composite structure surface is mainly concentrated in the bonding area, which is less than 0,3% before cracks appeared. There is a relative axial slip between concrete and GFRP. The maximum slip before cracks appeared was 7 µm. These findings are then used in the subsequent of the study to establish a stable connection.
Conclusion and outlook
This research demonstrates the feasibility of large continuous profiles produced by an automated pultrusion process as a bridge formwork. In addition to sufficient load-bearing capacity compared to traditional formwork, GRP formwork can be used as permanent formwork to protect the concrete from environmental damage. Subsequent research will investigate methods for establishing permanent and stable connections between concrete and GFRP profile surfaces. Ultimately, in future construction, the formwork system and cured concrete will share the load-bearing function of the bridge. This combination allows for achieving the load-bearing capacity of conventional bridges, reducing the investment for concrete and reinforcement, and possibly dispensing with the use of reinforcement altogether.
This work aims to develop a self-supporting, modular formwork system (based on 4-5 basic elements) predominantly made of glass fibre reinforced plastic (GFRP) materials to build longer-life bridges more efficiently. This formwork will act as the external surface of the future concrete structure and will not be removed after the concrete has been poured and hardened.
GFRP can be used to produce large continuous profiles through automated pultrusion moulding processes with high strength and stiffness. Additionally, GFRP is highly resistant to corrosion and UV, making it an excellent option for permanent protecting the exterior surfaces of bridges.
Experimental investigations
Standard 6 mm GFRP Double-T profiles from GFRP manufacturer Fiberline Building Profiles A/S were selected for the material tests. In four-point bending (4PB) tests was determined that the axial flexural modulus (Ea,f) of the profile bar area is around 19 GPa and of the top and bottom edge can reach 28 GPa. In the transverse direction is flexural modulus (Et,f) lower and around 14 GPa. Based on this test result, the connection points were arranged at the top and bottom edges of the profile in modular construction in order to achieve optimum connection and load effects. The bar area will serve as a potential weak point of the profile and will be used as an orientation and theoretical basis for optimising the formwork. FEM static analysis of the GFRP bridge formwork demonstrated sufficient load capacity and deflection of less than 1/250 of the bridge's clear span, as required by the construction industry.
A preliminary investigation was conducted on the bond between concrete and GFRP using an GOM ARAMIS measuring system in three-point bending (3PB) tests. The deformation of the composite structure surface is mainly concentrated in the bonding area, which is less than 0,3% before cracks appeared. There is a relative axial slip between concrete and GFRP. The maximum slip before cracks appeared was 7 µm. These findings are then used in the subsequent of the study to establish a stable connection.
Conclusion and outlook
This research demonstrates the feasibility of large continuous profiles produced by an automated pultrusion process as a bridge formwork. In addition to sufficient load-bearing capacity compared to traditional formwork, GRP formwork can be used as permanent formwork to protect the concrete from environmental damage. Subsequent research will investigate methods for establishing permanent and stable connections between concrete and GFRP profile surfaces. Ultimately, in future construction, the formwork system and cured concrete will share the load-bearing function of the bridge. This combination allows for achieving the load-bearing capacity of conventional bridges, reducing the investment for concrete and reinforcement, and possibly dispensing with the use of reinforcement altogether.