Structural Performance of Smart CFRP-FBG Reinforced Steel Beams

Many beam structures suffer from gradual performance degradation with the increase of service life. To recover the bearing capacity of these beams, carbon fiber reinforced polymer (CFRP) plates are developed to attached on the beam bottom. To check the structural performance of the CFRP reinforced beams, smart CFRP plate with FBGs in series is designed and LVDTs are adopted to measure the deformations. The deflection of the reinforced beam is given based on the elastic conversion cross-section method. The experimental results validate the effectiveness of the proposed algorithm. The study shows that the CFRP reinforced zone has a larger flexural rigidity than the pure steel beam zone. The general distribution of the deflection along the span of the CFRP reinforced beam can be described by the proposed formula. It provides a scientific design guidance for the deflection control of CFRP reinforced structures

Interfacial Interaction of CFRP Reinforced Steel Beam Structures

Due to the increase of service life, the phenomenon of performance degradation of bridge structures becomes more and more common. It is important to strengthen the bridge structures so as to restore the resistance level and extend the normal service life. Carbon fiber reinforced polymer (CFRP) materials are thus used for the assembly reinforcement of bridges for the advantages of high strength, light weight, corrosion resistance and long-term stability of physical and chemical properties, etc. In view of this, based on the previous theoretical study and the established formula of the interfacial shear stress of CFRP reinforced steel beam and the normal stress of CFRP plate, this paper discusses the sensitive parameters that affect the interfacial interaction of CFRP strengthened beam structures. Through the analysis, the priority design indicators and suggestions are accordingly given for the design of reinforced beam structures. Young’s modulus of CFRP composite and shear modulus of the adhesive have the greatest influence on the interfacial interaction, which should be carefully considered. It is suggested that CFRP material with Ec close to 300 GPa and thickness no less than 3 mm, and adhesive material with Ga less than 5 GPa and 3-mm thickness can be adopted in CFRP reinforced steel beam. The conclusions of this paper can provide guidance for the interfacial damage control of CFRP reinforced steel beam structures