Nano reinforced cement and concrete composites and new perspective from graphene oxide

Strengthening of steel structures with fiber-reinforced polymer composites

This paper presents an experimental study on the behaviour of CFRP-to-steel bonded interfaces through the testing of a series of single-lap bonded joints. The parameters examined include the material properties and the thickness of the adhesive layer and the axial rigidity of the CFRP plate. The test results demonstrate that the bond strength of such bonded joints depends strongly on the interfacial fracture energy among other factors. Nonlinear adhesives with a lower elastic modulus but a larger strain capacity are shown to possess a much higher interfacial fracture energy than linear adhesives with a similar or even a higher tensile strength. The variation of the interfacial shear stress distribution in a bonded joint as the applied load increases clearly illustrates the existence of an effective bond length. The bond–slip curve is shown to have an approximately triangular shape for a linear adhesive but to have an approximately trapezoidal shape for a nonlinear adhesive, indicating the necessity of developing different forms of bond–slip models for different adhesives.

Experimental study on CFRP-to-steel bonded interfaces

Bond–slip models for double strap joints strengthened by CFRP

Experimental study of fatigue crack growth behaviour in adhesively reinforced steel structures

State-of-the-art review on FRP strengthened steel structures

Excavating tunnels in sandy cobble strata carries a high risk of ground collapse caused by instability of the tunnel face. In order to prevent instability at the tunnel face during excavation, this paper focuses on studying the effects of various pre-reinforcement method on the stability of tunnel in the sand-cobble strata. Firstly, pre-reinforcement projects suitable for these tunnels are proposed. Then, using FLAC3D to established numerical models, then simulate the excavation process under six different working conditions: non-reinforced, pre-reinforcement with advance small pipes, pre-reinforcement with pipe-roof, pre-reinforcement with GFRP bolts, pre-reinforcement with advance small pipes and GFRP bolts, and pre-reinforcement with pipe-roof and GFRP blots. The displacement and stress fields of the soil behind and in front of the tunnel face under each condition are obtained. The results show that the use of GFRP bolts for pre-reinforcement can effectively control the deformation of the surrounding rock in front and behind the tunnel face, and pre-reinforcement with advance small pipes or pipe-roof can reduce the settlement of the tunnel crown. Pre-reinforcement by the combination of GFRP bolts with advance small pipes or pipe-roof can better ensure the stability of the tunnel during the excavation process.

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Lei Zhang

Papers

State-of-the-art review on FRP strengthened steel structures

Stability analysis of tunnel in sandy cobble strata under different pre-reinforcement techniques