Papers by Author: Peng Zhang

Abstract: Based on the the self-developed prestressed CFRP plate anchorage,the test specimens comprised 5 RC beams strengthened with the way the external prestressed CFRP plates,the research on the different prestressed tension and different span beam about the influence of the bending capacity , ultimate bearing capacity,cross section strain, CFRP strain and deflection of the test reinforced beams on the research. The test results showed that: the externally prestressed CFRP plate can obviously increase of the flexural performance of RC beams, and improve the utilization rate of the strength of the CFRP plate, through the external prestressed anchor of CFRP plate for a tension, reducing the RC beams crack, and improving the ductility of the RC beams.

Abstract: For reinforced concrete beams strengthened with prestressed carbon fiber reinforced polymer (CFRP) plates, design methods are derived for determining the allowable plate area or initial tension control stress of CFRP plate to achieve a targeted value of ductility. The derivation of equilibrium and compatibility equations for a rectangular cross section is presented. Base on the test of 2 reinforced concrete beams strengthened with prestressed CFRP plates, analytical results are compared with experimental results. Comparisons show that the design methods have good applicability. It can provide a reference for engineering application of strengthening design.

Abstract: Concrete is a three-phase material consisting of cement paste matrix, discrete inclusions of sand (aggregate), and an interfacial transition zone (ITZ) between the matrix and the inclusions. In order to calculate the elastic properties of the ITZ of cement mortar, We model the material as a composite formed by a matrix with embedded spherical particles; each surrounded by a concentric spherical shell. With help of the generalized self-consistent method (GSCM), equations of bulk modulus and shear modulus of ITZ are deduced, and Elastic properties of ITZ are computed by using experimentally known elastic properties of the composite. It is found that the shear modulus of ITZ is about 50% of that of the cement paste matrix.

Abstract: External bonding of fibre reinforced polymer (FRP) composites has become a common way for strengthening concrete members. The performance of the interface between FRP and concrete is one of the key factors affecting the behaviour of the strengthened structure. For this FRP-concrete structure, there are two types of debonding failures: plate end debonding and intermediate crack (IC) induced debonding. This paper presents an analytical solution for the second type debonding failures in FRP-concrete bonded joint model where the FRP plate is subject to tension at both ends. Both the strengthened beam and strengthening FRP are modeled as two linearly elastic Euler–Bernoulli beams bonded together through a thin adhesive layer. The debonding process of the FRP–concrete interface is discussed in detail, and closed-form solutions of bond slip, interface shear stress, and axial force of FRP in different stages are obtained. Parametric studies are further carried out to investigate the effect of the thickness of adhesive layer on the bond behavior of FRP–concrete interface.