Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Civil and Environmental Engineering


Riyad Aboutaha

Subject Categories

Civil and Environmental Engineering | Civil Engineering | Engineering


Prestressed concrete (PC) bridge girders play an important role in highway bridges because of their embedded prestressing strands and low cost. They can provide adequate flexural strength depending on the integrity of the concrete-strand bond. However, highway bridges near industrial facilities are often subjected to heavy trucks. Under frequent overloads, the large deflections of bridge girders may induce deterioration of the bond between the strands and concrete at critical sections during bending, resulting in debonding of the strands in the most critical section region, over the span length. This study describes an in-depth analysis of the flexural strength of a strengthened AASHTO Type III girder-deck system with debonding-damaged strands based on the finite element software ABAQUS. To solve the stand debonding issue, two strengthening techniques by the separate use of carbon fiber-reinforced polymer (CFRP) and steel plate (SP) were proposed in this study. A detailed finite element analysis (FEA) model considering strand debonding, material deterioration, and retrofitting systems was developed and verified against relevant experimental data obtained by other researchers. The proposed FEA model agreed well with the experimental data. Based on the verified FEA model, 144 girder-deck systems were studied, considering the following variables: 1) debonding level, 2) span-to-depth ratio (L/d), 3) strengthening type, and 4) strengthening material thickness. A parametric study was conducted to investigate the effects of these parameters on the flexural response of girder-deck systems. Based on the data obtained from the FEA model, a detailed analytical model was developed and proposed to estimate the flexural strength of a debonding-damaged girder-deck system with strengthening systems. The analytical model was developed to calculate the ratio Ψ of the equivalent plastic length (Lp) to the neutral axis (c). Ψ was found to vary from 1.87 to 66.82. Multiple nonlinear regression analysis was performed using IBM SPSS Statistics 27.0.1 to formulate the equations. The equations of Ψ were formulated with a logarithmic function and an exponential function for the CFRP-strengthened and SP-strengthened specimens, respectively. The independent variable (X) is a linear function of three variables: debonding level (λ), span-to-depth ratio (L/d), and amount of strengthening material (A_f or A_SP). The analytical model was validated against the FEA results obtained by the authors. It was demonstrated that the analysis model could be employed to predict the flexural behaviors of debonding-damaged prestressed girder-deck systems. A simplified analytical model was developed and validated for predicting the ultimate moment capacity. The FEA, regular analytical, and simplified analytical models were demonstrated to be capable of predicting the ultimate moment capacity of strengthened girder-deck systems subjected to debonding damage with good accuracy. This simplified analytical model allows engineers to estimate the ultimate moment capacity.


Open Access

Available for download on Saturday, June 14, 2025