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Steel corrosion in reinforced concrete (RC) structures leads to change of steel mechanical properties, longiludinal cracking in the concrete cover, and other related effects that weaken the serviceability and load capacity of the composites. It is therefore extremely important to have methods targeted to the evaluation of the structural damage reduced by corrosion for estimating the residual load capacity of a structure, and then for inspection procedures and strengthening the maintenance interventions. This paper presents a simplified methodology capable of providing estimates of the residual life of corroded RC beams. The proposed method uses damaged material properties, and accounts for the length of partial corrosion and the amount of corrosion, concrete loss and change of bond strength within this specified length. A comparison of the model predictions with the experimental results published in the literature shows the validity of the model. It is also concluded that the ultimate flexural moment of corroded RC beam will not significantly influenced by the partially corroded or unbonded length and the bond characteristics over this partial length as long as the tensile steel of the beam can reach its yield strength, in addition, although complete loss of bond over the partial length is assumed to asses the residual strength of corrosion-damaged RC beam, neglecting the influence of bond strength within the corroded length may lead to underestimate the ultimate flexural capacity of the damaged beam, especially when the corrosion level of tensile steel of the RC beam is not very high. DOI: 10.1061/(ASCE)CF.1943-5509.0000083 CE Database subject headings: Reinforced concrete: Concrete beams corrosion: Load bearing capacity; Residual strength. Author keywords: Partial length: Corrosion: Bond: Bearing capacity: Residual strength.

The localization of damage for bridges to ensure their safety is investigated in this paper. Equivalent element concept is introduced into this study at the beginning. Support reaction data of each bearing under truck load are found to be able to lend themselves to indicate damage. A novel index termed as symmetrical support reaction difference index (SSRDI) is then developed. The reverse mapping between the local flexural stiffness change induced by damage and the SSRDI is generated. The proposed method based on SSRDI can be sensitive to tiny damages, and comparatively simple measurements are required during the application procedure. Another significant attraction of this method is that it can work in the presence of random uncertainties and actual support condition, which means it is suitable for real-world bridges. The effectiveness of the proposed method is demonstrated by numerical simulations performed on two kinds of bridges with reasonable damage severities. Its comparative advantage over the previous frequency method is also investigated. [ABSTRACT FROM AUTHOR]

This study presents a new idea of using only mid-span displacement measurement for damage detection of simply supported beams. Equivalent element concept is introduced at the beginning. In order to relate the damage detectability by means of mid-span displacement measurement with the damage-caused local stiffness change, a novel index termed as symmetrical mid-span displacement difference index (SMDDI) is proposed. The proposed method based on SMDDI is sensitive to tiny damage and comparatively small quantities of measurements are required during the application process. Another significant attraction of this method is putting aside the knowledge a-priori of the intact state. An example using simulated data has been conducted to examine the suitability of this method and assess its comparative advantages over the previous modal method. [ABSTRACT FROM AUTHOR]

The unified equations and graphs on the general failure expression were presented through the study of reinforced concrete elements with annular section. The stress equations are established, then the stresses are expressed in the term of outer forces. Finally, the unified equations and graphs can be got out by inputting the stress expression into the stress equations. Using the result of plasticity mechanics, fracture mechanics and materials mechanics, the general failure expression on reinforced concrete members was put forward. [ABSTRACT FROM AUTHOR]

A method based on component stiffness was provided to calculate the importance indices of structural components and also the relationship between importance indices and structural redundancy was given, which is proved by the theory of minimum of potential energy. Two practical examples are given for illustrating. It is shown that the method can explore the weak parts in a structure and offer necessary theoretical foundation for the structural primary design and maintenance. [ABSTRACT FROM AUTHOR]

A new model of pounding between adjacent structures was brought forward. By establishing the pounding-imposed velocity restraint condition, the pounding analysis is carried out by solving the equations of motion in impulse. The impact force is incorporated implicitly into the governing equations in terms of constraint impulse, which need not be obtained in advance. Moreover, it can be traced out by simple element handling if necessary. In the end, pounding analysis between two frames was performed to show the efficiency of the presented model. [ABSTRACT FROM AUTHOR]

According to the characteristic of structural resistance degradation, a multi-layer Bayes resistance model was established to take into account the epistemic uncertainties in model selection and model parameters. The random variables in model selection and model parameters can be updated with the introduction of new information, including direct inspection, indirect inspection and proof loading. With a case study the updating procedure was illustrated. It shows that the multi-layer Bayes model can efficiently regard the epistemic uncertainties, and the information updating can combine prior information and specific information to reduce knowledge-based epistemic uncertainties, thus makes reliability analysis more accurate. [ABSTRACT FROM AUTHOR]