In order to help engineers to better learn from accidents of reinforced concrete structures, accident identification and processing method, this article introduced the ideas of CBR to the accident case retrieval methods of reinforced concrete structures. At the same time, the fuzzy retrieval and knowledge index model of reinforced concrete structure accidents are presented. According to the approximate extent of construction conditions, the approximation of construction are determined, and similar cases with the current engineering cases then retrieved through the case of reinforced concrete structures, which the designer or construction workers can learn from.

This paper presences the influence of coarse aggregate-space coefficient on the rheological properties of self-compacting concrete (SCC). The results indicate that coarse aggregate-space coefficient has significant influence on slump flow and V-funnel flow time of SCC, when the maximum aggregate particle size is 16mm and the volume ratio of sand and motor is 0.43, meanwhile water binder ratio is 0.38. The higher the coarse aggregate-space coefficient, the lager the slump flow, the shorter the V-funnel flow time. The range of coarse aggregate-space coefficient of SCC is suitable for 1.31~1.58 under the condition of the paper. The suitable range can guarantee excellent rheological properties and stability of SCC mixture. There is little effect of coarse aggregate-space coefficient on compressive strength in this paper tests.

Chloride ion penetrability of concrete under and after compressive stress was tested in the paper. Four stress level (the ratio of the pressure load and ultimate load) was set: 20%, 40%, 60% and 80%. Chloride ion penetrability of concrete was tested using a rapid test method of electric flux. The results indicated that the electric flux of concrete under compressive stress was influenced by stress level, and the electric flux of concrete was first decreased and then upward with stress level increasing. The electric flux of concrete of different strength grade was sensitivity to compressive stress differently, and the lower the strength grade of concrete, the high sensitivity to compressive stress. The electric flux of concrete after compressive stress was related with crack recovery, and there was a significant effect of only more than 60% stress level on the electric flux of concrete. The evaluation of chloride ion penetrability of concrete structure should take into account the loads.

A new method taking the second derivative of low-level axial vibration modal shape as damage index is presented on the basis of theoretical derivation axial vibration differential equation and analytical solution of three kinds of support form. The index is very sensitive to damage location and damage degree. In addition, the effect of point number is analyzed and results showed that with a few points can still calibration damage well.

The value of sensitive factors in structural reliability analysis greatly affects reliability calculation results. These factors must be accurately determined and studied to improve the accuracy of calculated results. Based on the analysis of existing sensitivity calculation methods, a new practical sensitive factor analysis method was put forward to analyzing sensitive factors in structural strength reliability calculations. The dimensionless sensitive indexes of structural reliability were defined in the new method to compare the influence degree of random parameters to reliability. And the method was applied to analyze sensitivity under the two conditions of the structural resistance decreasing and not changing with time. Random variables, defined by their probability distribution and corresponding distribution parameters, were used to describe uncertainties in the reliability calculation. Different forced state RC columns were taken as examples to analyze the structural sensitivity, and sensitive factors affecting the columns’ structural reliability were obtained. The results show that the reliability of time-varying structure has descended to some extent compared with that without time-varying structure, and the effect from the random parameters to reliability index. The example and theory demonstrate the feasibility and rationality of the new method. This article has certain reference value to the structural design, construction and detection.