Advanced Materials Research Vols. 243-249

Abstract: The paper presents the results of an experimental study on fatigue performance of corroded reinforced concrete (RC) beams repaired with carbon fiber reinforced polymer (CFRP) sheets. Five beams were constructed. One specimen was strengthened and not corroded; another four specimens were corroded and was strengthened with CFRP sheets. Five specimens were tested in fatigue. The results showed that steel bars corrosion reduced the fatigue life significantly while the CFRP strengthening enhanced the fatigue performance significantly. The effects of reinforcement corrosion on fatigue behavior of the strengthening beam can be attributed to a combination of four factors, including deteriorated bond behavior between reinforcement bras and surrounding concrete, loss of effective cross-section area of reinforcement, the stress concentration on steel bars, and degradation of mechanical properties of steel bars.

Abstract: Using utilities equipment to make the reinforced concrete girder to generate a kind of reverse-arch radian, then paste CFRP on the under-part of the girder, after the CFRP was maintained, unload, at this time, the CFRP is working together with the primary reinforced concrete girder. Using analysis software ANSYS to simulate this process, comparing with the RC beam strengthened with carbon-fiber directed, a conclusion was got that is the deflection of a RC beam strengthened with carbon-fiber by reverse-arch method is much smaller and the CFRP to bear much loads than the ordinary method. The conclusion can be a reference to the similar projects.

Abstract: On the basis of the destructive characteristics of aging RC beam bridges, experiments are conducted to examine and compare the effect on RC beams strengthened with FRP surface adhesion (EB-FRP) and FRP-bolt hybrid boding (HB-FRP). In particular, the influence of pre-cracking level on RC beams strengthened with the hybrid bonding of FRP is assessed. The experiment results show that the hybrid bonding of FRP is a more reliable strengthening technique which can improve the Flexural capacity of beams. The new bolt-fastening technique does not rely on bearing to transmit the interfacial shear, but increases the interfacial bond by resisting the separation of the FRP laminate from the concrete substrate by the bolt pretension instead. This study contributes to direct the design and the construction of HB-FRP.

Abstract: This paper introduced a project of reinforced concrete chimney with a height of 90 meters, which does not stop construction at nearly 200 degree Celsius, increased the height of the chimney with 10 meters. Reasonable structural measures were promoted to ensure the normal pouring of concrete chimneys. Compared with the normal condition, this measure is economical, low investment, feasible, etc. It provides far-reaching significance that increasing the height of the reinforced concrete chimney at the high temperature state.

Abstract: Jiangsong villa is the famous ancient architecture in Longmen scenic spot. The appearance and structural members of villa are damaged seriously because of long-term natural action. Load bearing capacity of the structure reduces largely and should be repaired immediately for the cultural relic protection and tourism development. According to the surrounding requirement of scenic spot, the performance of damaged members is detected and reasonable reinforcement methods are put forward in this paper.

Abstract: The research program is aimed at investigating the effectiveness of application of good ductile hybrid fiber reinforced polymer (FRP) to upgrade corroded RC beams. A total of 5 RC beams are tested under flexural load, the results show that compared with the un-strengthened corroded RC beam, the crack, yield, maximum and ultimate load of corroded RC beam strengthened with hybrid FRP sheets is increased by 14%, 35%, 102% and 109% respectively, and the displacement ductility factor is only decreased by 11%, which indicate that the hybrid FRP sheets can improve significantly the flexural performance of corroded RC beam.

Abstract: A high filled subgrade of a highway slipped on the left of the line. According to conventional calculations (limit equilibrium method) ,we can know that the safety factor K = 1.55 and the probability of reliability index β = 3.1, failure probability P_f = 0.001. Through the introduction of interval analysis theory, non-probabilistic reliability calculation model is established, and the non-probabilistic reliability index is η = 0.7. Showing that the non-probabilistic reliability theory in the absence of adequate data distribution of information and possible subjective assumptions can also obtain more accurate results.

Abstract: Probability distribution law of corrosion initiation time of steel in concrete under chloride environment is discussed. Based on the Fick’s second law, by Monte Carlo, frequency distribution, distribution type and probability density is analyzed. The statistic parameters of the factors influencing the probability distribution of corrosion initiation time are studied and the expression for sensitivity analysis of corrosion initiation time is deduced. By sensitivity analysis can know, corrosion initiation time is found to be more sensitive to cover than the diffusion coefficient, and more sensitive to surface chloride concentration than the critical chloride level. The analysis of the paper perfects the methods of predicting the corrosion initiation time.

Abstract: Fuzzy techniques and AHP approach have been widely used during the last decade. However, few papers have attempted to use the AHP approach that incorporates fuzzy techniques to evaluate the damage of framework. This paper, therefore, aims to set up a hierarchy structure of the damage and then develop a fuzzy analysis of framework for the damage evaluation of framework. In the process of damage evaluation, setting up the hierarchy structure, determining the weight vector by the AHP, setting up the fuzzy evaluation matrix and developing fuzzy AHP evaluation are detailed according to framework. Finally, 5-story framework is used to execute the proposed fuzzy AHP model. It is concluded that the results is effective and accurate.

Abstract: Various potential sliding paths and different failure modes should be considered in the stability of gravity dam against deep sliding when there are several faults. The safety factor of every fault is calculated with nonlinear finite element method, and the most possible sliding path is obtained by strength reduction method. The results indicate that the strength reduction factor is larger than the safety factors of all the faults. Based on the weighted regression response surface method, the reliability indices of the faults are computed and are compared with the safety factors, which shows there’s not an entire equity relationship between the reliability index and safety factor. Each failure mode of sliding path is a parallel system of several faults, and the final failure mode is the serial system composed of all sliding paths. The reliability of every sliding path and the final system are analyzed by means of the gradual equivalent linear method, and the results are consistent with the strength reduction factor. It’s recommended the reliability analysis be applied to the safety evaluation of deep sliding stability of gravity dams to make up the shortcomings of the safety factor method.