Advanced Materials Research Vols. 243-249

Abstract: This paper proposes a new calculating method for the reliability analysis of the time-varying structure，and applies the calculating method to optimize the design for the concrete structure . The RC compression member was taken as an example in the specific analysis in by the mean of resistance and structural reliability with time t. The results show that, this mode has a strong ability of analyzing adequately all kinds of random variant in procedure of structure failures.

Abstract: Hole-drilling strain-gage method for measuring working strains in concrete structures has been discussed by tests. Pre-loading strain has been used to simulate the working strain in concrete structure, and model beams have been sued for drilling measurement tests in the lab. Some key issues of this work have been studied, such as strain gages selected, waterproof, data continuous transmission out of hole, etc., and the strain release curves have been obtained. On the basis of the work, the effects of drilling depth (h), hole diameter (d), original strain and the environmental temperature have been analyzed, and general laws of working strains measurement described by strain released rates have been obtained. These results have been successfully applied in the existing bridge inspection, and referred for reinforcement design and construction.

Abstract: Earth-dwelling caves are a Chinese treasured historical cultural heritage. Nowadays, they are still widely used in some regions. They are primary ecological buildings with low energy consumption and nearly zero CO₂ discharge, which is in accordance with the belief of sustained development and the requirement of low-carbon housing. The construction of these caves are mostly based on the local craftsmen’s experiences and there are no calculation and drawing designing, but they have been lived in for a hundred or even several hundred years without collapse, which is worth exploring the structural secret within them. This paper has studied the reasonable and scientific values of the present existing earth-dwelling caves from the perspective of structural reliability. According to the material and structural characters of these caves, the paper used a response surface method to calculate the structural reliability. The result showed that the index of structural reliability for the earth-dwelling caves was higher than that for the same structures set by the present code. This explored the scientific secret of the existence of these caves and the research achievement will also provide an effective method for the analysis of the structural reliability of earth-dwelling caves.

Abstract: To provide guidance to engineering practice, the reliability of the vertical bearing capacity of single steel pipe pile is analyzed. The FOSM method, the FOSM method based on fuzzy stochastic and the FOSM method based on artificial neural network are used to calculate the reliability of steel pipe pile through MATLAB program. It is show that the FOSM method based on fuzzy stochastic and the FOSM method based on artificial neural network are more suitable for the reliability analysis.

Abstract: For analyzing effect of epistemic and aleatory uncertainties on failure probability of structure system involving uncertainties, two sensitivity indices, i.e. Correlation Coefficient and Correlation Ratio on the failure probability are defined, the universal method and approximate method for solving two indices are investigated and the corresponding precision and efficiency are discussed. By analyzing the two indices on the failure probability, the importance ranking of the uncertainty impacting on the failure probability can be quantified, on which the information for controlling the failure probability can be obtained effectively. After the detailing implementations for two sensitivity indices, several numerical and engineering samples are used to validate the precision and efficiency of two methods, and the law of the impact of the uncertainty parameters on the sensitivity result is obtained as well.

Abstract: In order to understand the strain fatigue crack growth rate of pressure vessel steel controlled by displacement or load, we did experiments on strain fatigue of 16MnR steel and describe the fatigue with the energy method. We have obtained delayed cycle curve of strain fatigue controlled by displacement or load and calculated the J-integral at crack tip. In order to compare strain fatigue crack growth rates of 16MnR steel on two conditions，we compute weighted means of the strain fatigue controlled by displacement or load. Comparing two kinds of fatigue growth rate, it is obvious that the crack growth rate of fatigue controlled by displacement is greater than that controlled by load. All experiments show that compress plastic energy is higher, the fatigue growth rate of 16MnR is lower.

Abstract: In this paper, a corrected method about the strength design of plain bolt group connection under combined load of transverse force and torque has been proposed based on the shortage of existing literatures, and its universal strength expression has also been derived. The results of examples show that the method is general application under all layout of plain bolt group, and is further rich in the design methods of bolt group. It can also provide favorable help for designers.

Abstract: Several representative design standards or manuals of overhead transmission lines home and abroad were selected, including Chinese<Technical regulation of design for tower and pole structures of overhead transmission line>DL/T5154-2002,American<Design of latticed steel transmission structures>ASCE10-97, European<Overhead electrical lines exceeding AC 45kV>EN50341-1etc., compared the reliability level of axial compression member of transmission tower in these standards, by calculating the comprehensive reliability coefficient under the strength limited state. Basically make the selected standards’ level of reliability degree clear, the specific data was got, and then gave some advice to UHV towers’ design about the setting of reliability level, which could not only provide a reference to understand the differentia of design standards home and abroad, but also to design the UHV transmission lines.

Abstract: Ultra high toughness cementitious composite (UHTCC) shows a unique characteristic of limit the crack width with multiple fine cracks whether it is subjected to tensile load or bending load. The failure pattern of UHTCC exhibits saturated multiple fine cracks, so the durability of structures will be improved markedly by utilizing UHTCC partly or entirely instead of concrete. In this study, considering the tensile strain capacity of UHTCC, a formula for calculating the critical rebar corrosion ratio when the UHTCC cover cracking due to rebar corrosion through the theory of plasticity and cylindrical cavity expansion theory. The effectiveness of UHTCC for restraining the cover cracking due to rebar corrosion has been proved by a calculated example. The influences on critical rebar corrosion when the UHTCC cover cracking due to rebar corrosion have been analyzed. The analytical results showed that UHTCC could effectively retard the cover expansive cracking due to corrosion of reinforcing bars, and prolong the service life of concrete structures subjected to the environment being at risk of corrosion.

Abstract: This paper studies several factors that affect the reliability of established structures .The theory of Data Mining is introduced into this paper as a new method to study the evaluation of established structures. New information is ultimately mined from “Data Sea” filed up in existed structures. According to the Chinese Structure Code and engineering experience, the factors affecting the reliability of structures are properly qualified as input parameters. This paper mainly researches with engineering structural examples on the theory of fuzzy cluster, which belong to the field of Data Mining. According to the analysis of the methods， it is found that the method put forward in this paper is practicable, reliable and effective.