Applied Mechanics and Materials Vols. 351-352

Abstract: This paper analysis and reviews the calculation and the predicting model of concrete carbonation depth, also discusses the influence factors of concrete carbonization and the applicability of the predicting model. In order to reduce or avoid the effect of complex factors such as material composition, humidity and temperature on the calculation of the carbonation depth and the prediction results, the predicting model of concrete carbonation depth based on the time-series changes is investigated. In this model, Box-Jenkins time series analysis is utilized to establish the regression model-AR model, which reflect the concrete carbonation depth changes over time. The research and analysis shows that the model has characteristics of simple and high precision, and with the measured data increased and updated, the prediction result is getting better and better. Using this method to evaluate the life of concrete structures which under the affection of carbonation, only need to test the carbonation depth of concrete, and the other parameters is not need consider.

Abstract: The connectivity reliability of a network states the probability that the traffic can reach the destination from the origin. This paper is dedicated to find a reasonable and fast method to calculate connectivity reliability between any two nodes of a network. Monte Carlo simulation and ORDER algorithm are used and compared in getting the network connectivity reliability. The results show that ORDER algorithm can give more accurate bounds of connectivity reliability for network with high reliable components, while the computation time of Monte Carlo simulation is shorter than ORDER algorithm. Both approaches are applied to the network in the Bridge Management System in the Autonomous Province of Trento.

Abstract: With the development of China's science and technology and economic construction, the structural design of the reliability theory, security and reliability level of economic balance facing new development. This paper analyzes the impact factors of reliability in structural design, in order to do some preliminary exploration for the specification revision and adjustment of reliability design.

Abstract: The aim of this paper is demonstration of usage possibility of fully probabilistic methods for design and assess of timber structures elements due their expression of material properties with bounded histograms because timber in terms of one strength class shows broad range of strength properties.

Abstract: Through carrying capacity test of CFRP strengthened test beam and unstrengthened comparison beam under corrosion of chlorine ion, thispaper analyzes the shear resistance and durability of CFRP repaired and strengthened concrete beam. Crack generation, deflection, electrochemical index and deformation of reinforced concrete beam under service are comparedand analyzed. It is indicated that CFRP can play a favorable screening role and can effectively prevent crack development. There is no shear failure after load is applied. So CFRP can obviously improve the shear bearing capacity and durability of reinforced concrete beam. Besides, different strengthening methods have relatively obvious influence of its durability.

Abstract: Fully-welded ball valve has been applied in large oil and gas pipelines, and its quality is directly related to the safety of the transportation of national energy. The wall thickness of 48900lb ball valve is greater than theoretical design thickness. In this article, FEM software was used to design ultimate bearing pressure by means of linear stress analysis method. By applying different inner pressure load, the stress distribution of the ball valve was studied. Stress verification lines were draw at stress maximum location and each stress item were checked under corresponding safe value. Optical design obtained maximum inner pressure can provide theoretical support for practical engineering application.

Abstract: On the basis of the theory of structure reliability, the optimization algorithm according to the geometric significance of the reliability index and the checking point method are studied to calculate the reliability of the bracing structure for foundation pit. Combined with a soil nailed wall engineering example, the primary data calculation table is established to solve the non-linear programming problem adopting the embedded planning solving method of Excel software and the results indicate that the reliability index and the coordinates of the checking point are same nearly using the checking point method and Excel planning solving method, but the latter is more efficient and convenient than the former, it means that it is feasible to calculate the reliability index of the bracing structure for foundation pit by Excel optimization algorithm.