Applied Mechanics and Materials Vol. 188

Abstract: “Intelligent Construction” is an innovative idea adapted to a new era of development for the construction industry. In promoting the development of “Intelligent Construction” concept, it can make various stages of the design; the construction and implementation of a project more effective in conserving resources, saving costs, reducing pollution and improving the efficiency of the desired target. BIM is an integrated expression of the construction projects information and model. The effective use of BIM technology can improve the efficiency of the projects construction, while saving cost thus making “Intelligent Construction” necessary. This paper is to propose a strategy for BIM Intelligent Construction, based on a through analysis of the concept of Intelligent Construction and the relationship described between BIM and Intelligent.

Abstract: The aim of this paper is determination of embedment strength of cement-splinter boards in dowel dual-shear joints on the base of destructive laboratory measurements of these joints with selected diameters. Reliance of embedment strength on dowel diameter is determined.

Abstract: Use of a sliding joint is an effective method to decrease the stress in foundation structure where there is a horizontal deformation of subsoil (areas afflicted with underground mining) or horizontal deformation of a foundation structure (pre-stressed foundations, creep, shrinkage, temperature deformation). A convenient material for a sliding joint is a bitumen asphalt belt. Experiments for different types of bitumen belts were undertaken at the Faculty of Civil Engineering - VSB Technical University of Ostrava in 2008. Since 2011 an extension of the 2008 experiments has been in progress and the shear resistance of a slide joint is being tested as a function of temperature in a temperature controlled room. In this paper experimental results of temperature dependant shear resistance are presented. The result of the experiments should be the sliding joint shear resistance as a function of deformation velocity and temperature. This relationship is used for numerical analysis of stress/strain relation between foundation structure and subsoil.

Abstract: Although real-time tracking and feedback were carried out for the dam concrete construction process, there was still certain blindness in the construction units. The temperature double-control index, which is the allowable temperature and temperature gradient under typical age before concrete block reaching its maximum temperature, was proposed in this paper on the basis of the analysis of measured temperature process curves of concrete blocks. The probabilistic method was applied to draft the temperature double-control index of different sections and periods based on the measured temperature process curve of the poured block of a constructing extra-high arch dam in southwest China. Furthermore, the prediction model was also provided and applied in the dynamic feedback of new pouring block. It is demonstrated by the practice that the prediction model proposed in this paper has better pertinence and maneuverability for the construction units to control the maximum temperature of concrete block, i.e. the maximum temperature in high temperature season and in low temperature season are both controllable.

Abstract: Combined with the equilibrium condition, the formula of vertical average sediment concentration has been derived from the vertical two-dimensional suspended sediment diffusion equation. Based on analyzing and comparing two hydrodynamic formulas, a new formula of sediment carrying capacity has been deduced. Some river and inshore sediment data has been collected to validate the formula and find that the new formula has higher accuracy and applicability comparing with the two hydrodynamic formulas, it shows that the new formula has a high application value.

Abstract: Most of the cracks on concrete dam are external ones, while external heat preservation is an important measure to prevent cracking. In order to obtain the actual thermal parameters, according to thermal conduction theory and the temperature distribution conditions of optical fiber on concrete surface, the surface temperature distribution of concrete pouring deck was real-time monitored by setting optical fiber in different depths; then the surface heat flux of mass concrete was calculated, thereby the equivalent surface heat transfer coefficient, which varied as time goes, was inversed. It is indicated that the inversion process is relatively simple and reliable, and the heat transfer coefficient obtained can well reflect the real performance of the insulation materials. Meanwhile, it is also indicated that the heat transfer coefficient of equivalent surface varies as time goes, which can contribute to back analysis calculation and actual engineering practice.

Abstract: A research on numerical modeling of arch dam with contraction joints under static and seismic conditions is performed in this study. Discussions on the use of the adaptive finite element method with consideration of the “equivalent stress” and simulating technique for the contact between dam segments are presented. A case study of stress analysis for the Namchien hydropower arch dam in Vietnam is given. The results showed that the numerical model established in this paper is effective to simulate complex physical models. The stability analysis is easily performed by using the self-adapting technique with consideration of equivalent stress, and the contraction joints between dam segments can be successfully simulated by assigning zero-thickness contact elements to control complex contact behaviors, such as slip, opening or closing of the contact surfaces. The results of this study will be a useful reference for the assessment of the dam safety in the future.

Abstract: Averaging pitot tube has been applied in practice more often in these years. This paper set up the two-dimensional model of the bullet-shaped averaging pitot tube, numerical simulation based on CFD was used to investigate the changes of flow coefficient along with the Reynolds number. The geometric size of the section was changed to investigate how it influences the flow coefficient and differential pressure. To guarantee the accuracy of the simulation, the grid and the simulation model were investigated too.

Abstract: In order to realize defect imaging for guided waves inspection in a pipe, a time reversal method based on baseline subtraction method was introduced. In this method, baseline signals were prepared by detection on undamaged pipe. After that residual signals were obtained by executing subtraction between inspection signals and baseline signals. At last, without using the rectangular window for signal interception, time reversals signals are produced by time reversing the whole residual signals. Experiment and numerical simulation results show that this method simplifies the existing time reversal defect imaging method for guided wave inspection in pipes. Especially, a relatively whole defect’s passive wave field captured by this method will help us to achieve better imaging effect.

Abstract: In engine compartment, it is difficult to eliminate the effect of interfering signals on vehicle AFM signal by the traditional processing method. According to the characteristic of AFM signal, this paper decomposed the noise signal for 4 layers by selecting Daubechies (db5) wavelet in Matlab based on wavelet theory. After decomposing, and then employed the soft-threshold de-noising method to eliminate noise. At last this paper used the inverse wavelet transform to reconstruct signals for signal de-noising and rebuilding. The test results show that this method can eliminate the noises of AFM signal effectively.