Applied Mechanics and Materials Vols. 204-208

Abstract: Based on analysis of the Corrosion prestressed concrete beam with finite element model, the paper presents the mechanical performance of concrete beams in different corrosion rates. When the corrosion rate is less than 5%, the strand corrosion has little impact on the load capacity. With the increase of the corrosion rate more than 5%, what damage happened to Beam is little steel damage and brittle damage even without apparent warning and at the same time the Corrosion of steel strand will cause the decrease of the ultimate load capacity with the deterioration of ductility.

Abstract: An efficient reliability analysis method has been proposed in the paper, which based on stochastic response surface method. The key advantage of the stochastic response surface method is that the collocation points are selected for minimizing the mean square error, and from high probability regions, thus leading to fewer function evaluations for high accuracy. Compared with Monte Carlo method, the proposed technique can be more efficiency while achieve comparative accuracy.

Abstract: In the interest of an understanding to the imperfection stability behavior, a model of single layer spherical lattice shell was designed. The size and the pattern of initial imperfections were entirely measured. Automatic harmony loading control system and data acquisition system was used. The experiment plan, method and results have provided reference significance for the study on the stability of spatial lattice shell. The experimental results and the results of measured imperfections method were compared and analysed in detail. It is verified that measured imperfections method can accurately take into account of the effect of initial imperfections and it can be used for the supplementary checking computations of some important finished structures.

Abstract: The chemical compositions and the microstructures of reinforcing steel bars obtained from three different collapsed building sites were studied. Optical emission spectrometer was used to carry out the chemical analysis, while the microstructure was examined using an optical microscopy. The carbon contents of the steel bars were found to be higher than BS4449 and ASTM706 standards, but they are in close range with the Nst-65-Mn standard. The manganese contents of the steel bars are lower, while the sulphur and phosphorus contents are quite higher than the BS4449, ASTM706 and Nst-65-Mn standards. The hardness values of the investigated bars are higher than recommended BS4449 standard but lower than Nst-65-Mn standard. Brittle globules of Fe3P and FeS were observed within the structure possibly due to higher contents of deleterious sulphur and phosphorus. The results suggest that the investigated reinforcing bars are brittle and thus contributing significantly to the collapse of the building structures.

Abstract: According to engineering analysis on the performance and the causes of constructive faults of mortar masonry retaining wall , such as drain hole losing effectiveness, settlement joints out of plumb, mortar of pointing falling off and surface’s unevenness, and their prevention measures are summarized.

Abstract: Cable-arch structure is a combined structure, which utilizes flexibility of cable and rigidity of arch. Cable-arch structure has been widely used in bridge engineering. In this work, we proposed a novel mechanical model of cable-arch structure. The out-of-plane buckling and in-plane buckling were studied using the energy method. The formula of critical loads of both the first order out-of-plane buckling and in-plane buckling were derived using Rayleigh-Ritz method. An example is ultimately investigated numerically. The results indicate that the cable can improve considerably the out-of-plane and in-plane stability of arch. Therefore, the research about the stability of cable-arch structure are both valuable not only in theoretical research but also in design of engineering structure.

Abstract: Seven concrete beams were constructed with normal reinforcement bars. Grooves were opened on the concrete cover of the tensile region in the concrete beams using different combinations of carbon fiber reinforced plastic (CFRP) and pre-stressed helical rib bar (HRB), CFRP and HRB pre-stressed at different levels were inserted into the grooves and filled with resin. Flexural experimental results indicated that the limit bearing capacity, rigidity, and crack resistance of the beams were strengthened significantly with near-surface mounted two pre-stressed HRB and one CFRP (BF1P2) bar, or near-surface mounted one pre-stressed HRB and two CFRP (BF2P1) bars, in which HRB was pre-stressed at 30%, 45%, and 60% of its limit strength, respectively. Compared with an un-strengthened beam, the crack loads of the BF1P2 beams increased by 86.70% and 133.33%, the yield loads by 32.25% and 72.04%, and the limit bearing capacities by 72.73% and 90%. The crack loads of the BF2P1 beams increased by 50% and 133.33%, the yield loads by 50.54% and 136.56%, and the limit bearing capacities by 72.20% and 173.60%. The BF1P2 beams had better reinforcing results compared to those of the BF2P1 beams. The beam strengthened with HRB pre-stressed at 45% of its limit strength was the best concrete beam.

Abstract: Abstract. By introducing the Heaviside step function into assumed displacement components and using the Rayleigh-Ritz method for minimizing the total potential energy, a set of dynamic governing equations for the delaminated beam is derived. Then, the dynamic governing equations are written as the Mathieu-type equations to describe the parametric vibrating behavior of the beam, and these equations are solved by employing the Bolotin’s method. Numerical results in dynamic stability of laminated beam with delamination are presented, and the effects of static loading, delamination length and material property on the principal dynamic instability region of the laminated beam are discussed. Present results are compared with available data.

Abstract: Numerical simulation method is adopted to analysis the stability of tailings dam under the fluid-solid coupled interaction. Using the full-coupled analysis function, stress field 、seepage field and their coupled model are studied in this paper. Finally, the critical sliding surface of the tailings dam is searched. Results show that the safety factor after coupling is smaller than before. It illustrates that the fluid-solid coupling analysis has an important practical significance for the stability analysis of tailings dam.

Abstract: This paper analyzed the cracking behavior of carbon fiber reinforced concrete beam under static load using the finite element numerical analysis. By the way of finite element numerical simulation and the method of increasing the load gradually to analyze the carbon fiber content influence on the beam cracking, crack developing, beam deflection and beam average crack spacing. By comparing with the simulation result of common reinforced concrete beam test piece, it turned out that the carbon fiber reinforced concrete beam has a good cracking and deformation behavior under the same ratio of reinforcement. Under the same load, both the carbon fiber reinforced concrete beam and the common reinforced concrete beam have a small deformation, but the carbon fiber reinforced concrete beam showed a better resistance to deformation as the load increasing, its deflection increasing extent showed an obvious decrease compared with that of the common reinforced concrete beams. Its crack width can be revised by the common reinforced concrete beam rules.