Search

On the premise of following the concept of culture heritage conservation, the technique of wooden bolt anchorage plays an important role in the conservation of rammed earthen sites. The existing researches on single anchoring cannot reflect the mechanical behaviors of an anchor group. To solve this problem, this study proposes a load-transfer method achieved by a universal joint combined with a load-bearing platform. Three rammed earth models were tested by continuous loading, with embedded length, bolt interval, and margin as variables. The failure mode, ultimate pulling resistance, load–displacement relationship, and interfacial strain distribution of the anchorage system were analyzed. Results show that the two bolts present sequential failure. Meanwhile, the failure of wooden bolts is not in a single mode; instead both interfacial debonding and soil-bearing capacity loss were observed in soil at the same time. The bolts are mostly in plastic-slipping state under working conditions. The strain is unevenly distributed at the bolt—grout interface and highest near the loading side. Spacing effect and marginal effect are important factors affecting the pulling resistance of two bolts, and their importance is higher than the quality of a single bolt. In addition, numerical simulations on behaviors of two wooden bolts, considering the interval distance, margin distance, embedment length, and layered property of rammed earth, were established by "interface" element, which supplemented and expanded the model test results. Results of this paper could provide deeper understanding of the macroscopic performance and internal mechanism of a two-bolts group. [ABSTRACT FROM AUTHOR]

To analyze the tensile properties for the single-strap butt joint of a carbon fiber reinforced composite, a finite element model was established using no. 22 and no. 185 materials based on LS-DYNA with the test data and the theoretical solutions reported by Li et al. Then, the tensile properties influenced by three factors were analyzed, i.e., the connection strength, the failure mode of the composite, and the adhesive stress. The results show that the adhesive interface of 0° stacking can greatly improve the tensile strength and reduce the composite matrix tensile damage. With the increase of the adhesive thickness, the connection strength decreases first and then increases. As for the overlap length, its increase is conductive to the tensile strength but detrimental to the lightweight design. Therefore, these factors should be taken into consideration when designing the joint. [ABSTRACT FROM AUTHOR]

To study the compressive mechanical properties of a new type of brazed aluminum honeycomb plate (BAHP), tensile tests on single- and brazed-cell walls as well as compression tests in the out-of-plane, in-plane longitudinal, and transverse directions were conducted. Compared to the material properties of a traditional glued aluminum honeycomb plate (GAHP), those of the single- and brazed-cell walls of the BAHP are entirely different. Therefore, their characteristics should be considered separately when performing theoretical and simulation analysis. Under out-of-plane compression, the core of the BAHP did not debond, owing to its higher strength than that of the GAHP. In comparison, under in-plane compression in the longitudinal and transverse directions, the load–displacement characteristics, ultimate load, and failure modes also differed, and there was no large-scale cracking. Considering the characteristics of the BAHP, a strength prediction method was proposed. The simulation results demonstrated that the model built based on the new method was highly consistent with the experimental results. Defects with uneven height and debonding will cause the overall instability, and the degree of defects will influence the strength and instability displacement, which have little impact on the elastic stage. Moreover, the model considering defects is closer to the test results. [ABSTRACT FROM AUTHOR]

The purpose of this research is to study the influence of aspect ratio and end conditions on the strength and failure mode of remolded soil samples in unconfined compressive strength tests. The digital image correlation method is used in this research to obtain the evolution process of the horizontal displacement field in remolded soil samples and analyze the deformation and failure characteristics in various sample sizes. Two-dimensional discrete element models of the soil samples are established to simulate the impact of different end-frictional conditions on stress-strain processes of samples. Results show that, with the growth of aspect ratios, the failure of samples transforms from tensile mode to shear mode, and the defects in the middle of samples become more obvious. Characteristic values of earthen sites' soil, such as peak strain, elastic modulus, and residual stress, change with various aspect ratios. The simulation results are in accordance with typical experiments, thus verifying the rationality of established discrete element models. By comparing the particle displacement directions and the respective proportions, the constraint caused by loading plate on samples is proved to be one of the reasons for the size effect. When the aspect ratio is higher than 1.0, the size effect disappears in end-frictionless samples. The research has practical significance to deepen understanding of the mechanism for unconfined compressive strength of site soil samples and provides scientific references for protection and reinforcement of earthen sites. [ABSTRACT FROM AUTHOR]