Case Studies in Construction Materials最新文献

The shear characteristics of the concrete-rock interface play a crucial role in the stability of engineering structures in geotechnical construction. This study utilized a combination of three-dimensional scanning and sculpting techniques to create fiber-reinforced shotcrete-granite combination specimens. Specimens with varying interface roughness were tested in direct shear under different normal stress conditions. A method for analyzing the shear failure characteristics of granite interfaces using the XTOM industrial optical surface scanning system is proposed. Furthermore, an enhanced formula for estimating the peak shear strength of the interface in fiber-reinforced concrete-rock composite specimens is introduced. The research findings suggest the following: (1) The shear strength of the fiber shotcrete-granite interface is significantly increased by normal stress. Specifically, under joint roughness coefficient (JRC) 2.0 conditions, the shear strength at a normal stress of 2.0 MPa is 185.89 % higher than at 0.5 MPa. (2) A method for analyzing the damage characteristics of rough interfaces using surface scanning technology is introduced. Utilizing surface scanning technology, the rough surface is reconstructed both before and after damage, allowing for the extraction of a two-dimensional roughness curve that effectively captures the influence of normal stress and roughness on interface shear failure characteristics. (3) Based on the observed macroscopic and microscopic damage characteristics, as well as the scanning electron microscope (SEM) morphology of the interface after shearing, it is evident that shearing damage predominantly occurs on the side of the fiber-reinforced concrete. Furthermore, it was found that the degree of damage on the concrete side increases with higher roughness and normal stress levels, while the interface shear strength is enhanced by the presence of alkali-resistant glass fiber (ARGF). (4) The calculation formula of concrete-rock interface shear strength was improved, and its accuracy was verified through experiments. The research findings can serve as a data foundation and theoretical support for studying the shear characteristics of fiber-reinforced concrete-rock interfaces and geotechnical engineering construction.

Prestressed bonded strengthening for structures employing iron-based shape memory alloy (Fe-SMA) has been proven promising. Analyzing adhesively bonded joints necessitates a thorough understanding of the bond-slip behavior. However, when examining the bond-slip behavior of Fe-SMA-to-steel joints comprising nonlinear adhesives, the “forward” and “backward” post-processing methods, representing the current state-of-the-art, produce a trilinear and a trapezoidal bond-slip pattern, respectively, which is inconsistent. To address this inconsistency, the current study investigates the bond behavior of Fe-SMA-to-steel joints, with a particular focus on the bond-slip behavior. Two finite element (FE) joints, one featuring a linear adhesive and the other comprising a nonlinear adhesive, are modeled and compared against physical tests from literature. The “forward” and “backward” processing methods are used to analyze the bond behavior of the two FE joints. Eventually, the aforementioned inconsistency is resolved; a triangular and a trapezoidal bond-slip pattern are characterized for Fe-SMA-to-steel lap-shear joints with linear and nonlinear adhesives, respectively. The trilinear bond-slip behavior is concluded as a result of error accumulation and propagation during the “forward” processing. A hybrid post-processing method, which takes the advantages of both the “forward” and “backward” processing methods, is further proposed for inferring the full-range behavior; the resulting experimental behaviors closely align with simulations using a trapezoidal bond-slip model as input. A comparison against carbon fiber reinforced polymer (CFRP) lap-shear joints demonstrates similar bond-slip characteristics between Fe-SMA and CFRP lap-shear joints.