In rock masses, internal defects such as joints, faults, and fractures are pivotal in determining mechanical behavior and structural integrity. This investigation, employing the discrete element numerical simulation technology of GDEM, examines the mechanical attributes of single-fractured sandstone under standard triaxial compression. The study focuses on how fracture inclination angle and confining pressure affect crack propagation within the rock. It is observed that an increase in both fracture inclination angle and confining pressure correlates with a reduction in the tensile stress growth rate near the fracture, indicative of inhibited crack propagation. A notable transition in the failure mode of the sandstone samples is identified, shifting from tensile-shear to predominantly shear failure. This shift is more pronounced under varying confining pressures: Low confining pressure conditions show a prevalence of tensile-shear damage units in proximity to the fracture, while high confining pressure leads to a dominance of shear damage units. These findings contribute to a deeper understanding of fracture mechanics in rock materials and have significant implications for geological and engineering applications where rock stability is critical.
Glued laminated timber (glulam), a composite material fabricated by bonding multiple wood layers, is engineered to support specific loads, offering reduced product variability and diminished sensitivity to inherent wood characteristics, such as knots. This technology facilitates a wide array of architectural designs, rendering it a popular choice for load-bearing elements across diverse construction projects, including residential structures, storage facilities, and pedestrian overpasses. Over time, exposure to various environmental conditions leads to the degradation of these structural components, necessitating periodic reinforcement to maintain their strength properties. Recent advancements have seen the adoption of fiber-reinforced polymer (FRP) for the reinforcement of columns and beams, a departure from traditional strengthening methods. This study focuses on the connection of column-beam joints using an array of steel fasteners, subsequently reinforced with FRP. Rotational tests were conducted on these fabricated connections, followed by a comprehensive analysis using the finite element method (FEM). Results indicate that connections reinforced with FRP exhibit a significant enhancement in load-carrying capacity, energy dissipation, and stiffness compared to their unreinforced counterparts. Specifically, the load-carrying capacity showed an increase of 25-39%, energy dissipation capacity augmented by 64-69%, and stiffness values rose by 2-7%. These findings underscore the efficacy of FRP reinforcement in improving the structural integrity and performance of glulam column-beam connections, offering valuable insights for the design and renovation of wood-based construction elements.
Traditional analyses of tunnel reliability, which employ deformation values, such as surface settlement, crown settlement, and arch shoulder settlement, as instability indicators, fail to accurately depict the failure state of tunnel lining structures. In addressing tunnel instability induced by the failure of lining structures, the limit strain theory is introduced, designating shear strain penetration failure of the lining structure as the criterion for tunnel instability. A novel method for studying tunnel reliability, integrating neural network response surface methodology and Monte Carlo simulation, is proposed. The feasibility of the limit strain theory in reliability analysis is validated through the calculation of instability probabilities for specific tunnel projects, offering a fresh perspective on tunnel reliability assessment. Sensitivity analysis of rock mass parameters reveals that an increase in the variability of these parameters elevates the probability of tunnel instability and the shear strain value at the arch waists. Among these parameters, the variability of the modulus of elasticity (E) exerts the most significant impact on the probability of tunnel instability.
Seismic performance is a critical consideration in the design and assessment of reinforced concrete bridges. Ensuring the structural integrity and safety of bridges under seismic loadings is essential to protect public safety and maintain the longevity of these vital infrastructure components. The objective of this research study was to evaluate the seismic performance of a multi-span reinforced concrete bridge located in Pan Borneo Highway Sarawak. The non-linear static pushover analysis provided valuable insights into the bridge's load resistance. It determined that the bridge could withstand a base shear force of up to 30,130.899 kN before collapsing, indicating its high structural capacity. The capacity curve analysis further demonstrated the ability of bridge to endure spectral accelerations of up to 4.44 g (43.512 m/s$^2$), indicating its robustness against high-intensity ground motions. In addition, the non-linear static time history analysis considered three ground motions and their effects on the bridge's structural performance. The study highlighted the bridge's sensitivity to different external forces, with varying responses observed under different ground motions. Notably, the recorded joint acceleration and displacement values were found to be within acceptable limits, ensuring immediate occupancy and life safety for bridge users. The research study successfully evaluated the seismic performance of a reinforced concrete bridge in Pan Borneo Sarawak using non-linear time history and pushover analyses. The results demonstrated the bridge's satisfactory capacity to withstand seismic loadings. The utilization of CSIBridge software provided valuable insights into the bridge's structural integrity and behavior under seismic conditions. These findings contribute to the advancement of bridge engineering practices.
In this study, the FLAC3D finite difference numerical software was employed to simulate a geotechnical engineering project, establishing scenarios with concrete and steel pipe piles for support simulation. The analysis focused on the reinforcement effects provided by different types of piles on the geotechnical project. It was found that the reinforcement effects on the soil varied significantly between the pile types. Under the support condition of concrete piles, the maximum soil settlement observed was 4.12 mm, with a differential settlement of 3.19 mm. For steel pipe piles, the maximum soil settlement was reduced to 2.38 mm, with a differential settlement of 2.19 mm, indicating a superior support effect compared to that of concrete piles. Stress concentration phenomena were observed in the piles, becoming more pronounced when pile-soil friction was considered. The substitution of concrete piles with steel pipe piles led to an intensified stress concentration phenomenon in the soil surrounding the piles. The soil undergoing support from concrete piles exhibited the largest plastic deformation, whereas soil supported by steel pipe piles showed less plastic deformation. Consequently, it is concluded that steel pipe piles provide a superior support effect over concrete piles in terms of geotechnical engineering reinforcement.
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