Influence of self-weight on size effect of quasi-brittle materials: generalized analytical formulation and application to the failure of irregular masonry arches

A new type of spherical node was used to design a laboratory-scale prototype of a six-leg lattice of steel tubes and concrete for application as a wind turbine tower. Repeated load tests were performed on the prototype tower for several weeks to evaluate its load-carrying capacity, deformation, energy consumption, stress distribution based on damage patterns, hysteresis curves, skeleton curves, strength, and stiffness degradation curves. The findings indicated that the prototype tower underwent thread damage to the high-strength bolts of the inclined web and weld damage between the inclined web and sealing plate. Although the stress differences between different measurement points were significant, the stress values were small at most of the measurement points. The maximum equivalent stress value was 294 MPa, which appeared in the middle layer of the BC surface. The P-Δ hysteresis curve had an inverse “S”-shape, and the bearing capacity was high. The maximum energy dissipation appeared in the 1.75 Δy loading stage. The peak load of the specimen can reach 376.2 kN, and the corresponding peak displacement is 37 mm. However, the average ductility coefficient was only 2.33, indicating little plastic deformation. The maximum strain of the tower column foot is 1800 με, and the force of the inclined web member in the middle layer is the largest. The strain of the transverse web bar increased significantly after the tower yielded, which contributed to maintaining the integrity of the structure.

Section: Specimen Designmentioning

confidence: 99%

“…by scaling the prototype tower with a ratio of 1:2.8 [35,36]. The laboratory-scale model of the tower is displayed in Figure 1, and the parameters of the prototype are listed in Table 1.…”

Section: Specimen Designmentioning

confidence: 99%

Design and Performance Study of a Six-Leg Lattice Tower for Wind Turbines

Li,

Wen

2024

“…On the other hand, microscale modeling [10][11][12][13] treats the material as a discrete system composed of particles and investigates the mechanical properties, fracture behavior, particle arrangement, etc., by simulating the interactions and movements between particles. For example, Micaela Mercuri et al [12] studied the fracture behavior and size effect of masonry dome structures through microscale modeling.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the adopted model can accurately reflect the size effect, leading to more precise and reliable results. By considering the influence of size [11,12] on structural behavior, the model allows for a more comprehensive analysis, ensuring that the obtained results are both accurate and safe. This consideration is crucial for engineering applications, as it enables a better understanding of the structural response under different size conditions and aids in making informed design decisions.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of a Masonry Arch Bridge with Initial Defects Based on Cohesive Elements

Zou,

Wang,

2023

Most of the existing masonry bridges have been in service for a significant duration, and as a result of construction limitations, these structures often exhibit intricate geometric defects. Furthermore, under prolonged loading conditions, the rheological behavior of rock can induce deformation in masonry bridges, leading to a continuously evolving stress state. Employing an idealized model for safety assessment frequently results in an overestimation of their load-bearing capacity. To accurately evaluate the load-bearing performance and remaining service life of masonry bridges, as well as to prevent safety incidents, this study employs a parametric approach to establish a two-phase numerical model of masonry bridges. In this model, cohesive elements are introduced to simulate the bonding relationship, while the distribution pattern of geometric initial defects is determined based on the theory of conditional random fields. Additionally, the rheological behavior of rock is incorporated through a custom-written Abaqus user subroutine. Building upon this foundation, the probability distribution of the load-bearing capacity of masonry bridges is reconstructed using the maximum entropy method with fractional moment constraints. The resulting outcomes are compared and validated against those obtained using the decomposition conditional correlation matrix. Finally, the effectiveness and applicability of the proposed method are demonstrated through numerical simulations and field measurements conducted on an actual bridge. The findings reveal that the method introduced in this paper adequately accounts for the stochastic nature of geometric initial defects, objectively reflects the operational performance of masonry bridges, and effectively simulates the complete failure process of such structures. Consequently, this method provides a solid basis for the safety assessment of masonry bridges.

“…In this paper, considering the limitations of model testing in tunnel engineering, we did not capture the size effect in this study [51]. However, the experimental results still comprehensively reveal the collapse mechanism of soil-rock composite strata with cavities, providing a reference for tunnel collapse prevention and control.…”

mentioning

confidence: 98%

Model Test on the Collapse Evolution Law of Tunnel Excavation in Composite Strata with a Cavity

Zhang,

Gao,

Wang

et al. 2024

More complex geological conditions could be encountered with the construction of urban subway projects. At present, many subway tunnels have been built in composite strata with upper soft and lower hard layers, but the presence of a cavity in the strata increases the risk of collapse during construction. In this paper, a series of model experiments and discrete element methods were conducted to investigate the failure behavior of composite strata with a cavity caused by tunnel excavation disturbance. The influence of the distance between the cavity and vault (hd) and the distance between the soil–rock interface and vault (hr) on the collapse of the composite strata are analyzed. The research results indicate that tunnel collapse exhibits progressive failure because of the forming of a collapsed arch in the strata. If the hd is greater than the tunnel span (D), the arch can be stabilized without other disturbances. Additionally, the thickness of the tunnel rock layer affects the height of the collapsed arch significantly, as it is difficult to form a stable arch when the hr is less than 2/3 D. Finally, reasonable construction safety distances are proposed based on the possibility of forming a stable arch collapse in the tunnel and determining the range of the collapse.