Resumen en Inglés:

Abstract This study presents a stage-wise sectional analytical model for reinforced concrete (RC) beams strengthened with carbon textile-reinforced concrete (TRC) under sustained loading. The formulation accounts for pre-cracking, partial unloading, residual curvature, and TRC activation under non-zero initial strain. The TRC layer is modeled with bilinear tensile behavior, while tension stiffening and residual tensile effects of cracked concrete are included. The model is validated using full-scale bridge beams after about 30 years of service, tested under realistic conditions. The strengthened beam shows an increase of about 25% in ultimate load and improved crack control, with crack width and spacing reduced to one-third to one-half of the control beam. Strain results confirm effective stress redistribution and high textile utilization. Predictions agree well with experiments, with discrepancies within 5–10%. Compared with design guidelines, Z-31.10-182 is closest, while ACI 549.4R-20 and CNR-DT 215/2018 overestimate capacity. The model provides a reliable framework for assessing TRC-strengthened RC members under realistic conditions.

Resumen en Inglés:

Abstract To investigate the mechanical behavior of frozen soil subjected to shaped charge jet penetration at different temperatures, a combined theoretical and experimental approach was adopted. In the theoretical part, based on the dynamic cavity expansion model, the dynamic penetration resistance of frozen soil at various temperatures under high-velocity shaped charge jet penetration was calculated by incorporating the constitutive model and equation of state (EOS) for frozen soil. The calculated dynamic penetration resistance was then integrated with the axial penetration model of the shaped charge jet and the radial cavity growth model to determine the penetration cavity profile formed by jet penetration into frozen soil at different temperatures. The dynamic penetration resistance was subsequently validated through experiments on shaped charge jet penetration into frozen soil at −6 °C. The results indicated that as temperature decreases, the dynamic penetration resistance of frozen soil increases significantly, while the cavity diameter decreases markedly. However, no obvious variation was observed in cavity depth.

Resumen en Inglés:

Abstract Conventional steel strand anchorages are unsuitable for fiber-reinforced polymer (FRP) materials. This study evaluates a new bond-type anchorage system for unbonded post-tensioned GFRP bars. Prestressing is applied through a steel strand housed within a component threaded onto an adapter connected to the live-end anchorage. Two concrete beams reinforced with two post-tensioned GFRP bars were tested. The bars in Beam 1 were prestressed to 45.1% of their guaranteed tensile strength, and those in Beam 2 to 27.5%. Concrete strains were monitored during and after prestressing, followed by four-point bending tests. The system effectively transferred the prestressing force with minimal losses and no slippage. Beam 1 exhibited a 13.7% immediate strain loss after the second bar was prestressed. Beam 2 was prestressed two times, with average losses of 6.4% and 15.6% on each side after the first bar was prestressed, and 5.0% and 8.0% after the second. After these immediate losses, the prestressing force remained stable. The anchorages performed effectively under bending, maintaining GFRP bars prestress even after concrete crushing.

Resumen en Inglés:

Abstract This study introduces, for the first time, a high-order three-dimensional quadrature element for the coupled membrane and bending analysis of plate and beam structures under static and free vibration conditions. The formulation combines high-order polynomial interpolation with quadrature-based numerical integration to accurately represent three-dimensional stress and displacement fields. Unlike conventional two-dimensional approaches, the proposed model accounts for through-thickness deformation, making it suitable for both thin and thick structures. Consistent formulations are developed for in-plane and out-of-plane behaviors, with natural coupling achieved within a unified 3D framework. Numerical examples demonstrate the accuracy, efficiency, and robustness of the element in handling complex boundary conditions and higher vibration modes for isotropic and functionally graded materials. The results show rapid convergence, strong agreement with reference solutions, and reliable prediction of natural frequencies. This work provides an effective tool for high-fidelity structural analysis using three-dimensional finite elements.

Resumen en Inglés:

Abstract A simple way to obtain numerically the lateral load capacity curve of a masonry wall is to consider it as a one-dimensional element and perform a finite element incremental analysis. Based on some assumptions concerning the normal stress distribution, the panel can be discretized into frame elements whose geometrical properties are evaluated from the portion of the cross-section subjected to compression. In the case of employing finite elements of constant cross-sections, satisfactory results are obtained only if the mesh is dense enough to accurately represent the change in the geometrical properties of the resisting portion of the panel cross-section. In this work, a finite element with a variable cross-section is employed, so the number of elements required for a reliable solution can be reduced. The proposed model is tested against some experimental results available in the literature. Results are in good agreement with reference curves, showing that the proposed model may be employed to assess the load capacity of masonry shear walls in a pre-design phase.

Resumen en Inglés:

Abstract The radius of jetting projectile charge (JPC) varies significantly from the head to the tail, resulting in the crater formed with a large and uniform radius when penetrating steel target. Current methods for calculating crater radius typically use the average radius without considering JPC radius distribution, leading to large errors in the calculation. Therefore, it is necessary to introduce JPC radius distribution when predicting JPC penetration and cratering. By incorporating the radius distribution in the calculation of JPC break-up time, the modified break-up time model was used to obtain the prediction model for penetration depth. Based on the current jet (JET) cratering theory, JPC radius distribution was introduced to derive the prediction model for crater radius of JPC penetration. The X-ray tests and numerical simulations were used to obtain the radius and velocity distribution of JPC. Finally, the prediction model was verified using data from static penetration tests and literature. The results show that the penetration depth calculated using the modified model had a small error compared to the test results, therefore, the modified model could predict the variation of the crater radius with the penetration depth. And the variation of crater radius was in good agreement with the tests, and accorded with the characteristics of uniform crater radius of JPC penetration. The findings have important guiding significance for JPC design and evaluation.

Resumen en Inglés:

Abstract Ground contact explosions cause limited deformation and crater formation, an issue critical for forensic explosion analysis and blast-resistant structural design. In this study, a multiscale numerical model based on the Coupled Eulerian–Lagrangian (CEL) method was developed in Abaqus/Explicit to model craters formed by contact explosions on the ground. The model was calibrated using controlled field tests on low-plasticity clay-silt (CL) soil with 1, 2, and 3 kg of TNT equivalent and validated using a vehicle-induced explosion in Elazığ in 2016 with approximately 2 tons of TNT equivalent. Soil behavior was defined using the Mohr–Coulomb plasticity model and explosive behavior using the Jones–Wilkins–Lee (JWL) state equation. Crater diameter, depth, depth/diameter ratio, and blast index were evaluated across three orders of explosive mass. Numerical results were consistent with field measurements; error rates were below 5% for small-scale and below 8% for large-scale explosions. As the explosive mass increases, craters become wider and deeper. The CEL-based approach provides a reliable tool for forensic explosion analysis and the evaluation of ground behavior under extreme loading.

Resumen en Inglés:

Abstract Suspension bridges experience significant stress cycles from wind loads, leading to fatigue damage. Traditional rainflow counting methods perform poorly under non-stationary wind loads, especially when stress responses exhibit abrupt state changes, often causing incomplete cycle identification or amplitude misjudgment. This paper proposes a Time-Domain-State Dual-Layer Rainflow Counting (TSD-RFC) method. The method decomposes the non-stationary response into multiple quasi-stationary segments, applying classical three-point rainflow counting within each segment to identify primary fatigue cycles. Additionally, for state transition segments, an independent cycle counting layer captures large-amplitude stress cycles induced by wind speed fluctuations. Compared with traditional rainflow counting, TSD-RFC identifies stress cycles more accurately, particularly in high-amplitude regions, and effectively distinguishes cycles caused by state transitions. In fatigue assessment at a wind speed of 20 m/s, TSD-RFC yields approximately 11.39% higher fatigue damage than traditional methods, demonstrating its clear advantage under non-stationary wind loads.