Cylindrical steel storage tanks play a vital role in petrochemicals, oil refineries, power plants, and storage systems for liquefied natural gas (LNG) and other hazardous materials. These structures are highly susceptible to local instability that can cause failure of the tank–liquid system and disrupt industrial operations. Ensuring their safety and reliability requires advanced dynamic modeling, seismic design, and structural health monitoring. This study investigates the seismic behavior of cylindrical storage tanks, focusing on fluid–structure interaction (FSI) and the nonlinear response to seismic base excitations. The study also conducts a parametric analysis to assess the impact of liquid levels and seismic input accelerations on sloshing dynamics and structural response. Results from the finite-element analysis (FEA) are validated against experimental test data, demonstrating strong agreement and confirming the accuracy of the finite-element (FE) modeling approach. The results indicated that the experimentally measured shear force was 47.30 kN, whereas the numerical model predicted 44.27 kN, corresponding to a percentage difference of approximately 6.4%. Findings from the parametric study revealed that the hydrodynamic pressure changed significantly as the applied peak ground acceleration (PGA) input values varied. Tanks subjected to 0.45g exhibited slightly greater deformations compared with 0.40g, whereas 0.31g produced similar responses to those at 0.40g. Hydrodynamic pressures reached 149.3 kPa at 0.45g, 94.6 kPa at 0.40g, and 76.3 kPa at 0.31g, indicating reductions of 36.60% and 48.69%. For Tank 3 during the 1940 El Centro earthquake, the maximum sloshing height reached 970 mm at 22.6 s for the 91% fill level, with lower volumes producing 780 mm at 16.3 s and 760 mm at 51.7 s. This research provides critical insights into the seismic behavior of storage tanks and offers practical recommendations for designing resilient systems that mitigate risks associated with seismic activity.

Rockfall seriously threatens the construction and operation safety of karst tunnel. Obtaining the damage characteristics of tunnels under rockfall impacts is of great significance to optimize the design of protective structures, but is still unclear. In this study, a bond-based peridynamic (BBPD) method taking the strain rate influence of failure criterion into account is proposed. The accuracy and effectiveness of the proposed BBPD method was verified by comparing it with two experimental tests. Further numerical analyses using the proposed BBPD method were conducted to identify the influence of factors, including the impact velocity and impact position, on the damage characteristics of protection measures of a karst tunnel under rockfall impact. Protection measures include the composite lining, the composite lining with reinforced arch, and the composite lining with reinforced arch and buffer layer. The results show that the structural damage index follows a three-stage growth rule, including rapid growth period, slow growth period, and gradual stability period. The impact velocity and position have a significant effect on the structural damage index. The higher the impact velocity and the closer the impact position to the structural vault area, the greater the structural damage index. Under the three protection conditions, the tunnel damage index basically meets the requirements from large to small: the composite lining > the composite lining with reinforced arch > the composite lining with reinforced arch and buffer layer. The advantage for damage index reduction is not obvious for polyurethane thicknesses over 2.5 m. Finally, a composite lining with reinforced arch and buffer layer is proposed, which can resist the impact of the rockfall with a mass of 7.5 t falling freely from 105 m.

Reinforced concrete (RC) frame joints with T-shaped columns are widely used due to the special cross-sectional shape, which makes the indoor space arrangement flexible. Frame joints with T-shaped columns are more vulnerable to damage under seismic actions. Hence, it is essential for research on their rehabilitation after earthquake damage. To investigate the effectiveness of hybrid fibers–modified reactive powder concrete (HFMRPC) in rehabilitating frame joints with T-shaped columns, in-plane quasi-static loading tests were conducted on four seismic damaged T-shaped column frame joints (i.e., cast-in-situ interior joint and exterior joint, prefabricated interior joint and exterior joint). The tests and analysis results indicated that using HFMRPC for replacement rehabilitation effectively enhanced the bearing capacity, displacement ductility, and energy dissipation of frame joints with T-shaped columns, thereby delaying the stiffness degradation in the late loading stage. Compared with the prerehabilitated specimens, the enhancements in peak load, ductility coefficient, and cumulative energy consumption of the rehabilitated specimens ranged from 10.2% to 26.4%, 22.0% to 47.0%, and 62.2% to 109.8%, respectively. The core area of the rehabilitated specimens exhibited a multicrack development pattern, in which the energy dissipation capacity of the core area was improved. Finally, a flexural capacity calculation method for frame joints with T-shaped columns is proposed based on GB 50367-2013 and JGJ 149-2017.

Debonding between the steel tube and concrete core is a critical defect in concrete-filled steel tube (CFST) columns, especially in slender members where accidental load eccentricities are likely to occur. Although both debonding and eccentricity are known to reduce structural capacity, their combined effects and potential interaction in slender CFST columns remain largely unexplored in the literature. This study addresses this gap by experimentally investigating the compressive behavior of slender CFST columns with slenderness ratios λ=16, 24, and 32, subjected to concentric (e=0) and eccentric (e=0.5) ratio axial loads. A total of 20 debonding and non-debonding specimens with varying steel and slenderness ratios were tested. Debonding was introduced by placing removable PVC sheets during casting, producing well-defined voids confirmed through nondestructive testing and internal inspections. Results showed that debonding and load eccentricity reduced axial capacity almost independently, with no relevant interaction observed. These findings suggest that for slender CFST columns, debonding can be treated as a separate strength reduction mechanism, independent of eccentricity. To interpret the experimental results, a simplified analytical model was adopted, assuming that the total axial capacity is the sum of the individual contributions from the steel tube and the concrete core. The model confirmed that in slender CFST columns, concrete confinement is limited, and axial capacity can be reasonably predicted without enhancement factors, especially when debonding and eccentricity are absent.

This paper investigates the seismic performance of T-shaped connected modular steel beam-column (TMBC) connections through experimental tests and numerical analysis. A comparative analysis was conducted between the experimental and finite-element models of three different geometric configurations of connections: SPC-1, SPC-2, and SPC-3. The results show that the experimental and numerical results are in good agreement. Subsequently a parametric study corresponding to 17 computational models was conducted to investigate the seismic performance of TMBC connections. The analysis focused on these parameters such as the height–thickness ratio (α) of the replaceable panel zone column (RPZC) flange plate, the height–thickness ratio (β) of the RPZC web, the height–thickness ratio (γ) of the RPZC flange, the width–thickness ratio (δ) of the RPZC stiffener, the width–thickness ratio (ε) of the T-type connector flange plate, the height–thickness ratio (ζ) of the T-type connector web, the width–thickness ratio (η) of the beam flange, and the height–width–thickness ratio (θ) of the beam web. The results indicate that changes in the thickness of the RPZC stiffener and flange plate significantly impact the connection’s stiffness, stress distribution, energy dissipation capacity, and bearing capacity. Finally, a new three-segment moment–rotation formula based on extensive parameter analysis is proposed. The findings of this study provide a theoretical basis for evaluating the seismic performance of such connections and serve as a reference and technical support for their design in practical engineering applications.

The shear-resisting capability of beam-column joints is crucial for the structural integrity of reinforced concrete (RC) buildings and infrastructure under extreme loading conditions, such as earthquakes. A detailed numerical simulation study can theoretically predict the mechanical performance of RC joints. This paper employs an enhanced bond-based peridynamics (BPD) method to investigate the mechanical performance of RC joints under reverse cyclic loading, effectively capturing both the overall response and localized damage. The model is able to simulate various failure modes of RC joint and evaluates the role of joint hoops in transferring shear force and controlling crack widths. Following the analysis, the paper further validates the effectiveness of the softened strut-and-tie (SST) model using the refined BPD model, detailly studying the tension tie function of the hoops and the compressive strut function in the cracked RC component. This study shows that the BPD model provides an effective approach for describing shear-resisting mechanisms.

Accurately predicting the ultimate shear strength of RC beams, especially those with intermediate shear spans, presents a significant challenge. This complexity arises from the intricate interplay of flexural and shear behaviors within these structures. Although extensively researched, the contribution of arch action to the shear strength of these beams has frequently been underestimated. This study reexamines and quantifies the shear force contribution from arch action in intermediate reinforced concrete beams by introducing the arch action coefficient, α. This coefficient is determined using two analytical approaches: the compatibility method and the differential method. Both methods are subsequently validated through experimental testing on reinforced concrete beams. To simplify the calculation of ultimate shear strength, α charts are developed through finite-element analysis, incorporating the influences of yield strength, stirrup ratio, longitudinal reinforcement ratio, and span-to-depth ratio on α. Furthermore, theoretical models have been developed to consider the combined contributions of concrete and stirrup in beam action calculations. Generally, comparisons between these combined theoretical predictions (for beam action) and numerical simulations (for arch action) against experimental results show strong agreement.

Nuclear infrastructures in seismically active regions are vulnerable to mainshock-aftershock sequences, while environmentally induced deterioration can further exacerbate the impact of such seismic events on structural performance over the service life. However, the life-cycle safety margin of nuclear structures under multihazard scenarios remains unknown. This study presents a framework for deriving the state-dependent fragility of structures subjected to the combined effects of long-term environmental exposure and sudden seismic sequences. In this proposed framework, to reduce the substantial computational cost of life-cycle fragility estimates, a new surrogate model is developed to capture the dynamic behavior of aging structures, which can fully integrate the multilevel heterogeneous data sets and exploit similarities across different deterioration levels. Furthermore, to extend the applicability of the active learning algorithm to a broader range of surrogate models, a novel generalized learning function is also proposed to adaptively select optimal training sample points during each iteration of a two-stage active learning procedure. Finally, to account for the dependence between various deterioration mechanisms and residual structural capacities, time-dependent two-dimensional limit state functions are introduced to evaluate exceedance probabilities. The proposed methodology is illustrated for an aging containment structure subjected to mainshock-aftershock sequences. The results highlight the necessity of considering multihazard threats in the life-cycle safety assessment of containment structures, and demonstrate that the proposed method achieves a satisfactory trade-off between efficiency and accuracy in handling life-cycle fragility problems.

Real-time hybrid simulation (RTHS) is widely used to evaluate the seismic performance of structures with significant local nonlinearities or those that are challenging to model at reduced scales. Traditional RTHS, however, often neglects both time-dependent and time-independent structural uncertainties, limiting its applicability in dynamic reliability analyses. This study addresses this limitation by integrating adaptive sampling with RTHS to evaluate global seismic reliability while accounting for time-dependent uncertainties. A novel two-stage adaptive sampling approach is proposed: the first stage identifies samples representing highly uncertain scenarios to improve prediction accuracy, while the second stage couples time-dependent and time-independent uncertainties across time intervals to estimate structural responses. By iteratively applying adaptive sampling to select new sample points and conducting corresponding RTHS experiments to obtain structural responses, a metamodel is developed to evaluate global structural performance throughout the life cycle. Validation results demonstrate the method’s accuracy in representing uncertainties and its effectiveness in conducting time-dependent reliability analysis with multiple failure criteria. This approach significantly reduces experimental costs while maintaining high precision.

This research examines the pull-through failure behavior of cold-formed steel (CFS) C-shaped purlin-to-rafter connections using a cleat angle. A total of 72 tests were performed to evaluate the influence of cross-sectional parameters, including cleat angle leg length, purlin thickness, cleat angle thickness, and screw head diameter. The experimental study employed a small-scale test setup to closely replicate loading conditions of the wind uplift forces. A full-field measurement technique, namely three-dimensional digital image correlation (3D-DIC) was used to capture strain contours and understand the failure mechanisms for the observed failure modes. Three distinct failure modes were identified: a rupture-type pull-through failure in the cleat angle; a bearing-type pull-through failure in the cleat angle accompanied by tearing failure in the web of the purlin; and a bearing-type pull-through failure in the cleat angle accompanied by shank failure of the screw. These failure modes varied according to the thickness of the cleat angle (tc), the thickness of the purlin (tp), the ultimate tensile strength of the material (fu), and the screw head diameter (dw). The results of the study concluded that existing design guidelines were unconservative in predicting the pull-through capacity. Therefore, a modified design equation to predict the pull-through capacity of cleat angles in C-shaped purlin-to-rafter screw connection is suggested. Additionally, guidelines to calculate the initial elastic stiffness of CFS C-shaped purlin-to-rafter screw connections using cleat angles are presented. Furthermore, a reliability analysis was conducted to propose appropriate resistance and safety factors for the suggested design equation.