Aiming at the problems of random failure position, large amount of steel cutting and excessive welding length of traditional cross-core concrete-filled steel tube buckling-restrained brace ( CSBRB), a new type of perforated cross-core concrete-filled steel tube buckling-restrained brace (PCSBRB) is proposed in this paper. The structure and characteristics of PCSBRB are introduced, and the calculation equation of basic mechanical parameters is given. Six groups of PCSBRB models with different opening parameters and one group of CSBRB models are designed, and the quasi-static finite element analysis is carried out by ABAQUS software. The effects of the structural rationality of PCSBRB, the opening ratio and the number of openings on the mechanical properties, energy dissipation performance, stress distribution, high-order deformation characteristics, in-plane instability of the opening section and the equivalent cumulative plastic strain of PCSBRB are studied. The analysis results show that the structure of PCSBRB is reasonable, and the bearing capacity and energy dissipation performance are similar to those of CSBRB. The yield area of PCSBRB is located in the opening section, which has the advantages of fixed-point yield and multi-point energy dissipation. The hysteresis curves of PCSBRB with reasonable design is stable, full and symmetrical. For PSCBRB with too small opening rate, the stress is concentrated at the limit hole, and the purpose of fixed-point yielding cannot be achieved. For PCSBRB with too large opening rate, the opening section is prone to in-plane instability, resulting in a decrease in the bearing capacity of PCSBRB. The opening rate of PCSBRB should be 33%~50%. When the total length of the opening section is 1500 mm, the number of openings is set to 4~8, and the performance is similar. Compared with CSBRB, PCSBRB has higher material utilization and lower welding cost.

The indirect identification of bridge frequencies through coupled vehicle-bridge dynamics is a critical area of research that underpins the health monitoring of bridges. Traditional methods in this domain, however, impose significant constraints on the parameters and operational velocities of the vehicles involved. These restrictions significantly hamper the real-world applicability of these indirect methods since they cannot be smoothly integrated into the analysis of standard vehicles in normal driving conditions. To bridge this gap in the literature and practice, the current study presents a pioneering approach that capitalizes on the dimensionless response of vehicles in transit to indirectly identify bridge frequencies. The research commences by formulating a set of dimensionless equations characterizing the motion of the vehicle-bridge system. From this theoretical groundwork, the study derives a system state equation and an output signal equation, both predicated upon an enhanced subspace identification technique. This study introduces an innovative equation that captures the dimensionless residual response signal from the dual axles of a single vehicle, incorporating temporal variances in the process. This methodological framework successfully negates the adverse impact of road surface irregularities, effectively sidestepping limitations linked to vehicle parameters within conventional subspace identification methods. The versatility of this approach allows for its application to any typical vehicle in motion across a bridge. Then, the study validates the practicality of the proposed indirect approach for the frequency identification of simply supported beam bridges using the dimensionless response of a dual-axle vehicle. Through rigorous numerical analyses, this study examines the influence of driving speeds, road surface conditions, and stochastic vehicle loads on the indirect identification of bridge frequencies. The results highlight the necessity of adequate load excitation to dependably identify bridge frequencies, especially for eliciting the higher-order modal vibrations of bridges, which are essential for accurately identifying modes at higher frequencies. Finally, empirical evidence is provided through field tests conducted on a high-pier simply supported beam bridge. By inputting the monitored dynamic contact force between the vehicle and bridge into the proposed enhanced subspace identification model, this study validates the feasibility and accuracy of this novel approach. The experimental results affirm that the short-time stochastic subspace identification(ST-SSI) technique effectively isolates the first two modal frequencies of the bridge, outperforming the multivariable output error state space(MOESP) method in identifying higher-frequency modes. This research substantially broadens the scope of bridge frequency identification to include standard vehicles within regular traffic flows, simultaneously improving the precision of frequency detection, especially for higher-order modes.

Grouted sleeve connections are widely used in precast structures due to their excellent connectivity and ease of construction. However, variations in local stiffness within the grouted sleeve region and the relatively weak integrity of the concrete interface at the joint have negatively impacted the seismic performance of precast structures. This paper systematically summarizes the seismic performance tests, theoretical calculations, and numerical analysis of grouting sleeve connection joints, precast assembled components, and precast overall structures. Firstly, this paper elucidates the basic structure and force transmission mechanisms of grouted sleeves while summarizing the critical factors that influence the mechanical performance of sleeve grouted connections. Secondly, the influence laws of the strengthening effect of grouted sleeves on the mechanical properties of precast assembled structures are analyzed. Additionally, the impacts of the arrangement patterns of grouted sleeves and grout defects on the seismic performance of precast structures are investigated. Meanwhile, the calculation methods for the bearing capacities (bending, shear, and torsion) of precast assembled structures connected by grouted sleeves are summarized. Finally, the modeling methods of numerical analysis models for grout sleeve splice and precast assembled components connection with grouted sleeves are analyzed. Based on these, the following researches directions need to be explored: stiffness compatibility between sleeves, steels, and concrete; grouting quality assurance and detection methods; unified constitutive model for grouting material; calculation method for the bearing capacity of precast structure with grouted sleeve connections considering grouted sleeves, concrete, and steels factors.

Humanity’s demand for nuclear energy has driven its development, yet the frequent occurrence of nuclear accidents has emphasized the crucial importance of safety. Earthquakes, especially near-field earthquakes, pose a substantial threat to the safety of large structures, such as nuclear power plants. Traditional seismic response analyses of nuclear power plants often depend on the assumption of vertical incidence of input motions. However, near-field earthquakes predominantly exhibit oblique incidence, resulting to more intricate and diverse effects. This paper realizes the simulation of obliquely incident ground motions by using the three-dimensional visco-spring artificial boundary method to build a comprehensive model of the nuclear containment structure and its surrounding soil. Subsequently, two typical input motions—P-waves and SV-waves—are selected and input into the model at varying angles of incidence to conduct an in-depth analysis of the seismic dynamic response of the nuclear containment shell. Based on the research results, it can be observed that the dynamic response of the nuclear containment shell under near-field earthquakes exhibits more complicated characteristics, which cannot be entirely captured by assuming vertical incidence of input motions. This finding emphasizes the significant impact of near-field seismic motion patterns on the dynamic response of nuclear power structures, providing quantitative insights and valuable references for the seismic design and optimization of similar projects.

The cost-effective ratio for the reinforcement of seismic damaged structures is proposed based on the estimated seismic economic loss and reinforcement cost. A performance-based optimal selection method is established. The cost-effective ratio and estimated repair time are adopted as quantitative indexes. Besides, the construction technology, construction time cost, and effect on building functions are qualitative indexes. The technique for order preference by similarity to ideal solution (TOPSIS) and combination ordered weighted averaging (C-OWA) were adopted as the mathematical method for optimal selection. Taking a certain typical concrete frame structure as the research object, based on the incremental dynamic analysis results of different seismic damage reinforcement schemes, a comparative and optimal selection study of the FRP reinforcement scheme, shock absorption reinforcement scheme, and seismic isolation reinforcement scheme for the seismic damaged structure was carried out. Results indicate that the proposed cost-effective ratio can provide a comprehensive and objective insight into promoting seismic performance from an economic perspective. Moreover, the performance-based optimal selection procedure can effectively provide a scientific basis for the construction decision-maker by combining objective situations and subjective willingness.

The pile-columns of frame piers is a widely used substructure in bridge engineering. The current seismic design specifications for bridges require the pile to remain elastic following the capacity protection principle. Therefore, identifying the sensitivity of various design parameters to seismic demands of the piles is an important prerequisite for the capacity protection design of the piles. For this purpose, based on a coupled soil-pile-structure finite element modeling method, the sensitive parameters of pile-columns of frame piers to pile seismic demand are studied. Firstly, distribution mechanisms of bending moment under different earthquake intensity are investigated, together with understanding the contribution of ground surface tie beam to withstand the pile-shaft bending moment. On this basis, standardized seismic demand indicators representing the maximum bending moment of the pile, the corresponding depth, and the recommended reinforcement range are proposed. The sensitivity of tie beam, pile, column and soil parameters to the seismic demands of piles is analyzed. Based on the sensitivity parameter definition standards derived in this paper, the high and low sensitivity parameters of the pile seismic demand are identified. The research results can provide a reference for the seismic design of bridges supported by extended pile-shaft frames with ground surface tie beams in cohesionless soils based on pile capacity protection principle.

To address issues such as excessive displacement and inadequate self-resetting capabilities in isolated bridges employing traditional double concave friction pendulum bearings, a novel iron-based shape memory alloy-double variable friction pendulum bearing (Fe-SMA-DVFPB) was developed. This bearing integrates the variable friction mechanism on the sliding surface with the superelastic properties of shape memory alloy. A constitutive model for the bearing is established, and its equivalent analysis model is determined through theoretical analysis and numerical simulation. Based on practical engineering considerations, isolated bridges with different types of bearings are designed, and their seismic performance under near-fault ground motions is analyzed. The results show that the maximum isolator displacements of the three types of isolation structures under pulse-type earthquakes are 2.1, 1.63 and 1.47 times greater than those under non-pulse-type earthquakes, respectively. Compared to DCFPB-isolated bridges, Fe-SMA-DVFPB-isolated bridges exhibit the maximum reduction in isolator displacement of 38.9% under pulse-type earthquakes and 13% under non-pulse-type earthquakes. Additionally, the maximum reduction in residual displacement is 93.5% for pulse-type and 83.1% for non-pulse-type earthquakes. The use of Fe-SMA-DVFPB significantly improves control over both relative displacement and residual displacement. The reduction in relative displacement and residual displacement in Fe-SMA-DVFPB-isolated bridge bearings is significantly greater than the increase in bending moment and shear force at the pier base. Fe-SMA-DVFPB can further enhance the post-earthquake resilience of bridges.

It is crucial to quickly and accurately assess the losses for post-disaster relief and reconstruction after earthquake disasters. This article focuses on the research of normalized business requirements for earthquake on-site disaster loss investigation and assessment. By establishing a unified earthquake on-site disaster loss investigation and assessment system, it optimizes the information transmission process at the earthquake on-site, improves the timeliness of earthquake information transmission, and achieves the flattening of survey data collection, analysis, and management. Through the implementation of functions such as calculating the earthquake damage index of sampling points, comprehensively evaluating the intensity map, and semi-automatically generating assessment reports, the system improves the efficiency of earthquake disaster response and the accuracy of disaster loss assessment, providing strong guidance and a basis for post-disaster reconstruction. At the same time, the accumulation and analysis of earthquake on-site loss investigation and assessment cases serve as a reference for future emergency response and risk assessment. Finally, this article also presents further research throughts and methods to gradually improve the system’s functionality, rendering it more practical and sustainable.

Real-time hybrid testing is an important test method for exploring the seismic performance of structures incorporating velocity-dependent components. However, current real-time hybrid tests encounter the challenge that the numerical substructure calculation efficiency fails to meet the real-time requirements, thereby restricting the application of this method in seismic tests of large-scale engineering structures. In order to improve the computational efficiency of the numerical substructures, a physical information neural network suitable for real-time hybrid testing is proposed, and a real-time hybrid testing method for neural network surrogate models is implemented. First, a neural network model was constructed based on different physical constraint equations. Then the seismic response of a two-story frame structure with a damper was numerically simulated by finite element software, and these simulation data were employed to train the network model. Finally, the trained physical information neural network was used to carry out real-time hybrid test simulation. The simulation results show that the physical information neural network has high prediction accuracy, among which the physical information neural network using resilience as the loss function has the highest accuracy. The real-time hybrid test method based on the physical information neural network agent model is feasible.

The construction of underground utility tunnels has developed rapidly, resulting in a large number of interchange utility tunnels, and the interchange nodes of the these tunnels are mostly cast-in-place as a whole. Due to the significant difference in lateral resisting stiffness in two orthogonal directions of the interchange utility tunnel, and the soil deformation is closely related to the buried depth of utility tunnel, the seismic response mechanism of the interchange utility tunnel is complex. In this paper, a response displacement method for the transverse seismic analysis of underground interchange utility tunnel is proposed. Taking a cross interchange cast-in-place utility tunnel as the research project, the load-structure model of the cross interchange utility tunnel is established via the response displacement method. The maximum relative deformation and its occurrence time between the layers of the interchange utility tunnel are studied, and the method in this paper is verified by the time history analysis method. Results indicate that for the underground interchange utility tunnel, the maximum relative deformation between the layers of interchange node does not occur simutaneously. Considering only the maximum relative deformation of the top slab and bottom slab of the interchange node may not be the most unfavorable condition for seismic analysis of the structure. It is necessary to calculate the maximum relative deformation between the layers of the interchange node to determine the most unfavorable condition of the overall structure. The method in this paper can accurately calculate the internal force and deformation response of underground cross interchange utility tunnel under seismic action, which is of reference value for the transverse seismic design of the underground interchange utility tunnel.