Earthquake Engineering & Structural Dynamics最新文献

The dynamic behavior of structures equipped with a clutching inerter damper (CID) flexibly connected to the ground, referred to as CID-F, is investigated. First, the steady-state response of a single-degree-of-freedom (SDOF) system with CID-F under harmonic acceleration is analyzed and compared with that of a conventional CID system. Results show that CID-F provides a greater reduction in structural response. For a given inertance ratio and mass ratio, an optimal period ratio of the CID-F can be identified at which the peak harmonic displacement attains its minimum value. Under this optimal condition, the motions of the support mass and main mass are synchronized, allowing the CID-F to engage effectively and provide maximum damping and response reduction. The system is then subjected to seismic excitation modeled as stationary filtered white noise, and the comparison of root mean square responses of the SDOF system confirms that CID-F outperforms the conventional CID, again with an optimal period ratio that minimizes the response. Finally, the performance of the CID-F for an SDOF system is evaluated under four real earthquake excitations. The findings reveal that, although the CID-F is a tuning-dependent device, its effectiveness does not deteriorate in comparison to CID when subjected to real seismic motions. However, for seismic applications and from a practical standpoint, the conventional CID system may be preferred over the CID-F.

Recent strong earthquakes have severely damaged pile-supported wharves, disrupting maritime trade and causing substantial economic losses. To enhance seismic resilience, this study presents a resilient pile-supported wharf (RW) based on damage-control design. In the RW, isolators are installed at the tops of vulnerable piles to decouple horizontal pile-deck interaction. Within these pile-deck decoupling zones, passive dampers dissipate energy and limit deck displacements under multi-level performance objectives, ensuring rapid post-earthquake recovery. A large-scale (1:10) substructure shake table test was performed to compare the seismic responses of the RW to a conventional ductile wharf (CW) based on a batter-pile wharf case. The proposed substructure testing method eliminates massive soil boxes, allows high PGA excitation of large-scale wharf specimens, and accurately reproduces prototype seismic responses with errors within 30%. Experimental results show that the RW achieved a high-resilience performance target (R3) under CLE and MCE earthquakes. Compared to the CW, the RW maintained comparable deck displacements and achieved up to a 73% reduction in deck accelerations. RW pile stresses remained elastic, concentrating energy dissipation within decoupling zones, whereas the CW experienced plastic deformation in batter piles, corresponding to a lower (R0) performance target.

The increasing complexity of modern construction necessitates multiple transverse openings in reinforced concrete (RC) beams to accommodate utility pipelines, often requiring these openings to be placed closer to the column face. While prior studies have primarily focused on beams with a single opening, this work investigates the minimum allowable spacing between two transverse circular openings and their proximity to the column face. A combined numerical and experimental approach is adopted. Finite element analysis (FEA) is employed to simulate stress distribution, deformation behavior, and failure mechanisms under various opening configurations, based on reinforcement guidelines from previous research. The FEA models are validated against existing experimental data to ensure accuracy. Additionally, two T-shaped RC beam specimens with transverse circular openings are tested to assess the minimum clear distance from the opening to the column face. A modified plastic truss model is used to predict shear strength in beams exhibiting shear failure near openings, and its predictions are compared with both FEA results and experimental outcomes. Based on these findings, this work proposes practical design recommendations for the placement of transverse circular openings near the ends of RC beams.

An innovative uplift-restraint friction pendulum bearing (UR-FPB) was proposed to enhance the applicability of seismic isolation technology. Departing from traditional FPB, the UR-FPB integrates a friction set responsible for structural isolation and an anti-uplift set enabling the bearing to withstand tension. Three theoretical constitutive models describing the friction set were first derived. Corresponding numerical finite element models were developed in Abaqus. A full-scale UR-FPB specimen utilizing various friction materials was fabricated. Subsequently, three experimental investigations were conducted to characterize the bearing's hysteretic response, fatigue behavior under sliding, and uplift resistance under tension. Experimental and numerical results demonstrate excellent agreement with the theoretical hysteresis characteristics, validating the bearing's effectiveness in providing isolation and preventing uplift. This validation encompasses sliding sequences, force–displacement relationships, and parameter effects. Observations from fatigue testing reveal damage modes in the friction plates, including significant out-of-plane warpage, local tearing or fracture, wear debris, and plastic deformation in length, width, and thickness. Notably, the bearing maintains stable hysteretic behavior, indicating that friction plate degradation has a limited influence on the friction coefficient at the polished slider interface. In the tensile test, the bearing achieves an ultimate tensile capacity of 300 kN, with failure occurring via predefined shear fracture within the anti-uplift track. This result confirms the bearing's excellent uplift-restraint capacity against external tension loads. The development of this novel UR-FPB offers valuable insights for designing future uplift-prevention systems in aseismic applications.

Tension-leg submerged floating tunnels (SFTs) are significantly affected by earthquakes, which can act through boundary excitations, cable propagation paths, and seaquake-induced effects. In super-long tension-leg SFTs, where mooring cables are the dominant constraint, seismic energy transmitted along the cable paths poses a significant threat to safe operation. This study experimentally investigates the nonlinear dynamic behavior of a scaled tension-leg SFT segment model subjected to lateral seismic input via cable propagation paths. Structural response characteristics are analyzed under both harmonic and transient excitations, with particular emphasis on the effects of cable inclination and buoyancy-to-weight ratio (BWR). The results indicate that the nonlinear resonance mechanism is the primary mechanism responsible for the extreme displacement and cable force observed under lateral seismic input via the cable propagation path. Increasing cable inclinations enhances lateral seismic resistance, but angles exceeding 60° substantially reduce this beneficial effect. Configurations with reduced BWRs suppress overall vibration amplitudes but lead to amplified roll responses compared with higher BWR designs.

The frequency bandwidth expansion compound shaking table (FBECST), as a new type of seismic simulation shaking table, offers an effective approach for generating long-stroke and wide-band excitation. Nonlinear signal-based control (NSBC), which enables nonlinear compensation through the linear (transfer function) model of the controlled system, has immense potential for enhancing the performance of the FBECST. This paper proposes a novel NSBC method for the compensation control of a FBECST supporting a nonlinear specimen. The convergence and stability of the proposed method are analyzed by theoretical derivation. The implementation process is described, and the influence of filter configuration on stability and accuracy is discussed. Finally, the effectiveness and advantages of the proposed method are compared and verified with inverse compensation (IC) and offline iterative control (OIC) as baseline methods. A series of numerical and experimental results show that the waveform reproduction ability of the FBECST system with NSBC is better than that with IC. In addition, the accuracy of the proposed NSBC can reach or even exceed the OIC with only a one-time identification and design process. This work can expand the application scope of the NSBC and provide an effective compensation control method for the FBECST supporting a nonlinear specimen.