Earthquake Engineering & Structural Dynamics最新文献

Research on the rocking response of rigid rectangular blocks has primarily concentrated on pre-overturning dynamics, whereas post-overturning kinematics and behavioral evolution remain underexplored. The overturning of rigid blocks can be conceptualized as a transformation between the rocking motions of two distinct blocks. Their slenderness ratios are reciprocals of one another, implying that a unified motion exists that integrates both rocking and overturning phases for blocks with distinct slenderness ratios, bridging these phenomena. This motion, defined as a tumbling motion, forms the core of this study. This article systematically investigates the tumbling motion of rigid blocks under pulse and sustained sinusoidal excitation. Six distinct tumbling motion modes are identified and characterized. The study further examines the distribution of tumbling motion modes across varying slenderness ratios and excitation types and summarizes the underlying evolution mechanisms among modes under differing conditions.

Seismic damage evaluation of urban water distribution networks (WDNs) is essential for improving infrastructure resilience and emergency response. However, conventional fragility models coupled with probabilistic seismic hazard analysis often fail to capture local failure mechanisms at pipeline intersections, and cannot address the complex soil–structure interaction and ground motion propagation effects. This study bridges this gap by developing a numerical framework that integrates spatially correlated ground motions, detailed finite-element models of segmented pipelines with various intersection types, and GIS-based visualization of seismic damage distribution. The framework explicitly accounts for axial and rotational joint failures, intersection-induced deformation amplification, and spatial heterogeneity in site conditions. Numerical results show that cross-shaped pipeline intersections, including T-shaped, 45°-crossed, and 90°-crossed configurations, exhibit peak joint openings approximately 1.4–2 times greater than those in straight pipelines. Moderate-to-severe seismic damage is observed for small-diameter pipelines in soft-soil areas near fault sources. These findings underscore the importance of capturing site-specific ground motion variability and joint-level mechanical behavior for realistic damage prediction of WDNs. The proposed approach provides a practical decision-support tool for engineering design, seismic retrofit, and risk mitigation planning of urban WDNs.

An experimental investigation on the semi-active response control of a smart base-isolated structure equipped with a magnetorheological (MR) damper is presented. The experiment is conducted considering a single-story superstructure, whereas the isolation system comprises a sliding mechanism and linear springs used as restoring devices. Importantly, the base-isolated structure is equipped with an MR damper installed at the isolation level. The force-deformation behavior of the MR damper is characterized experimentally, and the modified Bouc-Wen model is used to represent the behavior numerically. The energy-based predictive (EBP) algorithm is used as a control law to dictate/modulate the control action effected by the MR damper. The smart base-isolated structure is mounted on a unidirectional shake table and studied under earthquake ground motions. The results of the shake table tests conducted on the smart base-isolated structure are presented and compared with those of the numerical simulations. The results of the fixed-base and passively-isolated models are also presented. The findings of the study validate the practicability of the proposed semi-active control strategy to mitigate the dynamic response of base-isolated buildings. Moreover, the results of the experimental investigation demonstrate the merits of the EBP algorithm in mitigating excessive peak isolator displacement and residual isolator displacement under earthquakes.

Buckling-restrained braces (BRBs) in buildings are intended to protect the primary structure from seismic damage by dissipating earthquake input energy through plastic deformation of their steel cores. To maximize the energy dissipation, they are supposed to sustain large strain amplitudes, which also correspond to strain rates much higher than those experienced by the primary structural components under the dynamic excitation of earthquakes. Most of the cumulative plastic energy in the encased steel core plate converts to heat that accumulates to give rise to the steel core and the unbonding medium attached to it. To investigate the effects of strain rate during dynamic loading, this paper introduces an experimental campaign of twelve geometrically identical BRBs subjected to uniaxial cyclic loadings at various levels of strain amplitudes and strain rates until the core plates fractured. Specifically-designed assembled all-steel BRBs were used to ease the visual inspection of the core plates and the temperature monitoring during the loading. The results show that the moderate strain rates of 3.0%s⁻¹ to 18.6%s¹ had obvious effects on several important performance measures of the BRB specimens. They include the complicated variation in the peak forces, increased compression overstrength, and reduced cumulative plastic deformation capacities. Neglecting these effects may results in non-conservative design of BRBs.

Dynamic displacement measurement is critical for assessing the structural integrity of civil structures in the aftermath of seismic events. However, traditional contact sensors and current non-contact vision-based methods face persistent challenges in accuracy, deployment flexibility, and robustness under complex field conditions. To address these limitations, this paper proposes a novel hybrid method for vision-based target-free dynamic displacement measurement of civil structures under seismic excitation. Departing from single-algorithm approaches, the proposed method synergistically integrates template matching (TM) and optical flow (OF) through a dynamic interaction and fusion mechanism. The TM channel delivers robust pixel-level displacement estimation while the OF channel provides sensitive sub-pixel velocity. These channels interact dynamically, where TM-derived displacements dynamically optimize the OF window size in response to structural motion to balance measurement sensitivity and robustness. The system further employs Kalman filtering technique to fuse channel outputs, leveraging OF for a priori motion prediction and TM for a posteriori error correction, thereby mitigating individual limitations such as TM's quantization errors and OF's cumulative drift. The proposed method is experimentally validated on an outdoor cold-formed steel (CFS) wall system and further applied to the engineering scenario of dynamic behavior analysis of reinforced concrete (RC) building. The results have shown that the proposed method provides more accurate, robust and efficient dynamic displacement measurements and overcomes the limitations of single-channel measurements, thus making it promising for structural health monitoring (SHM) in civil engineering.

In recent years, Japan's major cities have undergone vigorous redevelopment, leading to the demolition of many existing buildings. A major challenge in this process is how to deal with the existing foundation piles, specifically, how to execute the removal of these piles and the subsequent backfilling. This Short Communication reports on the current situation in Japan. It first outlines the ongoing redevelopment efforts and provides an overview of common methods adopted for pile removal in Japan. It then presents a case study of actual pile removal and backfilling work, showing that the stiffness of the surrounding ground after backfilling, particularly within about 2 m of the removal location, tends to decrease to about 60%–80% of the original ground's stiffness. It further suggests that staged-construction analysis with advanced numerical codes has the potential to reasonably simulate the pile removal process. Finally, the article highlights future technical challenges, including how to account for the reduced stiffness near the backfilled zone and how to control the properties of the backfill material, particularly with respect to their influence on the horizontal resistance of piles during earthquakes. It also discusses how pile removal and backfilling methods can adapt to emerging concepts such as carbon neutrality and the circular economy. Specifically, it touches on the reuse of existing piles in new buildings and the option of leaving old piles in place rather than removing them.