External aircon units are widely used in various building structures; however, they may suffer from seismic damage if exposed to earthquakes frequently, owing to insufficient seismic measures. To evaluate the seismic responses of external aircon units, a common aircon unit is installed on a rigid steel frame bolted on a shake table. Free-vibration and shaking-table tests are conducted to obtain the dynamic parameters and investigate the seismic performances, using four motions generated in accordance to four different code protocols. The aircon unit is modelled with a spring-mass model in OpenSees, to verify the experimental results. The experimental fundamental periods of the braced aircon unit are 0.09 s, 0.10 s, and 0.07 s, in three directions, respectively, and the corresponding respective experimental damping ratios are 3%, 6%, and 4%. The spectral accelerations for UB-NCS and FEMA461-compatible motions are larger than those for the other two motions with different periods. The magnitude of component acceleration amplification (CAA) factor decreases with increasing input peak acceleration (IPA), particularly for IPAs > 0.30 g. The experimental CAA is significantly underestimated in ASCE 7-22. The acceleration and strain amplitudes generally increase with increasing IPA, throughout the shakingtable tests, while the displacement amplitude behaves diversely. The steel in the oblique strut yields at IPA = 0.3 g. The analytical results match those of the experiments, with acceptable errors. The seismic design provisions on aircon unit in ASCE 7 are suggested to be modified based on the information revealed in this work.

Humanoid robots have recently drawn increasing attention due to their anthropomorphic morphology, high de grees of freedom, and integrated multimodal sensing capabilities, and they have been explored in a range of robotics and engineering applications. However, their potential for structural health monitoring (SHM) remains largely unexplored. Current indoor SHM practices still rely primarily on manual inspection or on mobile robotic platforms with limited adaptability and flexibility, which constrains inspection efficiency and operational cov erage in complex indoor environments. Motivated by this gap, this study proposes RoboInspect, an end-to-end autonomous inspection framework that employs a humanoid robot for indoor inspection. RoboInspect comprises three key modules: (i) a reinforcement learning-based locomotion controller trained and deployed on humanoid hardware, (ii) an autonomous navigation and path-planning pipeline that leverages prior maps together with onboard perception, and (iii) a vision-based perception module for structural crack detection in indoor inspec tion scenarios. These modules are designed to operate in coordination to support repeated, goal-driven indoor inspection tasks. The framework is evaluated through two representative case studies conducted in a university building, covering first-floor common areas and a stair landing with an adjacent corridor. Under controlled exper imental conditions, the system demonstrates reliable autonomous navigation along predefined inspection routes and effective crack detection, with a minimum reliably detectable crack width of approximately 0.2 mm. These results provide preliminary evidence supporting the feasibility of humanoid robots as inspection agents for civil engineering infrastructure.

Conventional methods for synthesizing large-displacement compliant constant-force mechanisms (CCFMs) are limited by approaches that fix a single topology and apply local refinements, which restricts the displacement range and increases force variation. To address these limitations, we propose the global topological exploration (GLOBE) method, a systematic approach that investigates a mechanism's global beam-path topology to identify topologies with enhanced performance. This topology-first approach is supported by a theoretical model that establishes a direct analytical link between global topological parameters, such as aspect ratio (AR) and number of turns (Nt), and the resulting bending compliance, which in turn determines the amplitude of the nearly zero-stiffness region. A multistart depth-first search (MS-DFS) algorithm first generates a comprehensive database of unique beam paths. These candidates then undergo high-throughput computational screening (HTCS) via nonlinear finite-element analysis (NL-FEM) to evaluate their performance against six dimensionless metrics. Experimental validation of a selected triangular topology confirmed a nondimensional displacement of 0.60. This was achieved with only a 2.69% force variation, closely matching computational predictions. The GLOBE method demonstrates that systematic exploration of global topology is essential for synthesizing large-displacement CCFMs suitable for applications in robotics, medical devices, and aerospace.

Inspection of glass curtain wall (GCW), especially under high-altitude working conditions, poses significant risks to human inspectors. To promote intelligent and automated inspection of glass curtain walls, the concept of a Hanging Basket Robot System (HBRS) is proposed for GCW inspection scenarios. Within the HBRS framework, the core motion-intelligence module, named VertInspect, is developed, enabling humanoid robots to execute inspection and maintenance tasks in a human-like manner. VertInspect consists of four components: (i) a video-based human motion recovery method to transform human motions from a monocular camera, (ii) a kinematics-based motion retargeting pipeline for mapping key human joint configurations to the robot's joint space, (iii) a reinforcement learning optimization algorithm for whole-body motion tracking, and (iv) deployment on a humanoid robot hardware to validate the tracking performance. Following the process of the glass curtain wall vibration test, three experiments are conducted, and four error evaluation metrics are evaluated. Each experiment is conducted for 15 trials, and the real-world tests achieve a success rate of 86.7%-100%, showing the reliability and effectiveness of VertInspect, which paves the way for the applications of HBRS in high-rise building inspection scenarios.

Building nonstructural components (NSCs) are attracting more and more attention for its enormous construction cost and huge potential loss under earthquakes. Floor acceleration or floor spectral acceleration is one of the critical seismic demands of acceleration-sensitive NSCs. Constant values or equations according to structural types, stories are usually used as a design value for floor acceleration amplification (FAA) factor in current codes in various countries. However, these values have not been validated by high amplitude records, where the acceleration may change its probabilistic distribution. This study establishes a dataset including 33 buildings and 175 floor motions, and the critical parameters such as distribution of floor acceleration along the structural height, mean value and distribution of acceleration amplification factor at the roof, normalized floor spectrum, and other key factors influencing the floor spectrum are analyzed. The results indicate that the FEMA P-58 equations for floor acceleration are generally applicable but suggest adjustments to higher amplification factors especially in steel frame structures. A constant value of 2.70 with an 84% confidence interval is suggested for code-oriented design, and probabilistic distribution of floor acceleration should be considered. The peak period of the floor spectrum could occur near either the fundamental period of the structure or the ground motion's predominant period, and the amplification factor of floor spectral acceleration over ground spectral acceleration at structural period could be set to 10.

Various and diverse stone curtain walls serve as typical building facades in civil buildings, which were mainly composed of stone panels and supporting frames, have been widely used in various civil buildings around the world. During long-term service life, stone curtain wall might be subjected to earthquakes, strong winds, environmental changes and other effects, resulting in performance degradation. At present, the monitoring and sensing methods of stone curtain wall panel’s safety and function states are always restricted at application level, and some safety hazards and functional degradation are hardly predicted with efficiency and accuracy, probably resulting in damage accidents, economic losses and negative social impacts during service time. In this paper, multi-source data were achieved through multiple monitoring means, characteristic parameters of mechanical and modeling dimensions were extracted, and the safety and functional performance evaluation of stone panels were investigated. Firstly, vibration signal data were collected by installing acceleration sensors on the curtain wall panel and supporting frame, and image data were analyzed by taking photos with high-definition cameras and drones. Then, the natural vibration frequency and crack length of the mechanical dimension, as well as the crack area and stain area of the molding dimension were extracted and analyzed. Finally, based on the monitoring data, the feature parameters in three dimensions were extracted to evaluate the safety and functional performance of stone panels. The safety and functional performance evaluation method based on multi-source data of stone curtain wall panel is more comprehensive and reliable than traditional methods, which can provide an innovation approach to evaluate and ensure the functional and safety performances of stone curtain wall.

To enhance the seismic resilience of historical and cultural heritage sites, protective measures were implemented through the installation of advanced heritage protection platform facilities. A structural health monitoring system was developed to safeguard historical relics during construction activities by continuously monitoring the overall condition of the relics and the integrity of critical components. Key parameters, such as settlement differences, tilt, crack width, and acceleration, were meticulously tracked, with predefined warning and alarm thresholds established. Alerts were triggered whenever these parameters exceeded their respective thresholds, ensuring timely interventions. To ensure the reliability and consistency of the collected data, this study proposes an evaluation method that integrates multi-source data fusion with statistical analysis techniques. Building on this foundation, an unsupervised algorithm was employed to identify construction activities impacting the structural health of the relics. The results demonstrate the effectiveness of combining multi-source data and intelligent algorithms for reliable monitoring and early detection of risks during conservation. The developed system offers automated, real-time assessments and can serve as a model for future heritage protection projects. Looking forward, integrating wireless sensors and diverse data sources could improve system accuracy, efficiency, and cost-effectiveness, further enhancing the protection of cultural heritage.

Recently, interest in automatic detection on glass curtain wall (GCW) inspection has been increasing, with the continuous innovation of robotics and artificial intelligence, the integration of cutting-edge technologies into construction scenarios is becoming increasingly feasible. To address the limitations of manual inspection, this study proposes deploying a humanoid robot in GCW inspection scenarios to mitigate high-altitude operations risks and improve efficiency. In order to enable humanoid robots to generate inspection motions like engineering technicians, a whole-body control method for imitating behaviors from raw monocular videos to robot motion generation is presented. Following the vibration test process, a detection standard for glass curtain wall is applied to demonstrate the feasibility and effectiveness of the proposed inspection framework. To improve control stability, the whole inspection motion is decomposed into three typical subtasks: arm-swing, tapping, and squatting. Firstly, three motion videos are recorded and extracted to get motion data. Secondly, the extracted motions are aligned with humanoid robot kinematic structure through a motion retargeting pipeline. Finally, a reinforcement learning-based optimization algorithm is adopted to track the robot joint reference trajectories. The success rate of each experiment consistently maintains 100%, validating the effectiveness of the motion tracking performance and highlighting its potential for practical application in glass curtain wall inspection tasks.

Under the earthquake, the lead core of lead-rubber bearings (LRBs) occurs plastic deformation which causes the temperature rise of the lead core. This temperature rise results in the yield stress degradation of the lead core, which in turn reduces the heating rate of the lead core. Thus, there is a significant coupling effect between the thermal and mechanical behavior. In this study, a new hysteretic model of LRBs considering coupled thermal and mechanical behavior was proposed. Firstly, a full-scale LRB was experimentally investigated to display the thermal and mechanical behavior. The monitored temperature rise in the lead core reaches nearly 100 degrees C within 40 s. Subsequently, a finite element model for thermal analysis was developed and calibrated to obtain the bulk temperature of the lead core. A prediction formula for the bulk temperature of the lead core was modified based on discussions on previous assumptions. Finally, a new LRB model based on the Bouc-Wen model was proposed and it can capture the coupled thermal and mechanical behavior simultaneously. A case study of an isolated building was further performed to explore the differences between the new model and Bouc-Wen model. The temperature rise of the lead core reaches 139 degrees C under the rare earthquake. The differences of seismic responses indicate that compared to the new model, the traditional Bouc-Wen model may overestimate the bottom shear force of the superstructure but significantly underestimate the bearing deformation under ground motions with long durations.

In this study, exterior dampers, including concentrated or distributed damping, were proposed and used to mitigate the wind-induced vibration of cable net fa & ccedil;ades. Firstly, a detailed practical finite element (FE) model was developed, with cooperative interactions among the cable nets, connecting claws, fa & ccedil;ade panels and dampers. Secondly, the impacts of dampers on the modal damping ratios, frequencies and mode shapes of the structures were analyzed. Lastly, by studying the dynamic time courses of the panel stresses, displacements, and cable forces, the vibration mitigation performance of cable net fa & ccedil;ades with concentrated and distributed damping under wind loads were investigated and compared. The results indicate that the damping ratios of the first three modes increase with the peaking of the damping coefficient of the damper. For the structure with concentrated damping, the maximum value of the modal damping ratio increases as the layout approaches the mid-span position. Moreover, the maximum value of the modal damping ratio for the structure with concentrated damping is larger than that with distributed damping. When the modal damping ratio of the structure reaches maximum value, the vibration mitigation rates of the structure with concentrated damping for the panel stress, displacement, and cable force are 12.6 %, 11.5 %, and 11.9 %, respectively. By comparison, the structure with distributed damping achieves mitigation rates of 5.8 %, 6.2 %, and 6.8 % for the panel stress, displacement, and cable force, respectively. The structure with concentrated damping demonstrating markedly superior performance compared with the structure with distributed damping. Therefore, unless aesthetic considerations are paramount, a cable net fa & ccedil;ade with concentrated damping should be prioritized for vibration control methods. This research provides a perspective on vibration mitigation for cable net fa & ccedil;ades.

Under the cyclic loading, the characteristic strength of lead-rubber bearings (LRBs) is reduced, resulting in the decrement of the key mechanical properties of LRBs, such as the stiffness and dissipated energy. This reduction is caused by the yield stress degradation resulting from the heating effect of the lead core. In this research, a methodology comprising experimental analysis, simulation, and formula derivation is proposed to investigate the temperature dependence of the yield stress degradation of the lead core. A comparative full-scale experimental study was conducted between the rubber bearing (RB) and the LRB to obtain the thermal and mechanical contributions of the lead core. The temperature test data under the cyclic loading inside the lead core was successfully recorded. To overcome limitations of the spatial sparsity of test data, a numerical model was developed to simulate the temperature field of LRBs and calculate the average temperature rise of the lead core. The results from the tests and simulations show that the yield stress degradation of lead core displays a significantly temperature dependency, a 75 % reduction accompanied by a temperature rise of 100 degrees C. Based on experimental and numerical results, a formula for accurate description of the temperature dependency of the yield stress degradation was proposed. There is only a single variable (the temperature rise) in proposed formula, thus it is convenient to be employed in practice.

Self‐heating effect of the lead core in lead–rubber bearings (LRBs) under cyclic loading causes degradation of mechanical properties of LRBs, which in turn affects their self‐heating effect. This study conducts full‐scale tests and proposes a numerical modeling methodology to investigate the coupled thermal and mechanical behavior of LRBs. The methodology integrates mechanical modeling, thermal modeling, temperature‐dependent material properties, and thermal‐mechanical modeling. Experimental results reveal significant mechanical degradation under high‐speed cyclic loading (0.25 Hz, 100% shear strain), with a temperature rise of 90°C in the lead core and a 22°C increase observed in adjacent rubber layers after 10 cycles. The numerical model demonstrates a good agreement with test data, accurately capturing force‐displacement loops and temperature within the lead core. Numerical results show that the thermal–mechanical behavior of LRBs is sensitive to loading frequency and shear strain: increasing the frequency from 0.25 Hz to 0.5 Hz amplifies energy dissipation rates by 38%, while a 50% increase in shear strain (100%–150%) increases peak temperatures by 27%. A case study under nonharmonic motion shows that conventional mechanical models overestimate energy dissipation by 37% compared to the coupled thermal–mechanical model. The proposed modeling methodology provides a usable tool for investigating the coupled thermal and mechanical behavior of LRBs under various seismic conditions.

Freestanding objects have endured seismic damage during major historical earthquakes, but their seismic performance is not fully understood yet. A steel frame was constructed with steel rods and moveable plates to investigate the effect of the center of gravity (CG) on the seismic response of nonstructural freestanding objects. The location of the CG can be tuned to change the CG in the frame. Two groups of shaking table tests were carried out using instrumented floor motion. To verify the shaking table test results, an analytical model was defined based on Housner's rocking model. The experimental response modes were predicted correctly. The experimental kinetic coefficient of friction obtained in the slow-pull tests agreed with the peak acceleration of the steel frame in the shaking table tests. The displacement amplitude generally decreased with increasing height of CG (hcg); however, this trend was not observed when the CG was fixed. Identical properties were observed for the rotational response of the frame. The experimental and analytical rocking responses were in agreement in terms of amplitude, but not in terms of time history and trajectories. The overturing criteria of overturing velocity, spectral velocity, and vulnerability, were evaluated using the experimental results. The overturning spectral acceleration was not accurately predicted using Housner's equation. The overturning probability and ratio were correctly predicted, and they increased with the increase in hcg. The findings of this work enable seismic risk mitigation of nonstructural freestanding objects.

Wind turbines are among the most rapidly increasing technologies for delivering sustainable energy. Good wind sites are usually found in rural regions, where thunderstorms and strong wind events are becoming more frequent and destructive, as a result of climate change. Downbursts are one of these events linked with thunderstorms which occur in a sudden and localized manner. One of the challenges in the analysis and design of wind turbines under downbursts is that, the associated forces acting on the tower and blades depend on the characteristics of the event including its size and location. The review of current design codes for this type of structures shows a lack of procedures for estimating the wind loading on wind turbines due to high intensity wind events, such as downbursts. The wind loads used in those design codes are based on large-scale wind events. In the current study, a comparative study is conducted using the previously developed numerical model, HIW-TUR, on a variety of wind turbines in order to assess the differences between current wind turbine design loads and downburst loads. HIW-TUR accounts for different downburst parameters, such as the size, jet velocity, and the location relative to the wind turbine center, as well as the change in the pitch angle of the blades. An extensive parametric study is conducted considering a large number of downburst configurations and different blade pitch angles. Moments at the tower base and the roots of the blades are obtained under different downburst configurations and are compared with those calculated using the International Electro-Technical Commission IEC 61400-1 [10]. Using the same reference velocity, downburst loads on wind turbines are found to be higher than the design loads, resulting in higher straining actions on the tower and blades.

This paper presents a novel asymmetrical self-locking mechanism (ASLM) and compact asymmetrical friction dampers (AFDs) designed to enhance serviceability in vibration control for structures. The proposed ASLM is based on frictional surfaces that are engage to provide the necessary damping feature. Simplified and detailed theoretical models are developed and utilized for the parametric study of the proposed damper. A comprehensive parametric study demonstrates a near-linear relationship between the slope angle of the AFD and its corresponding damping force when the slope angle is less than 45 degrees. Additionally, the proposed damper is fabricated based on the parametric study. Computational and theoretical models are also validated experimentally, with energy dissipation errors below 10%. Moreover, the practical applicability and effectiveness of the proposed AFD are evaluated by implementing it on a benchmark structure. Through non-linear time history analysis, a significant reduction of 17.2 % in interstory drift and nearly perfect in residual interstory drift are observed compared to the control group. These results highlight the potential of the novel ASLM and AFD to enhance vibration control efficiency in diverse engineering applications.

The cable-net supported glass facade(CSGF)is widely used in large public buildings.Due to its low damping,low stiffness,and strong non-linearity,the CSGF is subject to sudden changes in tension,excessive deformation,and panel damage under strong wind and seismic excitations.This paper established a refined numerical model of the CSGF system to quantify the effect of the adjacent main structures on the facade dynamic performance.The cable-net responses as well as the panel and sealant safety state under wind and seismic loadings were analyzed,and the calculated wind vibration factors were compared with the code reference values.The results show that the facade frequency considering the effect of main structures is reduced by an average of 12%.The peak displacement ratio of the central cable under seismic loading reaches to 6.5,much larger than that of the wind-induced response,indicating that the effect of main structures should be considered in the CSGF seismic response.For two hazards simultaneous excitation,the increase in cable-net displacement is greater than tensions,reflecting that the displacements are more sensitive to external excitation change.The top glass panel and sealant stresses have exceeded the design strength and should be paid more attention to during operation and maintenance.Moreover,the CSGF wind-induced response results are statistically analyzed to obtain the wind vibration factors for engineering design.

Normal isolator movement requires a wide isolation groove between adjacent base-isolated high-rise buildings, which is wasteful in terms of urban space. To solve this problem in China, large podiums are used in base-isolated multi-tower high-rise buildings. However, implementing the design procedure involves numerous difficulties. The podium needs to resist compression and shear forces due to significant differences in the dynamic characteristics of different towers. Other challenges include detailing the layout of the isolation system, selecting isolators to meet performance targets, analyzing the floor stress, and analyzing the temperature. The innovative base-isolation design procedures of multi-tower high-rise buildings with large podiums in highly seismic zones are validated. An ongoing project in Yunnan province, China, is taken as a case study, and the patented, high-performance rubber bearings for reducing the seismic response is used in this project, its effectiveness is verified through a series of experiments. This paper has guiding significance for similar engineering projects.

Under earthquake excitations, the lead core inside the lead-rubber bearing (LRB) generates heat, causing the mechanical degradation of LRBs. However, the heating effect is not commonly considered in the seismic analysis and design of base-isolated structures with LRBs, which may underestimate the seismic response of structures, especially under ground motions with certain specific characteristics. This paper aims to reveal the influence of ground motion characteristics on the heating effect and provide useful references for the seismic analysis and design. In this study, the validated LRB model considering heating effect was employed in a base-isolated building calibrated by testing data. Ground motion characteristics including amplitude, duration, and frequency content were separated by spectrally equivalent and different records. The results indicate that the rate and peak of the lead core temperature rise are strongly correlated to ground motion characteristics. Seismic responses ignoring the heating effect are underestimated, and this underestimate varies as the amplitude, duration, and frequency content change and reaches up to 60% in the studied case. Note that seismic responses of the isolation system are more affected by heating effects than the superstructure, and the duration shows a more significant influence on the stiffness degradation of LRBs than the frequency content. It is strongly recommended that the required duration of ground motions should be raised and the low stories of the superstructure should be reinforced for isolated structures with LRBs. The significant duration indicator DS5-95 is more reasonable than DS5-75 in the analysis of the heating effect.

To avoid the bearing stress on the monolithic patch antenna sensor for material deformation sensing, the unstressed patch antenna sensor using multiple patch components has been proposed for easy deployment. A typical unstressed sensor utilizes the relative position between a shorted sub-patch and a radiation patch as the deformation-sensing unit. However, the electrical contact condition between two patches and copper rusting will affect the performance and reliability of the unstressed sensor during practical application. In this paper, the authors alleviate this effect by applying conductive grease between the shorted sub-patch and the radiation patch. The equivalent circuit of an unstressed sensor with a shorted sub-patch is established first. The different electrical contact conditions are regarded as different capacitors and resistances in this model. Both simulations and experiments are conducted to investigate the effect of different contact conditions on the sensitivity of the sensor. Furthermore, the authors conducted experiments on patch antenna sensor with a copper-coated surface that had experienced rusting. The finding reveals applying copper-containing conductive grease between the shorted sub-patch and the radiation patch enhances sensitivity and reliability of the sensor, resulting in an improvement of up to 32%.

Current three-dimensional (3D) reconstruction technique-assisted damage detection research focuses on identifying, classifying, and locating surface damage on concrete components, challenging to quantify the effect of the identified damage on structural capacity. This paper attempts to present a novel method based on the 3D reconstruction technique and numerical model updating to detect concrete spalling damage and evaluate the adverse effects of the detected damage on the seismic performance of reinforced concrete (RC) shear wall components. Through a new concept of information transition point matrix, the mapping relationship between the defective information concealed in the reconstructed 3D point cloud model of the inspected wall and the performance variation of its corresponding finite element model is established. Experimental results demonstrate that the newly proposed method can successfully locate the concrete spalling damage and quantify the bearing capacity variation of the inspected specimen, which has excellent potential for future applications in civil engineering.