Theoretical Model and Shaking Table Experiment of Eddy Current–Enhanced Friction Pendulum Tuned Mass DamperDu, Jiandong; Du, Jiaoyan; Bao, Chao; Cao, Jixing; Yu, Ziying; Ma, Xiaotong; Lu, Jianning
doi: 10.1002/tal.2211pmid: N/A
Traditional pendulum tuned mass dampers (PTMDs) necessitate substantial vertical space, and conventional friction pendulum systems (FPS‐TMDs) struggle to balance low activation thresholds with adequate damping levels due to their reliance on friction forces. This study presents an innovative eddy current–enhanced friction pendulum tuned mass damper (ECEFP‐TMD), which capitalizes on eddy current damping to lower the activation threshold effectively. Simultaneously, incidental friction damping provides a complementary dual–damping scheme. We developed a robust theoretical model, underpinned by shaking table experiments, to demonstrate the ECEFP‐TMD's superior vibration mitigation. Findings reveal that eddy current damping not only diminishes the activation threshold but also streamlines the adjustment of damping levels. The integrated dual–damping mechanism substantially augments energy dissipation, thus reducing the acceleration response of structures subjected to seismic activity. Particularly, for FPS‐TMDs with minimal friction coefficients, the inclusion of eddy current damping substantially elevates seismic resilience, mitigating stick–slip behavior typically induced by excessive friction damping.
Inverse Eigenmode Modeling and Multiscale Seismic Analysis of Irregular Frame Structure by Shear Spring–Multifloor Mass SystemAkehashi, Hiroki; Watai, Kazuki; Kamoshita, Naoto
doi: 10.1002/tal.2215pmid: N/A
A modeling method of an elastic shear spring–multifloor mass system (MF system) based on the fundamental eigenmode and natural circular frequency of a full‐scale structural frame is presented. MF system has plural lumped masses as representative of single floor, and the lumped masses are connected by interfloor shear springs. MF system focuses on both global and local responses of the original frame, namely, the total displacement, the non‐uniform displacements of an identical floor and the member force distributions. Therefore, the alternative use of MF system to the original full‐scale frame leads to the accurate and rapid evaluation of the responses of the frame. The introduction of the coupled shear springs to the modeling formulation provides the coupled horizontal responses in the two orthogonal directions. In addition, the interstory shear force distribution of the original frame and that of the equivalent MF system correspond. The accuracy of the proposed method is investigated through numerical examples for in‐plan irregular frames.
Dynamic Response Prediction of a Cantilever Beam Under Different Boundary Constraints and Excitation Conditions Based on an Improved Physics‐Informed Neural NetworkZhang, Xinyu; Zhu, Hao; Xu, Wei
doi: 10.1002/tal.70002pmid: N/A
The cantilever beam structures, like wind turbine towers, space masts, solar wings, and high‐rise chimneys and buildings, are widely used engineering structures. It is crucial to fast and accurately predict their dynamic responses under complicated excitations. This paper establishes an improved physics‐informed neural network (PINN) called Fourier transformation‐PINN (FT‐PINN) for predicting the dynamic response of a cantilever beam subject to different boundary constraints and excitation conditions. The core idea of the FT‐PINN is to use the Latin hypercube sampling strategy for generating model training points and introduce multiple sets of control equations with different frequencies through Fourier expansion to achieve high solving accuracy and efficiency for partial differential equations. Two loss functions, including the mean square error and mean absolute error, are included in the FT‐PINN for comparison. Four test cases are designed to evaluate the performance of the FT‐PINN and classic PINN in solving dynamic equations of a cantilever beam structure with different boundary and excitation conditions. It is validated that the FT‐PINN model proposed in this paper has higher accuracy and efficiency than the classic PINN. This also provides a new approach for using PINN to handle local sharp gradients and complex high‐frequency problems in vibration equations.
Study on Mechanical Performance of Built‐In Octagonal Encase Steel Core Tube Fully Bolted Assembly CFSST Column Connection JointZhang, Yanxia; Liu, Jiahui; Zhang, Ailin; Li, Yanglong; Shen, Sen
doi: 10.1002/tal.70007pmid: N/A
This paper proposes a built‐in octagonal encase steel core tube fully bolted assembly CFSST column connection joint (OCFSST). The proposed static test study was carried out on this connection joint and the welded CFSST column connection joint (WCFSST), and the data were processed, analyzed, and compared in terms of hysteresis curves, skeleton curves, stiffness degradation, displacement ductility, bolt preload, strain changes, and the joint core area displacement angle. The average value of the horizontal bearing capacity of this joint is 5.60% higher than that of the welded CFSST column connection joint, which proves that this joint has better mechanical performance. The average difference of the hysteresis curves, skeleton curves, and stiffness degradation curves derived from finite element and test data is not more than 8.13%, which proves that the finite element simulation method is effective. In addition, octagonal encase steel core tube, self‐tapping bolts, and concrete have a good deformation co‐ordination property, which can ensure the safety and stability of the structure. The OCFSST meets the performance design goal of “strong joints, weak components” and can improve the site construction efficiency, which has a good prospect for application.
Identification of Full‐Field Wind Loads on Buildings Using Displacement Measurements and Smoothing Kalman Filter Under Unknown Input Without Direct FeedthroughYin, Chang; Yang, Xiongjun; Liu, Lijun; Yang, Sen; Lei, Ying
doi: 10.1002/tal.70000pmid: N/A
Current wind load identification methods are mainly based on structural acceleration responses, which require the installation of many accelerometers on structures, to identify fluctuating wind loads that are assumed as independent white noise processes. With the development of machine vision, structural displacement responses under wind loads can be noncontact observed. In this paper, an identification method is proposed for full‐field wind loads including both the fluctuating and mean wind components on buildings using only structural displacement observations. Wind loads are treated as unknown forces on buildings without the assumptions of independent white noise processes of fluctuating wind loads in current identification methods. To reduce the number of independent unknown wind loads to be identified, the spatial correlations of wind loads are first analyzed. Then, as displacement observation equation does not contain the unknown forces, the smoothing Kalman filter under unknown input without direct feedback (Smoothing KF‐UI‐WDF) algorithm is used for wind load identification. To validate the effectiveness of the proposed method, both stationary and nonstationary wind loads on a 20‐floor shearing building are identified, and the identification results are validated in both time and frequency domains.
A Numerical and Parametric Study on Metallic Double Corrugated Damper Directly Connected to CBF BracesKontoni, Denise‐Penelope N.; Ghamari, Ali
doi: 10.1002/tal.2213pmid: N/A
Although concentrically braced frames (CBFs) pertain to high elastic stiffness and strength, they suffer from low energy dissipation capacity. This dilemma is due to the susceptibility of the diagonal member of the CBF to buckling. On the contrary, adding passive metallic energy dampers, although improving the behavior of the system, imposes more cost to structure and more constructional complexity. To overcome the problem, in this study, an innovative shear damper is made of a double corrugated plate for the web and two flange plates, called double corrugated damper (DCD). The numerical results using the Finite Element Method (FEM) indicated that the proposed damper pertains to a suitable performance with stable hysteresis curves under cyclic loading without degradation in stiffness, strength, and energy dissipation. This is true just to a certain lateral deformation. Also, numerical results under the monotonic loading indicated that the proposed damper shows an overstrength, Ω, of more than 1.5 (as recommended by AISC), and thus, Ω = 2.5 was proposed for it. Although links are categorized according to the ρ$$ \rho $$ factor in AISC 341‐16, the results indicated that dampers with the same ρ$$ \rho $$ revealed different response curves. Also, using the proposed damper with a corrugation angle θ=30°$$ \theta ={30}^{{}^{\circ}} $$ instead of θ=90°$$ \theta ={90}^{{}^{\circ}} $$ leads to an increase in the ultimate strength and stiffness, respectively, between 12% and 19% and 6% and 13% related to the flange thickness tf$$ {t}_f $$. The effect of θ$$ \theta $$ on this damper's performance is greater on dampers with thin flange plates than on dampers with thick flange plates.
Research on the Seismic Performance of Concrete Compressed‐Flexural Members After Cumulative Damage From 100 Years of Design UsageLiu, Hui; Liu, Ming; Yang, Xintian; Wang, Lin; Liu, Jie
doi: 10.1002/tal.2205pmid: N/A
This study investigates the long‐term effects of cumulative damage on concrete members over a century, emphasizing its critical inclusion in design protocols. Employing both static and dynamic experimental approaches, the research first examines the fundamental mechanical properties of damaged concrete at the material level. Earthquake intensity data from Northeast China are then analyzed to establish the frequency of predominant intensities over a 100‐year timeframe. Subsequently, four frame columns are exposed to cumulative pseudodynamic seismic damage, followed by pseudostatic testing to assess their seismic resistance. The results demonstrate that repeated sub‐cracking‐stress damage increases concrete's uniaxial compressive strength while reducing its ultimate deformation capacity. For elements with a low axial load ratio, minor seismic damage minimally impacts ultimate deformation but enhances ultimate bearing capacity, with the steel reinforcement reaching yield at an earlier stage. In contrast, for elements with a high axial load ratio, minor seismic damage has negligible effects on both ultimate deformation and bearing capacity, though it still accelerates the onset of yield in the steel reinforcement.
Predicting Compressive Strength of Oil Well Cement Slurries: Novel Moduli‐Based Analysis of Chemical Composition at Different Temperature ConditionJamal, Mohammed Ariwan; Mohammed, Ahmed Salih; Ali, Jagar A.
doi: 10.1002/tal.2214pmid: N/A
This study evaluates the impact of cement chemical composition on the compressive strength (CS) of cement slurries, utilizing silica fume (SF) and fly ash (FA) as additional materials. A comprehensive analysis was conducted on 317 datasets from the literature, focusing on factors including silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), calcium oxide (CaO), iron oxide (Fe₂O₃), water‐to‐binder (w/b) ratio, and SF and FA content, as well as curing time and temperature. The research presents three geochemical moduli, namely, silicate modulus (SM), aluminate modulus (AM), and hydraulic modulus (HM), to assess and forecast CS. The investigation utilizing full quadratic (FQ) and cubic (CUB) models underscores the precision of prediction models corroborated by statistical metrics, such as scatter index (SI), root mean squared error (RMSE), and correlation coefficient (R2). Univariate, bivariate, and multivariate evaluations indicate that SM, AM, and HM significantly decrease input parameters while preserving or enhancing model accuracy. The ideal replacement percentages for SF and FA to maximize strength were determined to be 14.6% and 11.6%, respectively. The optimal values for SM, AM, and HM were 2.62, 1.38, and 2.21, respectively. The results establish a solid framework for optimizing cement formulations, presenting sustainable alternatives for improved mechanical performance and decreased material consumption in oil well cementing and building applications.