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Fast-Pixel-Matching Algorithm for Automated Shear Stud Welding Based on the Integration of 2D Drawings and Structured Light Cameras 41

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Fast-Pixel-Matching Algorithm for Automated Shear Stud Weldi...

41st International Symposium on Automation and Robotics in Construction, ISARC 2024

作者： Wang, Huiguang Deng, Lu Cao, Ran Guo, Jingjing College of Civil Engineering Hunan University China Hunan Provincial Key Laboratory for Damage Diagnosis for Engineering Structures Hunan University China

ISBN: (纸本)9780645832211

Due to the lack of depth information, using 2D drawings to guide robotic manufacturing is difficult, such as stud welding and drilling. In this paper, a new algorithm, Fast-Pixel-Matching (FPM), is proposed to provide depth information for precise point positioning based on 2D drawings and structured light cameras. Based on our experiment, the efficiency of the FPM process is found to be at least 20 times higher than the brute-force search (BFS) method. Also, we demonstrated that the algorithm can be applied to automated stud welding, where the efficiency of positioning can be significantly improved and the positioning accuracy of the proposed method meets the code requirements. © 2024 ISARC. All Rights Reserved.

关键词： Stud welding

Experimental Study on Progressive Collapse Behavior of Frame structures Triggered by Impact Column Removal

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SSRN 2024年

作者： Yi, Fan Yi, Wei-Jian Sun, Jing-Ming Zhou, Yun Zhang, Wang-Xi He, Qing-Feng College of Civil Engineering Hunan Provincial Key Lab on Damage Diagnosis for Engineering Structures Hunan University Changsha410082 China

In the research field investigating the progressive collapse of building structures, event-dependent collapse processes have gained increasing attention in analytical and numerical studies. Different events could cause varying effects on progressive collapse resistance. The alternate load path could be related to events, and the event itself could also lead to variations in load actions. However, experimental studies on reinforced concrete (RC) frame structures triggering structural column removal by the low-velocity impact have not been reported. Therefore, this paper performed an initial experimental study employing impact loading as the extreme event to investigate subsequent progressive collapse behavior of structures. Tests were conducted on six RC substructures consisting of a two-span beam and a structural column. Gravity loads were applied to the top of substructures, and a pendulum impact setup was utilized to remove RC columns by low-velocity impact. When the column underwent lateral failures, the downward force exerted by longitudinal steel bars of the column, before they fractured, pulled the two-span beam beyond the compressive arch action (CAA) stage, leading to a collapse process entirely different from their event-independent counterparts. The parametric study based on experimental results indicated that low-elevation impact and increase in the cross-sectional areas of column longitudinal bars detrimentally affected the performance of two-span beams resisting progressive collapse, while the increase in concrete strength of specimens partially improved the residual bearing capacity after impact column removal (ICR). Based on a dynamic model, a simplified calculation method is proposed for quantifying the downward force. © 2024, The Authors. All rights reserved.

关键词： Reinforced concrete

Direct Shear Test Study on Old and New Concrete

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SSRN 2023年

作者： Zhang, Wangxi Yan, Baoqi Ye, Yuan Yi, Weijian College of Civil Engineering Hunan University Changsha410082 China Hunan Provincial Key Lab on Damage Diagnosis for Engineering Structures Hunan University Changsha410082 China

The interface between new and old concrete widely exists in prefabricated concrete structures and structural reinforcement, and its shear-slip performance directly impacts member and structural stress performance and deformation capacity. This study aims to examine the influence of roughness density, roughness, roughness treatment, and rebar distribution on the shear performance of the interface by performing direct shear tests on 14 Z-type specimens without dowel bars and 10 Z-type specimens with dowel bars. The tests conducted show that specimens without dowel bars inside fail shear brittle, and the roughness density of the interface has the most significant impact on shear strength, followed by roughness, with minimal effect on the roughness treatment method;Shear ductile damage in specimens with dowel bars, an increase in the number of inserted bars at a uniform reinforcement ratio leads to an increase in the bond stiffness and shear strength and a decrease in the peak slip;The interface after rough chiseling has the most shear strength. The interface after broaching has the next highest shear strength, and the interface after grooving has the lowest shear strength. Increasing the roughness or designing dowel bars can increase the structure's strain coordination ability, which benefits the overall stress loading. Finally, finite elements were used to validate the test's reliability, and refined modeling of the grooved without dowel bars model revealed that the peak height correlates best with shear strength. Chiseling and other means of improving the valley depth of the concrete interface at the base level is still a better roughness treatment. © 2023, The Authors. All rights reserved.

关键词： Stress analysis

Energy-based dynamic parameter identification for Pasternak foundation model

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Earthquake engineering and engineering Vibration 2021年第3期20卷 631-643页

作者： Wang-Xi Zhang Wei-Lei Lv Jin-Yi Zhang Xiong Wang Hyeon-Jong Hwang Wei-Jian Yi College of Civil Engineering Hunan UniversityChangsha 410082China Hunan Provincial Key Lab on Diagnosis for Engineering Structures Hunan UniversityChangsha 410082China School of Civil Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Architecture Konkuk University120 Neungdong-roSeoul 05029Korea

Parameter identification of Pasternak foundation models(PFM)is never satisfactory,which discourages the application and popularization of *** the present study,an energy-based model to predict the dynamic foundation coefficients was proposed using the vibration kinetic energy and potential energy of a Pasternak foundation-rigid plate *** the basis of the Pasternak foundation,the relationship among the natural frequency,dynamic foundation coefficients,rigid plate configuration,and vibrating soil equivalent mass per unit area was *** obtain the natural frequencies of the Pasternak foundation-rigid plate system,dynamic tests were *** two or more dynamic test results of various rigid plates on a foundation,a set of equations of dynamic foundation coefficients was set up to directly identify the foundation coefficients and equivalent mass per unit area of vibrating *** feasibility of the proposed method was verified by comparing it with the outdoor and indoor test results and finite element analysis *** the proposed method is used to obtain the dynamic parameters,PFM can be generalized and applied more widely in engineering practice.

关键词： Pasternak foundation dynamic tests vibrating soil mass dynamic foundation coefficients dynamic characteristics

Field measurements for calibration of simplified models of the stiffening effect of infill masonry walls in high-rise RC framed and shear-wall buildings

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Earthquake engineering and engineering Vibration 2020年第1期19卷 87-104页

作者： Zhou Yun Pei Yilin Zhou Yi Hyeon-Jong Hwang Yi Weijian College of Civil Engineering Hunan UniversityChangsha 410082China Hunan Provincial Key Lab on Damage Diagnosis for Engineering Structures Hunan UniversityChangsha 410082China Key Laboratory for Green&Advanced Civil Engineering Materials and Application Technology of Hunan Province Hunan UniversityChangsha 410082China

As a type of nonstructural component, infill walls play a significant role in the seismic behavior of high-rise buildings. However, the stiffness of the infill wall is generally either ignored or considered by simplified empirical criteria that lead to a period shortening. The difference can be greatly decreased by using a structural identification methodology. In this study, an ambient vibration test was performed on four on-site reinforced concrete high-rise buildings, and the design results were compared with the PKPM models using corresponding finite element(FE) models. A diagonal strut model was used to simulate the behavior of the infill wall, and the identified modal parameters measured from the on-site test were employed to calibrate the parameters of the diagonal strut in the FE models. The SAP2000 models with calibrated elastic modulus were used to evaluate the seismic response in the elastic state. Based on the load-displacement relationship of the infill wall, nonlinear dynamic analysis models were built in PERFORM-3 D and calibrated using the measured modal periods. The analysis results revealed that the structural performance under small/large earthquake records were both strengthened by infill walls, and the contribution of infill walls should be considered for better accuracy in the design process.

关键词： high-rise building ambient vibration test model calibration infi ll wall seismic performance nonlinear dynamic analysis

Experimental Study on Bond Performance between Rebar and Grout and Confinement Effects of Grouted Sleeve Connections

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SSRN 2022年

作者： Han, Bing Huang, Yuan College of Civil Engineering Hunan University Changsha410082 China Hunan Provincial Key Lab on Damage Diagnosis for Engineering Structures College of Civil Engineering Hunan University Changsha410082 China

In this paper, 84 steel sleeve and ductile iron sleeve connection specimens were tested. The influence of critical parameters on the confinement mechanism of sleeve, and the bond performance between rebar and grout under confinement effect was studied. The following parameters were considered in the experiments: compressive strength of grout, bond length, rebar diameter, rebar yield strength, and grout thickness. Pull-out tests were performed to obtain the complete bond-slip curves. Transverse and longitudinal strains were measured to determine the distribution of confinement stress along the bond length. The following findings were observed during testing: (i) the confinement stress was not uniformly distributed along the bond length;(ii) the bond length, rebar diameter, rebar yield strength, and elastic modulus of the sleeve wall had significant effect on the confinement stress;(iii) the confinement stress, grout compressive strength, bond length, rebar diameter, and rebar yield strength had significant effect on the bond strength. At the end of this study, simplified formulas of predicting the average confinement stress, the bond strength, and the peak slip in grouted sleeves were presented. © 2022, The Authors. All rights reserved.

关键词： Bond length

Response probability distribution estimation of expensive computer simulators: A Bayesian active learning perspective using Gaussian process regression

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arXiv

arXiv 2024年

作者： Dang, Chao Valdebenito, Marcos A. Manque, Nataly A. Xu, Jun Faes, Matthias G.R. TU Dortmund University Leonhard-Euler-Str. 5 Dortmund44227 Germany College of Civil Engineering Hunan University Changsha410082 China Key Lab on Damage Diagnosis for Engineering Structures of Hunan Province Changsha410082 China

Estimation of the response probability distributions of computer simulators in the presence of randomness is a crucial task in many fields. However, achieving this task with guaranteed accuracy remains an open computational challenge, especially for expensive-to-evaluate computer simulators. In this work, a Bayesian active learning perspective is presented to address the challenge, which is based on the use of the Gaussian process (GP) regression. First, estimation of the response probability distributions is conceptually interpreted as a Bayesian inference problem, as opposed to frequentist inference. This interpretation provides several important benefits: (1) it quantifies and propagates discretization error probabilistically;(2) it incorporates prior knowledge of the computer simulator, and (3) it enables the effective reduction of numerical uncertainty in the solution to a prescribed level. The conceptual Bayesian idea is then realized by using the GP regression, where we derive the posterior statistics of the response probability distributions in semi-analytical form and also provide a numerical solution scheme. Based on the practical Bayesian approach, a Bayesian active learning (BAL) method is further proposed for estimating the response probability distributions. In this context, the key contribution lies in the development of two crucial components for active learning, i.e., stopping criterion and learning function, by taking advantage of posterior statistics. It is empirically demonstrated by five numerical examples that the proposed BAL method can efficiently estimate the response probability distributions with desired accuracy. © 2024, CC BY.

关键词： Active learning

Determination of Dynamic Amplification Factors for Small- and Medium-Span Highway Bridges Considering the Effect of Automated Truck Platooning Loads

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SSRN 2023年

作者： Ling, Tianyang Deng, Lu He, Wei Cao, Ran Zhong, Wenjie College of Civil Engineering Hunan University Changsha410082 China Hunan Provincial Key Laboratory for Damage Diagnosis of Engineering Structures Hunan University Changsha410082 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai200240 China

Automated truck platooning (ATP) has a good potential in energy conservation and carbon emissions reduction, yet it has raised a wide concern to the safety and performance of highway bridges. Accurately estimating ATP-induced load effects on highway bridges is necessary, since the estimation results play a crucial role in both bridge safety evaluation and traffic/ATP decision-making. While some ATP load-related assessments have been performed on some specific bridges, the dynamic load effects induced by ATP on highway bridges were generally simplified by multiplying the static load effects by code-specified dynamic amplification factors (DAF) which has not taken ATP into consideration. This simplification may not be reasonable, since the actual DAFs of a bridge can be significantly affected by specific ATP loads. In this study, the DAFs of highway bridges due to ATP loads are investigated through both theoretical analysis and numerical simulation. Several standard highway bridges with different cross-sections and span lengths and probable ATP loading scenarios are considered, and the influences of multiple factors are investigated, including the truck mass, the number of platooned trucks, and the road surface condition. Both theoretical and simulation results showed that highway bridges can be at risk of two types of resonance due to ATP loads. The resonance type of a bridge can be roughly identified by the span length. Specifically, bridges with span lengths shorter than 15 m may mainly be affected by steady resonance while bridges with longer span lengths may be at high risk of transient resonance. Both types of resonance can lead to increased DAFs for highway bridges, which may exceed the specified DAFs in bridge design codes. To accommodate ATP loads, proper DAFs are proposed as a supplement to the current bridge design codes. © 2023, The Authors. All rights reserved.

关键词： Trucks

Dynamical modeling and non-planar coupled behavior of inclined CFRP cables under simultaneous internal and external resonances

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Applied Mathematics and Mechanics(English Edition) 2019年第5期40卷 649-678页

作者： Houjun KANG Tieding GUO Weidong ZHU Junyi SU Bingyu ZHAO Hunan Provincial Key Lab on Damage Diagnosis for Engineering Structures Hunan University Department of Mechanical Engineering University of Maryland College of Civil Engineering Hunan University

A dynamic model for an inclined carbon ?ber reinforced polymer(CFRP)cable is established, and the linear and nonlinear dynamic behaviors are investigated in detail. The partial differential equations for both the in-plane and out-of-plane dynamics of the inclined CFRP cable are obtained by Hamilton's principle. The linear eigenvalues are explored theoretically. Then, the ordinary differential equations for analyzing the dynamic behaviors are obtained by the Galerkin integral and dimensionless *** steady-state solutions of the nonlinear equations are obtained by the multiple scale method(MSM) and the Newton-Raphson method. The frequency-and force-response curves are used to investigate the dynamic behaviors of the inclined CFRP cable under simultaneous internal(between the lowest in-plane and out-of-plane modes) and external resonances, i.e., the primary resonances induced by the excitations of the in-plane mode,the out-of-plane mode, and both the in-plane mode and the out-of-plane mode, respectively. The effects of the key parameters, e.g., Young's modulus, the excitation amplitude,and the frequency on the dynamic behaviors, are discussed in detail. Some interesting phenomena and results are observed and concluded.

关键词： inclined carbon fiber reinforced polymer(CFRP)cable bifurcation nonlinear dynamics internal resonance external resonance