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6th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil structures, SMAR 2022

作者： Tang, Jianyang Song, Xiaobin Guo, Yu Song, Yinkai Department of Structural Engineering Tongji University Shanghai200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures Tongji University Shanghai200092 China

ISBN: (纸本)9789819933617

Drilling-induced residual strain of timber member around fastener holes (such as bolts) often leads to deterioration of mechanical properties. In this paper, the effects of diameter of holes (14, 18 and 22 mm), drilling speed (95 and 190 r/min) and wood species (Spruce, Spruce-Pine-Fir and Douglas Fir) on the residual strain of wood specimens were evaluated. The dimensions of the specimens were determined according to Standard Test Method for Evaluating Dowel-Bearing Strength of Wood and Wood-Based Products (ASTM D5764). Based on an open source 2D digital image correlation (DIC) MATLAB program, Ncorr, the drilled-induced residual strain around the hole was assessed by comparing the wood deformation for specimen before and after drilling. The results indicated that with the same drilling speed, the residual strain distribution of specimens did not vary remarkably with different hole diameters. The maximum residual compressive strain increased with increase of drilling speed, while it did not vary significantly with the hole diameter or wood species. The research provides theoretical guidance for improving the elastic—plastic analysis of mechanical behaviour of bolted timber connections. © Tongji University Press 2024.

关键词： Image correlation

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Degradation of Interfacial Behaviour Between AFRP and Concrete Under Sulfate Attack 6th

Degradation of Interfacial Behaviour Between AFRP and Concre...

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6th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil structures, SMAR 2022

作者： Zhao, Yi-Zhou Yu, Qian-Qian Department of Structural Engineering Tongji University Shanghai200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures Tongji University Shanghai200092 China

ISBN: (纸本)9789819933617

Sulfate attack is a kind of salt corrosion which causes deterioration of concrete structural properties. For fiber-reinforced polymer (FRP) strengthened concrete structures, it is also one of the significant factors affecting the bond behaviour between FRP and concrete. In this study, the effect of sulfate attack on the bond behaviour of Aramid FRP (AFRP)-to-concrete interface was investigated. The sulfate corrosion environment was simulated by the sulfate full immersion corrosion test. 15 single-lap shear specimens were prepared. The load-slip curve, bond strength and interfacial fracture energy of the specimens were analyzed. Results showed that, under the sulfate attack, the bond stiffness of the specimens increased while the slip at the turning points of the load-slip curve decreased;After exposure for 300 days, the bond strength and interfacial fracture energy decreased by 17.6 and 26.0%, respectively. © Tongji University Press 2024.

关键词： Deterioration

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Fatigue behavior of steel plates subjected to marine environment 12th

Fatigue behavior of steel plates subjected to marine environ...

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12th International Conference on Bridge Maintenance, Safety and Management, IABMAS 2024

作者： Chang, A. Yu, Q.Q. Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai China Department of Structural Engineering Tongji University Shanghai China

ISBN: (纸本)9781032770406

Fatigue refers to a phenomenon in which stress of metallic structures at failure is significantly lower than the yield strength after long-term periodic loads. Corroded steel structures characterized by reduced nominal cross sections and complex surface morphology are prone to fatigue damage, and have attracted much attention in the community of civil engineering. This study presents a comprehensive study on the fatigue behavior of corroded steel plates. Specimens were first placed in a neutral salt spray environment and then loaded by fatigue. Effects of different placement angles on the morphology and fatigue behavior of the steel plates were investigated. A 3D laser scanner was adopted to obtain the corrosion morphology and later applied in the numerical simulation. A three-dimensional finite element model was proposed to calculate the stress concentration factor (SCF) and strain concentration factor (SNCF) of the specimen. © 2024 The Author(s).

关键词： Morphology

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Proposing a development framework for sustainable architecture, engineering, and construction industry in China: Challenges, best practice, and future directions

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Frontiers of Structural and Civil engineering 2024年第5期18卷 805-814页

作者： Peixian LI Yujie LU Xuwen XIAO College of Architecture and Urban Planning Tongji UniversityShanghai 200092China Key Laboratory of Ecology and Energy Saving Study of Dense Habitat(Tongji University) Ministry of EducationShanghai 200092China College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghai 200092China China State Construction Engineering Corporation Beijing 100029China

China’s architecture,engineering,and construction(AEC)industry needs a clear and sustainable development *** inspiration from speeches delivered at a seminar hosted by the Chinese Academy of engineering and extensive literature research on Chinese policies,this article presents a summary of the current trends in the AEC industry in four dimensions:industrialization as the foundation,intelligence as the enabler,lean management as the strategy,and green development as the *** four dimensions are intricately interconnected and rooted in multiple *** article provides a detailed review of the current practices,challenges,and future directions associated with each ***,ten grand challenges were proposed to stimulate discussions on the future of the AEC *** article offers an overarching understanding of the AEC industry and presents a four-dimension framework for sustainable development,which can be valuable for AEC practitioners.

关键词： green building lean construction prefabrication smart construction sustainable development

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Research on Design Method of FRP Anchor in RC Columns Confined with Bidirectional FRP Sheets 6th

Research on Design Method of FRP Anchor in RC Columns Confin...

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6th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil structures, SMAR 2022

作者： Gao, Peng Chen, Zhonghui Yuan, Daming Wang, Tianyu School of Civil Engineering Hefei University of Technology Hefei230009 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai200092 China

ISBN: (纸本)9789819933617

In retrofitting the existing reinforced concrete (RC) frame structures, the improvement of seismic grade leads to the composite strengthening demands of columns. The bidirectional fibers reinforced polymers (FRP) sheets can be tensioned in two ways, and subsequently, the shear and flexural capacities of confined columns are simultaneously improved. In this article, the bidirectional FRP sheets with fiber anchors were designed and applied, and three specimens were tested under low cyclic lateral loading. The test results showed that the failure mode of the RC column changed after strengthening, the effective strain of longitudinal fibers in FRP sheets significantly increased when using fiber anchor, and the flexural capacity of the column was further improved. © Tongji University Press 2024.

关键词： Fibers

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Bond behavior of the interface between concrete and basalt fiber reinforced polymer bar after freeze–thaw cycles

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Frontiers of Structural and Civil engineering 2024年第4期18卷 630-641页

作者： Li HONG Mingming LI Congming DU Shenjiang HUANG Binggen ZHAN Qijun YU Department of Structural Engineering Hefei University of TechnologyHefei 230009China Key Laboratory of Performance Evolution and Control for Engineering Structures Tongji UniversityShanghai 200092China Engineering Research Center of Low-carbon Technology and Equipment for Cement-based Materials(Ministry of Education) Hefei University of TechnologyHefei 230009China Hefei Cement Research&Design Institute Corporation Ltd. Hefei 230051China

The shear bond of interface between concrete and basalt fiber reinforced polymer(BFRP)bars during freeze–thaw(F–T)cycles is crucial for the application of BFRP bar-reinforced concrete structures in cold *** this study,48 groups of pull-out specimens were designed to test the shear bond of the BFRP-concrete interface subjected to F–T *** effects of concrete strength,diameter,and embedment length of BFRP rebar were investigated under numerous F–T *** results showed that a larger diameter or longer embedment length of BFRP rebar resulted in lower interfacial shear bond behavior,such as interfacial bond strength,initial stiffness,and energy absorption,after the interface goes through F–T ***,higher concrete strength and fewer F–T cycles were beneficial for enhancing the interfacial bond ***,a three-dimensional(3D)interfacial model based on the finite element method was developed,and the interfacial bond behavior of the specimens was analyzed ***,a degradation bond strength subjected to F–T cycles was predicted by a proposed mechanical *** predictions were fully consistent with the tested *** model demonstrated accuracy in describing the shear bond behavior of the interface under numerous F–T cycles.

关键词： F-T cycle interface shear bond strength bond stress−slip curves bond degradation

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Model free optimization of building cooling water systems with refined action space

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Building Simulation 2023年第4期16卷 615-627页

作者： Qiaofeng Xiong Zhengwei Li Wenxia Cai Zhechao Wang School of Mechanical Engineering Tongji University ShanghaiChina Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghaiChina

Deep Q Network(DQN)is an efficient model-free optimization method,and has the potential to be used in building cooling water ***,due to the high dimension of actions,this method requires a complex neural ***,both the required number of training samples and the length of convergence period are barriers for real ***,penalty function based exploration may lead to unsafe actions,causing the application of this optimization method even more *** solve these problems,an approach to limit the action space within a safe area is proposed in this *** of all,the action space for cooling towers and pumps are separated into two ***,for each type of equipment,the action space is further divided into safe and unsafe *** a result,the convergence speed is significantly *** with the traditional DQN method in a simulation environment validated by real data,the proposed method is able to save the convergence time by 1 episode(one cooling season).The results in this paper suggest that,the proposed DQN method can achieve a much quicker learning speed without any undesired consequences,and therefore is more suitable to be used in projects without pre-learning stage.

关键词： building cooling water system cooling tower cooling water pump DQN controller convergence speed

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Effect of coarse aggregate on compressive mechanical properties of irradiated concrete 20th

Effect of coarse aggregate on compressive mechanical propert...

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20th fib Symposium on ReConStruct: Resilient Concrete structures, 2024

作者： Liu, Hui Zhang, Weiping Zhou, Yong Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University 1239 Siping Road Shanghai200092 China Department of Structural Engineering Tongji University 1239 Siping Road Shanghai200092 China

ISBN: (纸本)9782940643257

It is widely acknowledged that the radiation-induced volumetric expansion (RIVE) of aggregates is the primary mechanism responsible for the degradation of mechanical properties of concrete under neutron irradiation, while the effect of coarse aggregate on the mechanical properties of irradiated concrete remains to be further elucidated. In this study, the random aggregate model for irradiated concrete was established by the finite element method, and the free volume expansion and subsequent uniaxial compression loading of concrete specimens were simulated under experimental conditions involving nonuniform neutron fluence and temperature fields. Afterward, the simulation of cube-shaped concrete specimens under uniform neutron fluence and temperature fields was conducted. The numerical results show that under uniform neutron fluence and temperature fields, the relationship of elastic modulus and compressive strength with the aggregate linear expansion is consistent for irradiated concretes with different coarse aggregate contents. The concrete linear expansion is linearly related to aggregate linear expansion, and the slope of the linear relationship increases with the increase of coarse aggregate content. Besides, the evolution patterns of linear expansion, elastic modulus, and compressive strength with neutron fluence for irradiated concretes with different maximum particle sizes of coarse aggregates are identical. © fédération internationale du béton (fib).

关键词： Compressive strength

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Statistical investigation on sulfate ions distribution in concrete based on mesoscopic modelling 20th

Statistical investigation on sulfate ions distribution in co...

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20th fib Symposium on ReConStruct: Resilient Concrete structures, 2024

作者： Feng, Jinyang Song, Xiaobin Zhang, Weiping Key Laboratory of Performance Evolution and Control for Engineering Structures of the Ministry of Education Tongji University 1239 Siping Road Shanghai200092 China Department of Structural Engineering Tongji University 1239 Siping Road Shanghai200092 China

ISBN: (纸本)9782940643257

External sulfate attack is one of the main reasons responsible for the performance deterioration of concrete. Accurate prediction of the temporal and spatial distribution of sulfate ions in concrete is the basis for revealing the mechanical performance evolution of concrete structures caused by sulfate attack. To investigate the random characteristics of sulfate ions distribution in concrete caused by the random distribution of coarse aggregates, a two-dimensional mesoscopic numerical model is introduced, in which the concrete is regarded as a two-phase composite material, including mortar and coarse aggregates. The probability characteristics of sulfate ions distribution were identified based on statistical analysis of the mesoscale simulation results. Furthermore, the effect of the shape and size of coarse aggregate on the distribution of sulfate ions concentration was analyzed. The results demonstrate that the mean concentration of sulfate ions was hardly affected by the shape and size of coarse aggregate. The coefficient of variation increased with an increase in the aspect ratio of coarse aggregate, whereas the effect of aggregate angularity and size can be ignored. © fédération internationale du béton (fib).

关键词： Concrete aggregates

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Design and Experimental Study of Novel controllable Attenuator Systems for Constant Temperature Air-Conditioning 18

Design and Experimental Study of Novel Controllable Attenuat...

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18th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2024

作者： Weichen, Guo Yusong, Hong Zeng, Wang Xuejin, Zhu Zhe, Zhu Wei, Ye School of Mechanical Engineering Tongji University Shanghai China Shanghai Architectural Design and Research Institute Co. LTD Shanghai China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai China

ISBN: (纸本)9798331306816

High-end manufacturing and fundamental physics research require the provision of indoor air environments with ultra-high precision constant temperature. Therefore, the chilled water system, which is the main source of cooling, also requires strict temperature control. Current closed-loop control loops are mainly used to overcome low-frequency disturbances, and attenuators are usually used to overcome high-frequency fluctuations. In this study, two high-precision controlled attenuator systems based on two typical attenuators, i.e., plate heat exchanger and water mixing pump, were proposed, which combined PID control and attenuator through flow control to achieve full-frequency fluctuation control of fluid temperature. Experiments on controlled attenuator operation under two schemes were carried out. And the Fourier transform was used to calculate the fluctuation spectrum and to analyse the sources of disturbances. The control and attenuation processes of the system were analysed in the frequency domain and the fluctuating perturbations caused by the pump were highlighted. © 2024 18th Conference of the International Society of Indoor Air Quality and Climate, INDOOR AIR 2024 - Conference Program and Proceedings. All rights reserved.

关键词： Air conditioning

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