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Chemically bonded multi-nanolayer inorganic aerogel with a record-low thermal conductivity in a vacuum

National Science Review 2023年第10期10卷 96-105页

作者： Hongxuan Yu Menglin Li Yuanpeng Deng Shubin Fu Jingran Guo Han Zhao Jianing Zhang Shixuan Dang Pengyu Zhang Jian Zhou Dizhou Liu Duola Wang Chuanwei Zhang Menglong Hao Xiang Xu Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology and Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast University Key Lab of Aerospace Bearing Technology and Equipment of the Ministry of Industry and Information Technology Harbin Institute of Technology

Inorganic aerogels have exhibited many superior characteristics with extensive applications,but are still plagued by a nearly century-old tradeoff between their mechanical and thermal *** reducing thermal conductivity by ultralow density,inorganic aerogels generally suffer from large fragility due to their brittle nature or weak joint crosslinking,while enhancing the mechanical robustness by material design and structural engineering,they easily sacrifice thermal insulation and ***,we report a chemically bonded multi-nanolayer design and synthesis of a graphene/amorphous boron nitride aerogel to address this typical tradeoff to further enhance mechanical and thermal *** to the chemically bonded interface and coupled toughening effect,our aerogels display a low density of 0.8 mg cm-3with ultrahigh flexibility（elastic compressive strain up to 99% and bending strain up to 90%）,and exceptional thermostability（strength degradation <3% after sharp thermal shocks）,as well as the lowest thermal conductivities in a vacuum(only 1.57 mW m-1K-1at room temperature and 10.39 mW m-1K-1at500℃) among solid materials to *** unique combination of mechanical and thermal properties offers an attractive material system for thermal superinsulation at extreme conditions.

关键词： inorganic aerogels multi-nanolayer mechanical-thermal tradeoff flexibility thermal superinsulation

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Study on the effect of ground motion direction on the response of engineering structure

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Earthquake Engineering and Engineering Vibration 2016年第4期15卷 649-656页

作者： Sun Menghan Fan Feng Sun Baitao Zhi Xudong Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology School of Civil Engineering Harbin Institute of Technology Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration

Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on a structure are studied herein. Ground motion records usually contain three vertical ground motion data, which are obtained by sensors arranged in accordance with the EW （East -West） direction, NS （South- North） direction and perpendicular to the surface （z） direction, referring to the construction standard of seismic stations. The seismic records in the EW and NS directions are converted to Cartesian coordinates in accordance with the rotation of θ = 0°-180°, and consequently, a countless group of new ground motion time histories are obtained. Then, the characteristics of the ground motion time history and response spectrum of each group were studied, resulting in the following observations：（1） the peak and phase of ground motion are changed with the rotation of direction θ, so that the direction θ of the maximum peak ground motion can be determined; （2） response spectrum values of each group of ground motions change along with the direction θ, and their peak, predominant period and declining curve are also different as the changes occur; then, the angle θ in the direction of the maximum peak value or the widest predominant period can be determined; and （3） the seismic response of structures with different directions of ground motion inputs has been analyzed under the same earthquake record, and the results show the difference. For some ground motion records, such as the Taft seismic wave, these differences are significant. Next, the Lushan middle school gymnasium structure was analyzed and the calculation was checked using the proposed method, where the internal force of the upper space truss varied from 25% to 28%. The research results presented herein can be used for reference in choosing the ground motion when checking the actual damage to struct

关键词： direction of grotmd motion structure effect coordinate transformation response spectrum

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Experimental validation of a signal-based approach for structural earthquake damage detection using fractal dimension of time frequency feature

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Earthquake Engineering and Engineering Vibration 2014年第4期13卷 671-680页

作者： Tao Dongwang Mao Chenxi Zhang Dongyu Li Hui Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration Key Lab of Structures Dynamic Behavior and Control (Harbin Institute of Technology) Ministry of Education Center of Structural Monitoring and Control School of Civil Engineeing Harbin Institute of Technology

This article extends a signal-based approach formerly proposed by the authors, which utilizes the fractal dimension of time frequency feature （FDTFF） of displacements, for earthquake damage detection of moment resist frame （MRF）, and validates the approach with shaking table tests. The time frequency feature （TFF） of the relative displacement at measured story is defined as the real part of the coefficients of the analytical wavelet transform. The fractal dimension （FD） is to quantify the TFF within the fundamental frequency band using box counting method. It is verified that the FDTFFs at all stories of the linear MRF are identical with the help of static condensation method and modal superposition principle, while the FDTFFs at the stories with localized nonlinearities due to damage will be different from those at the stories without nonlinearities using the reverse-path methodology. By comparing the FDTFFs of displacements at measured stories in a structure, the damage-induced nonlinearity of the structure under strong ground motion can be detected and localized. Finally shaking table experiments on a 1：8 scale sixteen-story three-bay steel MRF with added frictional dampers, which generate local nonlinearities, are conducted to validate the approach.

关键词： earthquake damage detection time frequency feature fractal dimension signal-based shaking table test frictional damper

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Time-dependent reliability prediction analysis of bridge members considering dependence of failure modes and proof modes

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key Engineering Materials 2015年 648卷 25-34页

作者： Liu, Yuefei Lu, Dagang Key Laboratory of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin China School of Civil Engineering Harbin Institute of Technology Harbin China

Structural health monitoring systems used in bridges contain sensors providing a large amount of monitored data, such as stress, deflection and ***. In this paper, firstly, based on monitored everyday extreme stress data, time-variant proof load effects of structural members were defined, and based on the time-dependent proof load effects, the time-dependent performance functions of structural member's proof modes were built;and then based on the monitored data, the Bayesian dynamic models(BDMs) of extreme stresses were built, and based on the predicted extreme stress with BDMs, the time-variant performance functions of structural member's failure modes were given;and then based on the time-dependent performance functions of failure modes and proof modes and correlation coefficients between them, with the conditional probability method, the time-dependent reliability indices of structural members were updated and predicted;finally an actual engineering was provided to illustrate the application of the proposed models and methods. © 2015 Trans Tech Publications, Switzerland.

关键词： dynamic models

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Long-term performance of steel-recycled aggregate concrete continuous composite beams considering the influence of installing decorative layers

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Engineering structures 2025年 339卷

作者： Xuepeng Chen Huan Zhang Yu-Yin Wang Hongzhe Dai Lilong Fan Yue Geng Key Lab of Structures Dynamic Behaviour and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China China Railway Construction Bridge Engineering Bureau Group Co. Ltd. Tianjin 300000 China State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Nanning Guangxi 530004 China

Steel-recycled aggregate concrete composite beams (SRACCBs) are preferred components for the recycled aggregate concrete (RAC) application. Due to their superior spanning ability and load-bearing capacity, steel-concrete composite beams (SCCBs) are typically more slender than traditional beam components, which makes them more sensitive to concrete shrinkage and creep. Furthermore, the incorporation of recycled aggregate (RA) significantly increases the shrinkage and creep deformation of the concrete. Therefore, the long-term properties of RAC significantly affect the application of SRACCBs. In fact, the shrinkage and creep of RAC are closely related to the boundary conditions, and the sealing effect of the steel deck and decorative layer can directly influence the long-term deformation of SCCBs. However, relevant research is currently unavailable. In this context, a 500-day long-term performance test of continuous SRACCB (4 m × 2 spans) was conducted in this paper. The test quantified the effects of incorporating RA and installing decorative layers on the mid-span deflection and end relative slip of the SRACCBs. By considering the cracking, shrinkage, and creep of RAC and long-term slip at the interface, a Direct Stiffness Method Finite Element Model (DSMFEM) for SRACCBs was established. Test results indicate that using 100 % RA can increase the mid-span deflection of the specimen by 27.9 % and the relative slip by 54.8 %; a 90-day installation of the decoration layer can lead to a 16.3 % decrease in the mid-span deflection and an 11.5 % decrease in the relative slip. The verification results of 12 sets of experimental data indicate that the proposed DSMFEM has high computational efficiency and can effectively predict the deflection and relative slip of simply-supported and continuous SCCBs. The maximum error in predicting the final mid-span deflection is 6.8 % for specimens with long-term loads and 18.4 % for specimens without loads.

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Predicting the capacity of perfobond rib shear connector using an ANN model and GSA method

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Frontiers of Structural and Civil Engineering 2022年第10期16卷 1233-1248页

作者： Guorui SUN Jun SHI Yuang DENG School of Civil Engineering Central South UniversityChangsha 410075China Key Laboratory of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090China National Engineering Laboratory for High-Speed Railway Construction Changsha 410075China

Due to recent advances in the field of artificial neural networks(ANN)and the global sensitivity analysis(GSA)method,the application of these techniques in structural analysis has become feasible.A connector is an important part of a composite beam,and its shear strength can have a significant impact on structural *** this paper,the shear performance of perfobond rib shear connectors(PRSCs)is predicted based on the back propagation(BP)ANN model,the Genetic Algorithm(GA)method and GSA method.A database was created using push-out test test and related references,where the input variables were based on different empirical formulas and the output variables were the corresponding shear *** results predicted by the ANN models and empirical equations were compared,and the factors affecting shear strength were examined by the GSA *** results show that the use of ANN model optimization by GA method has fewer errors compared to the empirical ***,penetrating reinforcement has the greatest sensitivity to shear performance,while the bonding force between steel plate and concrete has the least sensitivity to shear strength.

关键词： perfobond rib shear connector shear strength ANN model global sensitivity analysis

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Analysis of micro-disturbance drilling pipe pre-reinforcement method for deep excavations above operating subway tunnels

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Frontiers of Structural and Civil Engineering 2025年

作者： Tang, Wenchong Kong, Xiangxun Tang, Liang Ling, Xianzhang School of Civil Engineering Harbin Institute of Technology Harbin150090 China Chongqing Research Institute Harbin Institute of Technology Chongqing401135 China Key Laboratory of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China

This paper uses the three-dimensional numerical simulation method to analyze the first deep foundation pit project directly above the operating subway in a certain area. The monitoring data were compared with the numerical results to verify the accuracy of the numerical model, and then a series of analyses were performed. The soil beneath the tunnel is the most direct object of tunnel deformation caused by the excavation of deep foundation pits above the tunnel. The rebound deformation of the soil beneath the tunnel forces the tunnel to produce an upward deformation cooperatively. Therefore, after comparing and analyzing the prevention criteria of traditional excavation measures, which were not sufficient for this project, a new method of fortification is proposed for the foundation pit above the tunnel, which is called the micro-disturbance drill pipe pre-reinforcement method (PRM) for the soil beneath the tunnel. The comprehensive parameter analysis of the PRM shows that the PRM can effectively reduce the uplift value of the tunnel, and the reinforcement effect is obvious. © Higher education Press 2025.

关键词： Tunneling (excavation)

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CFD investigations into snow loads on tandem-arranged gabled-roofed buildings under mutual interferences

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Cold Regions Science and Technology 2025年 238卷

作者： Zhang, Guolong Zhang, Qingwen Mo, Huamei Guo, Dong Zhi, Xudong Wu, Jinzhi Fan, Feng Key Laboratory of Structures Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China Key Laboratory of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China Company Limited Macau999078 China Faculty of Architecture Civil and Transportation Engineering Beijing University of Technology Beijing100124 China Key Laboratory of Urban Security and Disaster Engineering Ministry of Education Beijing University of Technology Beijing100124 China

Gable-roofed buildings arranged in tandem layouts are prevalent in various industrial factories and warehouses. However, during extreme blizzards, these snow-sensitive roof structures frequently sustain significant damages due to mutual interferences between adjacent buildings. Regrettably, the snow load calculation methods provided by various national load codes primarily depend on the studies of snowdrifts on multiple flat roofs in built-up environments, overlooking the impact of other roof shapes on the interference effects. Therefore, this study delves into the snow loads on tandem-arranged gable-roofed buildings with diverse layouts under mutual interferences. Initially, a wind tunnel test of snowdrifts on a gable roof was carried out to validate the numerical method adopted in this study. Subsequently, a series of pre-simulations were performed to identify the key parameters essential for analyzing the interference effects. On the basis, an extensive study was carried out to investigate the interference mechanisms and snowdrift characteristics on two tandem-arranged gable roofs with different layouts. Overall, the interference effect manifests solely as the redistribution of snow on downstream gable roofs, categorizable into the sheltering effect in the downwind direction and the disturbance effect in the crosswind direction. The disturbed snow load on the downstream gable roof exhibits an overall uniform distribution pattern controlled by the sheltering effect, but locally shows erosion due to the disturbance effect. Across various building layouts, the snow loads on disturbed gable roofs display a strong linear trend with the spacing. Consequently, a calculation method for snow loads on disturbed gable roofs was finally proposed, comprehensively considering the interference effects of height differences and spacings. © 2025

关键词： Tall buildings

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Longitudinal shear behavior of composite slabs with recycled coarse and fine aggregate concrete

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Case Studies in Construction Materials 2025年 22卷

作者： Jiongzhuo Bai Yue Geng Yu-Yin Wang Charles K.S. Moy Huan Zhang School of Civil Engineering Harbin Institute of Technology Harbin Heilongjiang 150090 China Key Lab of Structures Dynamic Behaviour and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China Guangdong Provincial Key Laboratory of Modern Civil Engineering Technology Guangzhou 510641 China State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Nanning Guangxi 530004 China Department of Civil Engineering Xi’an Jiaotong-Liverpool University Suzhou 215123 China

Steel-concrete composite slabs, as efficient modern structural components, can incorporate coarse recycled aggregates (CRA) and fine recycled aggregates (FRA) as green alternatives to sand and gravel. However, existing studies have not sufficiently investigated the effects of recycled coarse and fine aggregates as well as loading history on the longitudinal shear capacity of composite slabs, and the applicability of current design methods specified in existing codes for recycled aggregate concrete (RAC) composite slabs has yet to be systematically validated. Therefore, this study systematically investigates recycled aggregates (RAs) composite slabs through experimental testing and numerical modeling. Three full-scale specimens with closed steel decking were tested under varying RAs replacement ratios (coarse/fine aggregates) and sustained load durations (0–500 days). A validated finite element (FE) model incorporating interfacial bond-slip behavior was developed, enabling 136 parametric simulations to assess m-k and partial shear connection ( PSC ) approaches following Eurocode 4. The results show: (1) RAs incorporation reduces initial stiffness and cracking load by 14.3 % and 27.1 %, respectively, but negligibly affects ultimate shear capacity; (2) 500-day sustained loading enhances shear capacity, stiffness, and cracking load by 9.3 %, 26.3 %, and 16.1 % through concrete aging; (3) Both Eurocode 4 methods demonstrate satisfactory applicability for RAs composite slab design. These results provide critical validation for sustainable composite slab engineering using recycled materials.

关键词： Steel-concrete composite slab Recycled aggregate Loading history Longitudinal shear Bearing capacity

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Improvement of sludge dewaterability with modified cinder via affecting EPS

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Frontiers of Environmental Science & Engineering 2017年第6期11卷 179-192页

作者： Weichao Ma Lei Zhao Huiling Liu Qianliang Liu Jun Ma State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology Harbin 150090 China School of Architectural Engineering Heilongiiang University Harbin 150080 China Key Laboratory of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China Key Laboratory of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China

The relationship between the improvement of sludge dewaterability and variation of organic matters has been studied in the process of sludge pre-conditioning with modified cinder, especially for extracellular polymeric substances （EPS） in the sludge. During the conditioning process, the decreases of total organic carbon （TOC） and soluble chemical oxygen demand （SCOD） were obviously in the supernatant especially for the acid modified cinder （ACMC）, which could be attributed to the processes of adsorption and sweeping. The reduction of polysaccharide and protein in supernatant indicated that ACMC might adsorb EPS so that the tightly bound EPS （TB-EPS） decreased in sludge. In the case of ACMC addition with 24 g·L^-1, SRF of the sludge decreased from 7.85 × 10^12 m·kg^-1 to 2.06× 10^12 m·kg^-1, and the filter cake moisture decreased from 85% to 60%. The reconstruction of ＂floc mass＂ was confirmed as the main sludge conditioning mechanism. ACMC promoted the dewatering performance through the charge neutralization and adsorption bridging with the negative EPS, and provided firm and dense structure for sludge floc as skeleton builder. The passages for water quick transmitting were built to avoid collapsing during the high-pressure process.

关键词： Sludge conditioning Acid or alkali modified cinder TB-EPS Floc mass Floc reconstruction

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