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Effect of Fiber Reinforcement on Self-Healing Ability of Asphalt Mixture Induced by Microwave Heating

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SSRN 2022年

作者： Yang, Hanwen Ouyang, Jian Jiang, Zhao Ou, Jinping School of Civil Engineering Dalian University of Technology Dalian116024 China School of Transportation and Logistics Dalian University of Technology Dalian116024 China Key Lab of Structures Dynamic Behavior and Control The Ministry of Education China

Microwave heating is considered to be an effective method for accelerating the healing of the cracked asphalt mixture containing microwave-absorbing materials. However, the effects of fiber content and the microwave healing conditions on the selfhealing ability of fiber modified asphalt mixture are not clear. Moreover, the degree of freeze-thaw damage is a crucial aspect that might influence the self-healing ability and mechanical properties of the mixture. To obtain an asphalt mixture with both better selfhealing ability and mechanical properties, the healing index and the mechanical properties of fiber modified asphalt mixtures with three microwave-absorbing fibers additive (i.e. carbon fiber, steel fiber and steel wool) are studied by the semi-circular bending test in this paper. The results show that the freeze-thaw cycles have a great effect on self-healing ability and mechanical properties. However, the addition of fibers can improve the mechanical properties of asphalt mixtures under the initial state. Since the strength of steel fiber and steel wool cannot easily be affected by the action of bending and tensile load, the two fibers can provide better cohesive and adhesive strength with asphalt mastic in the fracture surface, attenuating the effect of freeze-thaw cycles on the self-healing ability of asphalt mixtures. Therefore, it is recommended that 3% of steel fiber and 4% of steel wool can be used as microwave-absorbing materials to enhance the self-healing ability of the asphalt mixtures. © 2022, The Authors. All rights reserved.

关键词： Microwaves

Evaluation on the Failure Modes and Progressive Collapse Resistance of Self-Centering Infilled Precast Concrete Frame

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SSRN 2023年

作者： Wang, Haoran Li, Shuang Zhai, Changhai Key Lab of Structures Dynamic Behavior and Control The Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

In this study, the refined finite element (FE) models for the collapse resistance of self-centering precast concrete (PC) frames with and without infill walls were established. Based on the validated FE models, the effects of different design parameters on the failure modes at the beam ends as well as the collapse resistance of the structures were carried out. Correspondingly, the reasonable optimization measures were suggested to reduce the concrete damage at the beam ends. The results indicated that the insufficient stirrup spacing may cause the concrete failed prematurely along the edge of the steel jackets due to stress concentration. Decreasing the thickness of steel angles could reduce the failure area of concrete at the beam ends, but also caused a significant reduction in the initial stiffness and vertical resistance of the structures. The thickness of steel jackets mainly influenced the size of failure area at the beam ends. The position of horizontal bolts and longitudinal bolts had effects on the failure modes of concrete at the beam ends as well as the collapse resistance of the structures, while the latter was particularly evident. Compared to the cast-in-place RC frames with the same size and reinforcement ratio, the damage extent at crucial locations of the optimized self-centering PC frame structures was lower, while exhibiting more excellent collapse resistance. A calculation model considering the resistance contribution of structural and non-structural infill wall members was proposed to predict the vertical resistance of self-centering PC frame structures in the compressive arch action (CAA) stage. © 2023, The Authors. All rights reserved.

关键词： Precast concrete

Preparation and Properties of a Cement-Based Permeable Crystalline Repair Material

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SSRN 2021年

作者： Lu, Rongwei Guan, Xinchun Zhang, Chenchen Kou, Yufeng Li, Jinglu Li, Yazhao Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China Harbin Institute of Technology Harbin150090 China

According to the performance requirements of concrete repair materials, a new cement-based permeable crystalline repair material（CCRM） was prepared, and its repair performance and repair mechanism were studied by means of macro mechanical property test, micro ESEM and XRD. The experimental results show that the prepared repair material not only has good flow performance and strength, but also enhances the strength of the repair interface, so that the repair interface is no longer the weak point of the repaired specimen. Through the observation of the microstructure of the repaired specimen, it is found that CCRM can penetrate into the interface of the repaired specimen to form a cross transition zone, and then form a better integration with the repaired specimen, with very good compatibility. Through the test of CCRM repair products by XRD and TG, it is found that there is an active component in CCRM, which can consume calcium hydroxide to form a complex, promote the transformation of calcium carbonate and C-S-H, and then enhance the repair effect. © 2021, The Authors. All rights reserved.

关键词： Repair

Identification of Chloride Diffusion Coefficient in Concrete Using Physics-Informed Neural Networks

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SSRN 2023年

作者： Wan, Yutong Zheng, Wenzhong Wang, Ying Key Lab of Structures Dynamic Behavior and Control The Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

The corrosion of steel caused by chloride is one of the important causes of the deterioration of reinforced concrete structures. In order to describe the transport behavior of chlorides in concrete and to make quantitative durability designs based on it, it is necessary to determine the chloride diffusion coefficient correctly. However, the commonly used analytical method is not suitable for the free chloride diffusion coefficient considering the nonlinear chloride binding capacity of concrete. In this study, by comparing the results of solving forward problems involving chloride transport equations using finite element method (FEM) and solving corresponding inverse problems using physics-informed neural networks (PINNs), it is verified that PINNs can be applied to identify the chloride diffusion coefficient in non-steady-state immersion tests and accelerated chloride migration tests considering no chloride binding, Langmuir binding, or Freundlich binding. The robustness of PINNs is verified by training with 5% noise data as observed data. The results of interpolation and extrapolation using PINNs trained successfully show its excellent generalization performance. © 2023, The Authors. All rights reserved.

关键词： Diffusion

Mussel-Inspired Modified Tannic Acid Additive To Strengthen Interfacial Bonds Of Epoxy Resin With Steel Substrates

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Mussel-Inspired Modified Tannic Acid Additive To Strengthen ...

第八届中国国际粘接技术大会

作者： Noel Babu Guijun Xian Key Lab of Structures Dynamic Behavior and Control Ministry of EducationHarbin Institute of Technology Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology School of Civil Engineering Harbin Institute of Technology

Epoxies are widely used as coatings and adhesives in many structural ***,the loss of interfacial adhesion between the resin and substrate is a concern,especially in moist *** recent years,much attention has been directed toward mimicking the adhesion mechanism utilised by mussels to holdfast themselves onto underwater *** an inexpensive solution that can be quickly adopted for large-scale industrial applications is yet to be *** acid(TA) is a readily availab.e polyphenol from plants with abundant phenolic hydroxyl *** was found that chemical modification of TA was necessary to use its phenolic –OH groups to mimic mussel *** was grafted with hydrophobic chains of allyl glycidyl ether(AGE) in the presence of a base *** 1wt.% additive in the resin(TA-AGE1),a 37% increase in shear strength was obtained with steel *** Boeing wedge test was performed in a harsh environment(water bath at 60 ℃) to confirm the interfacial bond *** is proposed that with the incorporation of the additive,more hydrogen and coordination bonds can be formed at the resin-adherend interface contributing to the strengthening of interfacial bonds.

关键词： Epoxy resin Mussel adhesion Tannic acid Interfacial bond durability

Experimental Study of the Wake of Multi-Rotor Turbine

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SSRN 2022年

作者： Xiong, Xue-Lu Laima, Shujin Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin150090 China

This paper describes a comparative experimental study of the wake of a multi-rotor turbine and a single-rotor turbine. The wake merge process in the multi-rotor wake is analyzed from various perspectives. A jet-like gap flow region and a momentum redistribution region are found in the region before and after the full merge of the individual rotor wakes, respectively. Compared to the single-rotor wake, the fully merged multi-rotor wake is found to have a slower recovery rate and a lower turbulent kinetic energy. Furthermore, two sources are found for the peak frequency in the multi-rotor wake which results in different peak frequencies at different locations. One of the two sources is the rotor wake meandering with the meandering frequency maintain the same throughout the wake, and another one corresponds to the dynamic of the shear layer in the gap region with its peak frequency decrease in the streamwise direction. The yawed multi-rotor wake is found to be similar to the non-yawed case except for the wake deflection of the yawed case. And the deflection is more pronounced in the yawed multi-rotor wake than in the yawed single-rotor wake which indicates a higher yaw efficiency for the multi-rotor turbine. © 2022, The Authors. All rights reserved.

关键词： Wakes

Pseudodynamic tests with substructuring of a full-scale precast box-modularized structure made of reinforced concrete shear walls

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Pseudodynamic tests with substructuring of a full-scale prec...

作者： Xu, Guoshan Wang, Zhen Wu, Bin Bursi, Oreste S. Tan, Xiaojing Yang, Qingbo Wen, Long Jiang, Hongbin Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin China School of Civil Engineering Harbin Institute of Technology Harbin China Department of Civil Environment & Mechanical Engineering University of Trento-Italy Trento Italy Yunnan Institute of Building Research Kunming China Jiangsu Power Design Institute Co. Ltd. of China Energy Engineering Group Nanjing China

A novel horizontal and vertical wall-to-wall and wall-to-floor connection methods for precast box-modularized structure with reinforced concrete shear walls (PBSRCSWs) are proposed in this paper. The entailing behavior of the proposed connections and the seismic performance of one full-scale six-story PBSRCSWs were experimentally studied by means of pseudodynamic substructure tests. In order to improve the relevant experimental accuracy, we presented and validated one versatile testing platform Hytest, combined with external displacement feedback control (EDFC;Hytest with EDFC). In greater detail, it was shown from the pseudodynamic substructure test results that the proposed Hytest with EDFC can effectively impose the desired displacements on the specimens rather than on the actuators. Moreover, both the horizontal and vertical wall-to-wall connections proposed for the PBSRCSWs exhibited a favorable behavior whilst the PBSRCSWs subjected to earthquake records showed an excellent seismic performance. Copyright © 2017 John Wiley & Sons, Ltd.

关键词： Feedback control

Analysis on dynamic response of reinforced reactive powder concrete two-way slab. under blast load

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Jianzhu Jiegou Xuebao/Journal of Building structures 2014年 35卷 91-98页

作者： Hou, Xiaomeng Li, Gang Zheng, Wenzhong Key Lab of Structures Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China

Reactive powder concrete (RPC) is a kind of new cementitious composite material with super high performance and high toughness, which has extensive application prospect in protective engineering. The dynamic response of RPC slab. is the basis of design of structures to resist blast. Based on compressive and tensile split Hopkinson pressure bar test results, empirical relations of dynamic increase factor (DIF)-strain rate for RPC were obtained. An approach for modeling reinforced RPC slab. under blast is presented using the software LS-DYNA. The validity of the model was established by comparing predictions from numerical analysis with relating test results. Results from parametric studies indicate that dynamic displacement of slab. is reduced significantly by considering the strain rate effect. The dynamic displacement of slab. is decreased by increasing scaled distance of blast load, depth of slab., compressing strength of PRC and reinforcement ratio of slab.. Boundary conditions and depth of slab. have significant influence on dynamic response of RPC slab., while load level and reinforcement ratio have minor influence on dynamic response of RPC slab.. It is an effective method to increase the depth of slab. and restraint effects to improve the blast-resistant of slab.. ©, 2014, Science Press. All right reserved.

关键词： dynamic response

Stability Analysis and Design Methods of Steel Pipe Piles in Extreme Marine Corrosive Environments

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SSRN 2023年

作者： Han, Xinhao Liu, Changyong Hu, Qing Su, Andi Zhang, Sumei Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

Steel pipe piles (SPPs) are commonly applied for marine platform foundations due to high bearing capacity. However, for SPPs in corrosive marine environments, the corrosion on the steel tube is severe and shows a non-uniform distribution along the height direction, resulting in the significant decrease of the stability bearing capacity. To investigate the stability performance of SPPs in marine corrosive environments, the corroded SPPs are simplified into five-segment stepped columns, and the equilibrium differential equations are established to obtain the rotational stiffness relationship. The accurate solutions of the critical buckling loads of five-segment stepped columns under arbitrary boundary conditions are obtained by iterative methods. Besides, considering the material and geometrical nonlinearity, the finite element (FE) model of corroded SPPs is established and then verified based on existing test results. The effects of the number of segments and stiffness ratios among different segments on the bearing capacity are analysed. Furthermore, considering the interactions among different segments, the calculation methods for the stability bearing capacity of stepped columns under axial compression and combined compression-bending are proposed respectively. The comparison between calculated and FE results indicates that the proposed calculation methods have good prediction accuracy and can be availab.e for practical engineering reference. © 2023, The Authors. All rights reserved.

关键词： Bearing capacity