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Mechanical properties of extrusion-based 3D-printed concrete considering the thickness of the printed layer and printing time interval

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structures 2025年 78卷

作者： Tang, Boyang Yan, Jiachuan Han, Xiaoyu Lin, Yini Fan, Feng 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 School of Civil Engineering Harbin Institute of Technology Harbin150090 China

This paper investigated the performance of 3D printed concrete with a focus on the bonding layer, considering the thickness of the printed layers. Through experimental testing and numerical simulation, the mechanical properties and failure mechanisms of the bonding layer were thoroughly analyzed. The results revealed that compressive strength diminishes with thinner layers and longer printing intervals, while anisotropic mechanical properties become increasingly pronounced with reduced layer thickness. The static performance of 3D printed concrete arches was also studied, showing that increased layer thickness enhances the ultimate load bearing capacity. Cohesive elements were used to simulate compressive strength across varying layer thicknesses and printing time intervals. Prediction formulae for compressive strength were developed and validated through experimental data. The study further simulated the static performance of arches using both cohesive elements and anisotropic material properties, confirming the accuracy of the strength prediction formulae and the effectiveness of the simulation methods. © 2025

关键词： Compressive strength

Seismic performance of buckling-restrained braced steel frames subjected to earthquake main shock-aftershock sequences

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Seismic performance of buckling-restrained braced steel fram...

2022 International Conference on Applied Mechanics and Advanced Materials, ICAMAM 2022

作者： Gong, Chao Jia, MingMing Cheng, XuanHao Gritcuk, Mishel China Metallurgical Construction Research Institute Co. Ltd. Beijing100088 China 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 School Of Civil Engineering Harbin Institute Of Technology Harbin150090 China

Recently, there are many papers report the development of some new buckling-restrained braced (BRB) frames and the evaluation of its characteristics. At the same time self-centering buckling-restrained braced (SCBRB) frames are considered as new solutions for the increasing of the structural resilience. In this thesis, the seismic performance of structures is analyzed subjected to earthquake main shock-aftershock sequences. There is comparison of two types of the additional BRB elements, and also there is comparison between them and original steel frame to show the effect of using BRB and SCBRB elements. To compare the seismic performance of BRBF and SCBRBF, the same main shock-aftershock sequences were used in this part. Because of the flag-shaped hysteretic curve of the SCBRB elements, big amount of the energy was dissipated during the motion. Compared to steel frame, smaller seismic responses and residual deformation occurred the structure. BRBF and SCBRBF can control the seismic responses effectively due to the energy dissipation of BRB, and SCBRB can also reduce the structural residual deformation. The earthquake aftershock after earthquake main shock can increase the structural damage and enlarge the structural seismic responses. © Published under licence by IOP Publishing Ltd.

关键词： Seismic response

Landslide intrusion monitoring method based on ?-OTDR 8

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Landslide intrusion monitoring method based on ?-OTDR

8th Symposium on Novel Photoelectronic Detection Technology and Applications

ISBN: (纸本)9781510653115

Phase-sensitive optical time domain reflectometry (?-OTDR) technology is a disturbance monitoring technology based on Rayleigh scattering. The principle is that when sensing fiber is disturbed, the refractive index at the disturbance point will change, which will affect the intensity of Rayleigh backscattered light, so as to locate disturbance point. This technology can be used for perimeter security, intrusion monitoring etc. For a landslide about to slide, timely and accurate detection of intrusion events on it is of great significance for the evaluation of landslide state and timely response. In this paper, we proposed a method for landslide intrusion monitoring based on ?-OTDR. We first studied the performance of the instrument used in this work. Then, different intrusion behaviors were simulated and monitored. And the signal characteristics of different behaviors were analyzed. Test results show that different intrusion events can be distinguished by event frequency. © 2022 SPIE

关键词： Landslides

Simulation of thermal radiation effects on the thermal properties of parietodynamic walls using an innovative model

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Low-carbon Materials and Green Construction 2024年第1期2卷 279-296页

作者： Xianzhang Dong Baochen Lin Huigang Xiao Min Liu School of Civil Engineering Harbin Institute of Technology73 Huanghe RoadHarbinHeilongjiang 150090People’s Republic of China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090People’s Republic of China Heilongjiang Heijianyi Construction Engineering Co. Ltd.Harbin 150040People’s Republic of China

The parietodynamic wall, a type of dynamic insulation, has been recognized as an effective technology to reduce energy loss in buildings by recovering heat energy through forced convection. However, current research on the thermal performance of parietodynamic walls has overlooked the influence of thermal radiation, a crucial factor in energy transfer within the air layers of these walls. To bridge this gap, an innovative simulation model was developed and experimentally validated. Employing simulation methods, we investigated the impact of thermal radiation on the thermal behavior of parietodynamic walls under various influencing factors. Our findings reveal that thermal radiation markedly increases heat loss. Specifically, at an emissivity of 1, thermal radiation contributes up to 80.7% to the heat transfer coefficient (HTC) of the parietodynamic wall. Moreover, for a parietodynamic wall without insulation, the HTC of this wall will increase by more than 268% when thermal radiation is taken into account, compared to when it is not considered. These revelations deepen our comprehension of the role of thermal radiation in parietodynamic walls and offer valuable guidance for the development of more energy-efficient buildings.

关键词： Parietodynamic wall Thermal performance Thermal radiation Air layer Heat recovery Simulation

Experimental and Analytical Investigations on Impact Responses of Scs Panel with Dual Energy Absorbers

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SSRN 2024年

作者： Lu, Jingyi Wang, Yonghui Zhou, Hongyuan Ma, Jialu 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 Key Lab of Urban Security and Disaster Engineering The Ministry of Education Beijing University of Technology Beijing100124 China Institute of Engineering Mechanics China Earthquake Administration Harbin150080 China

A new steel-concrete-steel panel with front aluminum foam layer and rear energy absorbing connector (SCS-FL-EAC) was firstly developed. The dynamic behavior of SCS-FL-EAC was studied through conducting drop-weight impact tests. Three stages of impact process of SCS-FL-EAC were identified. The aluminum foam layer and energy absorbing connector were crushed under impact loading. The aluminum foam layer reached densification, and a local indention was observed beneath the projectile. Plastic hinges were also found at the corners of the pleated steel plate of the energy absorbing connector. The SCS panel exhibited the combination of bi-linear global flexural deformation and local deformation. Furthermore, the effects of aluminum foam layer on the impact resistant performances of SCS-FL-EAC were investigated. The results indicated that the inclusion of the aluminum foam layer effectively mitigated inertial effects and reduced the maximum impact force. Additionally, the SCS-FL-EAC demonstrated improved impact-resistant performances with an increased thickness of the aluminum foam layer. Furthermore, an analytical model was proposed to predict the force and displacement responses of SCS-FL-EAC subjected to impact load, and the predicted impact responses showed good agreement with experimental results. © 2024, The Authors. All rights reserved.

关键词： Energy absorption

Convective meta-thermal concentration for ultrahigh efficient Stirling engine with waste heat and cold utilization

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arXiv

arXiv 2023年

作者： Zhou, Xinchen Xu, Xiang Ouyang, Xiaoping Huang, Jiping Fudan University Shanghai200433 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters the Ministry of Industry and Information Technology Key Lab of Structures Dynamic Behavior and Control the Ministry of Education Harbin Institute of Technology Harbin150090 China School of Materials Science and Engineering Xiangtan University Xiangtan411105 China

The Stirling engine, which possesses external combustion characteristics, a simple structure, and high theoretical thermal efficiency, has excellent potential for utilizing finite waste heat and cold resources. However, practical applications of this technology suffered from thermal inefficiency due to the discontinuity and instability of waste resources. Despite advances in energy storage technology, temperature variations in the heat-exchanging fluids at the hot and cold ends of the Stirling engine remained significant obstacles. In this work, convective meta-thermal concentration (CMTC) was introduced between the heating (cooling) fluids and the hot (cold) end of the Stirling engine, employing alternating isotropic materials with high and low thermal conductivities. It was demonstrated that CMTC effectively enhanced the temperature difference between the hot and cold ends, leading to a remarkable improvement in Stirling engine efficiency. Particularly, when the Stirling engine efficiency tended to zero due to the limited availability of waste heat and cold resources, CMTC overcame this limitation, surpassing existing optimization technology. Further analysis under various operating conditions showed that CMTC achieved a significant thermal efficiency improvement of up to 1460%. This work expanded the application of thermal metamaterials to heat engine systems, offering an exciting avenue for sustainable energy utilization. Copyright © 2023, The Authors. All rights reserved.

关键词： Waste heat

Effect of Thermal Radiation on the Thermal Properties of Parietodynamic Walls

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SSRN 2023年

作者： Dong, Xianzhang Lin, Baochen Xiao, Huigang Liu, Min School of Civil Engineering Harbin Institute of Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin150090 China Heilongjiang Heijianyi Construction Engineering Co. Ltd 150040 China

The parietodynamic wall, a type of dynamic insulation, has been identified as an effective technology to reduce energy loss in buildings by recovering heat and cold energy through forced convection. However, current research on the thermal performance of parietodynamic walls has neglected the influence of thermal radiation, a crucial factor in energy transfer within the air layer of the wall. To address this gap, a numerical model that couples thermal radiation, heat transfer in solids and fluids, and turbulence is established to evaluate the effect of thermal radiation. Our results indicate that emissivity, the thermal resistance of the insulation layer, and air layer thickness significantly affect the proportion of thermal radiation in heat transfer. Specifically, when the emissivity is 1, the contribution ratio of thermal radiation to the heat transfer coefficient (HTC) of the parietodynamic wall is by up to 80.7%. Moreover, low thermal resistance of the insulation layer can increase the HTC by 268%-630% through thermal radiation gain. These findings improve our understanding of the effect of thermal radiation in parietodynamic walls, which would aid in the development of more energy-efficient buildings. © 2023, The Authors. All rights reserved.

关键词： Heat radiation

Experimental Study on Flexural Performance of Ultra-High-Performance Concrete with Recycled Aggregate Co-Modified by Nano-Silica and Steel Fiber

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SSRN 2023年

作者： Luo, Liang Shi, Jun Wang, Jianan Qu, Yiwen Dai, Bin School of Civil Engineering Central South University Changsha410075 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

Expanding the application of defective recycled aggregates (RA) to ultra-high performance concrete (UHPC), it is necessary to modify them with nano-silica (NS) in conjunction with steel fibers (SF), and it is worthwhile to investigate the bending behavior under the typical characteristics of this new *** study investigates the flexural performance of recycled aggregate ultra-high-performance concrete (RA-UHPC) using a four-point bending test and analyzes the influence of RA substitution rates (0%, 50%, and 100%), SF content (0%, 1%, and 2%), and NS content (0%, 1%, 3%, and 5%) on its flexural toughness and microstructure. Additionally, digital image correlation (DIC) technology was employed to capture crack evolution during the test, and SEM microstructural analysis was used to elucidate the flexural mechanism of this fiber-nano composite concrete. The results show that the load-deflection curves of specimens without SF exhibit initial linear-elastic growth, followed by a sharp decrease in load after the peak without a distinct descending stage. In contrast, specimens with SF display three typical stages, with a smoother and flatter descending stage. The cross-distributed SF enhances post-peak ductility, transforming the failure behavior from quasi-brittle to ductile. Increasing SF content significantly enhances the flexural strength and toughness of the specimens, while an increase in RA substitution rate and NS content results in a slight reduction in flexural strength (fp). The changes in residual strength observed through both methods are consistent, with almost no residual strength in the brittle failure specimens. Moreover, DIC technology, relying on precise image capture, can predict crack positions before the peak load is reached. Finally, the microstructural analysis in SEM is combined to illustrate the flexural mechanism of this fiber-nanocomposite concrete. © 2023, The Authors. All rights reserved.

关键词： Image correlation

Experimental and Numerical Studies of Compressive Strength of 3d Printed Concrete Considering Interlayer Bonding Performance

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SSRN 2023年

作者： Tang, Boyang Yan, Jiachuan Han, Xiaoyu Lin, Yini Fan, Feng 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 the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

This paper studied the compressive properties of 3D printed concrete and analyzed their influencing factors, including layer thickness and printing time interval. The investigation also explored the impact of inter-layer and inter-bar bonding properties on concrete's compressive strength by examining key factors. The findings revealed that compressive strength decreases as layer thickness decreases and printing time interval increases. Moreover, interlayer tensile and shear strength decrease with longer printing time intervals, while the anisotropic mechanical properties of 3D printed concrete become more pronounced as the number of printed layers increases. The study employed cohesive elements to numerically simulate the compressive strength of concrete specimens with varying number of layers and interlayer intervals. Parametric analysis was conducted to investigate bonding layer failure under different loading directions, and damage modes were analyzed. Finally, an empirical equation for predicting the compressive strength of 3D printed concrete was proposed and validated using experimental data. © 2023, The Authors. All rights reserved.

关键词： Compressive strength