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How to design energy-efficient building materials, theoretically requiring a balance of mechanical properties and thermal conductivity, remains a crucial challenge in construction & building fields. Recently there is an increased interest in using 3D concrete printing technology to automatically manufacture complicated and customized constructions. Nevertheless, majority of printed constructions are still solid and have a low quality in the interface performance. Inspired by the lightweight lattice architecture, 3D core-framework lattice cementitious composites (CS-LCCs) is proposed in this work, which consists of printed polymeric framework and cement mortar. Results show that although the average compressive strength of CS-LCCs is lower than that of the cubic sample fabricated using the cement mortar (40 × 40 × 40 mm3), the specific strength of CS-LCCs approaches that of cubic one. The ductility of CS-LCCs is obviously improved due to the effect of polymeric framework. According to the test and finite element analysis, a hinging and stretching couple deformation mechanism is used to elaborate the deformation mechanism of CS-LCCs. Additionally, the CS-LCCs also exhibit low thermal conductivities at various temperatures owing to the ordered porous characteristic of lattice.
Jian Song; Mengqin Cao; Lianmin Cai; Yizhou Zhou; Junying Chen; Su Liu; Bo Zhou; Yang Lu; Jiaqing Zhang; Wujian Long; Lixiao Li. 3D printed polymeric formwork for lattice cementitious composites. Journal of Building Engineering 2021, 43, 103074 .
AMA StyleJian Song, Mengqin Cao, Lianmin Cai, Yizhou Zhou, Junying Chen, Su Liu, Bo Zhou, Yang Lu, Jiaqing Zhang, Wujian Long, Lixiao Li. 3D printed polymeric formwork for lattice cementitious composites. Journal of Building Engineering. 2021; 43 ():103074.
Chicago/Turabian StyleJian Song; Mengqin Cao; Lianmin Cai; Yizhou Zhou; Junying Chen; Su Liu; Bo Zhou; Yang Lu; Jiaqing Zhang; Wujian Long; Lixiao Li. 2021. "3D printed polymeric formwork for lattice cementitious composites." Journal of Building Engineering 43, no. : 103074.
Alkali-activated materials (AAMs) are widely recognized as potential alternatives to ordinary Portland cement (OPC) due to their lower carbon footprint. However, like OPC, AAMs can also generate some durable problems when exposed to aggressive environments and the mechanisms and possible improvements are still not fully clear in existing investigations. Furthermore, the corrosion mechanisms of AAMs are different from OPC due to the discrepant reaction products and pore structures. Thus, this study’s aim is to review the chemical reaction mechanisms, factors, and mitigation methods when AAMs are attacked by carbonation and chloride ions, along with a summative discussion regarding instructive insights to durable problems of AAMs.
Xuanhan Zhang; Kaidi Long; Wei Liu; Lixiao Li; Wu-Jian Long. Carbonation and Chloride Ions’ Penetration of Alkali-Activated Materials: A Review. Molecules 2020, 25, 5074 .
AMA StyleXuanhan Zhang, Kaidi Long, Wei Liu, Lixiao Li, Wu-Jian Long. Carbonation and Chloride Ions’ Penetration of Alkali-Activated Materials: A Review. Molecules. 2020; 25 (21):5074.
Chicago/Turabian StyleXuanhan Zhang; Kaidi Long; Wei Liu; Lixiao Li; Wu-Jian Long. 2020. "Carbonation and Chloride Ions’ Penetration of Alkali-Activated Materials: A Review." Molecules 25, no. 21: 5074.
Wind characteristics (e.g., mean wind speed, gust factor, turbulence intensity and integral scale, etc.) are quite scattered in different measurement conditions, especially during typhoon and/or hurricane processes, which results in the structural engineer ambiguously determining the wind parameters in wind-resistant design of buildings and structures in cyclone-prone regions. In tropical cyclones (including typhoons and hurricanes), the inconsistent wind characteristics may be in part ascribed to the complex flow structure with the coexistence of both mechanical and convective turbulence in the boundary layer of tropical cyclones. Another significant contribution to the scattered wind characteristics is due to various measurement conditions (e.g., terrain exposure and height) and data processing schemes (e.g., averaging time). The removal of the inconsistency in the field-measurement system may offer a more rational comparison of measured wind data from various observation platforms, and hence facilitates a better identification scheme of the wind characteristics to guide the urban planning design and wind-resistant design of buildings and structures. In this study, an analytical framework was firstly proposed to eliminate the potential observation-related effects in wind characteristics and then the wind characteristics of seven field measured tropical cyclones (four typhoons and three hurricanes) were comparatively investigated. Specifically, field measurements of wind characteristics were converted to a standard reference station with a roughness length of 0.03 m, observation duration of 10 min for mean wind and averaging time of 3 s for gusty wind at a 10 m height. The differences of the measured wind characteristics between the typhoons and hurricanes were highlighted. The standardized turbulent wind characteristics under the analytical framework for typhoons and hurricanes were compared with the corresponding recommendations in standard of American Society of Civil Engineers (ASCE 7-10) and Architectural Institute of Japan Recommendations for Loads on Buildings (AIJ-RLB-2004).
Lixiao Li; Yizhuo Zhou; Haifeng Wang; Haijun Zhou; Xuhui He; And Teng Wu; Zhou. An Analytical Framework for the Investigation of Tropical Cyclone Wind Characteristics over Different Measurement Conditions. Applied Sciences 2019, 9, 5385 .
AMA StyleLixiao Li, Yizhuo Zhou, Haifeng Wang, Haijun Zhou, Xuhui He, And Teng Wu, Zhou. An Analytical Framework for the Investigation of Tropical Cyclone Wind Characteristics over Different Measurement Conditions. Applied Sciences. 2019; 9 (24):5385.
Chicago/Turabian StyleLixiao Li; Yizhuo Zhou; Haifeng Wang; Haijun Zhou; Xuhui He; And Teng Wu; Zhou. 2019. "An Analytical Framework for the Investigation of Tropical Cyclone Wind Characteristics over Different Measurement Conditions." Applied Sciences 9, no. 24: 5385.
This study evaluated the performance of wind energy harvesters with multiple shape-optimized circular cylinders in tandem via computational fluid dynamics simulations. The circular cylinders were optimized by attaching triangular protrusions on their surface. The circumferential location of the protrusion plays a crucial role in the efficiency of this kind of wind energy harvester. The protrusions at the circumferential angles of α = 60°and 90°significantly extend the wind velocity range with remarkable energy generation. When the reduced wind velocity is lower than 10, the harvester with three plain cylinders in tandem generates the most power. However, when the speed is higher than 10, the most power is generated by the harvester having three cylinders in tandem with protrusions at α = 60°. Therefore, in a low wind velocity environment, the harvester with three plain circular cylinders in tandem is superior to other tested configurations, whereas in a high wind velocity environment, the harvester with three circular cylinders with protrusions at α = 60°in tandem outstands from other tested configurations. The associated flow mechanisms are detailed as well.
Gang Hu; Fengxi Liu; Lixiao Li; Chao Li; Yiqing Xiao; K.C.S. Kwok. Wind energy harvesting performance of tandem circular cylinders with triangular protrusions. Journal of Fluids and Structures 2019, 91, 102780 .
AMA StyleGang Hu, Fengxi Liu, Lixiao Li, Chao Li, Yiqing Xiao, K.C.S. Kwok. Wind energy harvesting performance of tandem circular cylinders with triangular protrusions. Journal of Fluids and Structures. 2019; 91 ():102780.
Chicago/Turabian StyleGang Hu; Fengxi Liu; Lixiao Li; Chao Li; Yiqing Xiao; K.C.S. Kwok. 2019. "Wind energy harvesting performance of tandem circular cylinders with triangular protrusions." Journal of Fluids and Structures 91, no. : 102780.
This paper extends previous studies concerning the structure of wind in tropical cyclones (TCs) approaching land mass over coastal waters. New sets of field measurements from wind observation towers and Doppler SODARS at levels between the land surface and 100 m height are presented. The measured mean (over 10-min periods) of the horizontal velocity U(r) shows the usual eye, eyewall and outer vortex structure. But very significantly they also exhibit that the mean vertical profile, U(z), does not increase monotonically as in a usual surface boundary layer in the backside eyewall regions. Rather, it is in the form of a jet, with a maximum velocity, ULLJ, at a height zLLJ, lying between 40 and 60 m. The data also show that the mean velocity gradient, defined by the ratio ULLJ/U(10), is typically smaller in the front side of a tropical cyclone in the direction of its motion as compared to the backside. This asymmetric distribution does not vary significantly with the radius. The mechanisms that result in the asymmetric distribution of the low-level jet are complex. One possible source is the downward transportation of convective turbulence. In the backside of a TC, the downflow is dominated, and it transports high velocity flow downward and enhances the mean momentum of wind flow at lower heights. Another factor may be the influence of the swell translation in different azimuth of a TC structure. These mechanisms need further investigation based on high resolution observations through a collaborative multiplatform measurement involving, e.g., Doppler SODAR, conventional sensors and numerical simulations.
Lixiao Li; Ahsan Kareem; Julian Hunt; Feng Xing; Pak Wai Chan; Yiqing Xiao; Chao Li. Observed sub-hectometer-scale low level jets in surface-layer velocity profiles of landfalling typhoons. Journal of Wind Engineering and Industrial Aerodynamics 2019, 190, 151 -165.
AMA StyleLixiao Li, Ahsan Kareem, Julian Hunt, Feng Xing, Pak Wai Chan, Yiqing Xiao, Chao Li. Observed sub-hectometer-scale low level jets in surface-layer velocity profiles of landfalling typhoons. Journal of Wind Engineering and Industrial Aerodynamics. 2019; 190 ():151-165.
Chicago/Turabian StyleLixiao Li; Ahsan Kareem; Julian Hunt; Feng Xing; Pak Wai Chan; Yiqing Xiao; Chao Li. 2019. "Observed sub-hectometer-scale low level jets in surface-layer velocity profiles of landfalling typhoons." Journal of Wind Engineering and Industrial Aerodynamics 190, no. : 151-165.
Architectural glass, especially the float glass, is a fragile part of a building. The architectural glass becomes a large amount of high-speed flying debris under bomb attacks and accidental explosions, thereby causing serious threat to residents. This study investigates the dynamic responses of a normal float glass subjected to blast loading using the explicit dynamic finite element software LS-DYNA. A JH-2 material model, which considers the strain rate effect and damage accumulation, is adopted for the float glass. A preliminary study shows that the present numerical model combined with reasonable material parameters can simulate the failure mode of the glass and the ejection velocity of glass fragments after failure. The verified model is then used to investigate the dynamic damage responses of the float glass under different loading cases. The damage assessment criterion of float glass is established on the basis of the glazing protection levels defined by the General Services Administration of the United States. Comprehensive simulations are conducted on different amounts of explosive and standoff distances. The degrees of glass damage under different loading cases are determined by combining the projection velocity of glass fragments after failure with a kinematic equation. Finally, the damage assessment diagram of float glass under different amounts of explosive is presented and compared with those in FEMA 426.
Xiaoqing Zhou; Ming-Yu Wang; Li-Xiao Li. Dynamic damage assessment of float glass under blast loading. Advances in Structural Engineering 2019, 22, 2517 -2529.
AMA StyleXiaoqing Zhou, Ming-Yu Wang, Li-Xiao Li. Dynamic damage assessment of float glass under blast loading. Advances in Structural Engineering. 2019; 22 (11):2517-2529.
Chicago/Turabian StyleXiaoqing Zhou; Ming-Yu Wang; Li-Xiao Li. 2019. "Dynamic damage assessment of float glass under blast loading." Advances in Structural Engineering 22, no. 11: 2517-2529.
Optimization method has been widely acknowledged as an effective approach to design engineering structures, and yet few studies adopt this method to design cellular materials. Here, we firstly adopted a Kriging assisted Multi-objective Genetic Algorithm to guideline the design of octet-truss (OCT) cellular materials with the maximum specific modulus. Subsequently, additional struts were artificially introduced into the optimized OCT to further mechanically reinforce performances. All the cellular materials were precisely fabricated using a Stereolithography 3D printing technique. By reasonably optimizing the sizes of OCT, the optimized OCT with a 1.112 mm diameter and 8.282 mm cell length was achieved, which displays a superior modulus-to-mass ratio. The highest modulus and strength of as-designed cellular materials achieved 34.12 MPa and 2.64 MPa, reinforced by ~3.11 and 4.81 times, respectively. Additionally, the absorbed energy efficiencies of them improved from 74.75% to 90.80%, which are significantly higher than other cellular materials. By in situ tests and fracture analyses, the high recoverability is attributed to the comprehensive effect of net-shaped architecture and elastic-plastic deformation.
Jian Song; Wenzhao Zhou; Yuejiao Wang; Rong Fan; Yinchu Wang; Junying Chen; Yang Lu; Lixiao Li. Octet-truss cellular materials for improved mechanical properties and specific energy absorption. Materials & Design 2019, 173, 107773 .
AMA StyleJian Song, Wenzhao Zhou, Yuejiao Wang, Rong Fan, Yinchu Wang, Junying Chen, Yang Lu, Lixiao Li. Octet-truss cellular materials for improved mechanical properties and specific energy absorption. Materials & Design. 2019; 173 ():107773.
Chicago/Turabian StyleJian Song; Wenzhao Zhou; Yuejiao Wang; Rong Fan; Yinchu Wang; Junying Chen; Yang Lu; Lixiao Li. 2019. "Octet-truss cellular materials for improved mechanical properties and specific energy absorption." Materials & Design 173, no. : 107773.
Calcium leaching is a degradation progress inside hardened cement composites, where Ca2+ ions in cement pore solution can migrate into the aggressive solution. In this work, calcium leaching of graphene oxide (GO) reinforced cement composites was effectively characterized by combined techniques of electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). Inhibiting mechanism of GO on calcium leaching of the composites was also examined. The obtained results show that the diameter of the semi-circle of the Nyquist curves of leached samples with GO addition decreased less than that of controlled samples. After leaching for 35 days, loss rate of model impedance RCCP of leached samples with 0, 0.05, 0.1, 0.15, and 0.2 wt.% GO addition was 94.85%, 84.07%, 79.66%, 75.34%, and 68.75%, respectively. Therefore, GO addition can significantly mitigate calcium leaching of cement composites, since it can absorb Ca2+ ions in cement pore solution, as well as improve the microstructure of the composites. In addition, coupling leaching depth and compressive strength loss were accurately predicted by using the impedance RCCP.
Wu-Jian Long; Tao-Hua Ye; Li-Xiao Li; Gan-Lin Feng. Electrochemical Characterization and Inhibiting Mechanism on Calcium Leaching of Graphene Oxide Reinforced Cement Composites. Nanomaterials 2019, 9, 288 .
AMA StyleWu-Jian Long, Tao-Hua Ye, Li-Xiao Li, Gan-Lin Feng. Electrochemical Characterization and Inhibiting Mechanism on Calcium Leaching of Graphene Oxide Reinforced Cement Composites. Nanomaterials. 2019; 9 (2):288.
Chicago/Turabian StyleWu-Jian Long; Tao-Hua Ye; Li-Xiao Li; Gan-Lin Feng. 2019. "Electrochemical Characterization and Inhibiting Mechanism on Calcium Leaching of Graphene Oxide Reinforced Cement Composites." Nanomaterials 9, no. 2: 288.
Optimization design assisted with advanced additive manufacturing techniques opens an effective gate for us to create novel, lightweight, mechanically robust cellular materials. Among them, lattice materials with an ordered cellular architecture have been known for their high mechanical properties, low density and energy absorption capacity. Limitedly, what kinds of topologic architecture have the best performance? And how could we obtain the optimized architecture? To answer them, we here took up two challenging tasks to achieve a novel compression-resistant lattice: ① The topology optimization method was introduced to design the optimized topologic architecture. ② Metallization was used to form lattice composites to further enhance the mechanical properties of pristine polymer. The topology optimization-guided lattice with only 20% volume of solid materials quite resembles the microstructure of cuttlebone, giving an indication of a good compression-resistant ability. Furthermore, the synthesized composites exhibit high specific compressive modulus of 5417.02 MPa kg−1 and energy absorption efficiency of 78%. By in situ compressive tests, digital image correlation, finite element simulation and fracture analysis, the deformation mechanism, and fracture modes were unambiguously revealed. The design strategies and findings shed light on the realization of advanced materials with tailored mechanical properties.
Jian Song; Yuejiao Wang; Wenzhao Zhou; Rong Fan; Bin Yu; Yang Lu; Lixiao Li. Topology optimization-guided lattice composites and their mechanical characterizations. Composites Part B: Engineering 2018, 160, 402 -411.
AMA StyleJian Song, Yuejiao Wang, Wenzhao Zhou, Rong Fan, Bin Yu, Yang Lu, Lixiao Li. Topology optimization-guided lattice composites and their mechanical characterizations. Composites Part B: Engineering. 2018; 160 ():402-411.
Chicago/Turabian StyleJian Song; Yuejiao Wang; Wenzhao Zhou; Rong Fan; Bin Yu; Yang Lu; Lixiao Li. 2018. "Topology optimization-guided lattice composites and their mechanical characterizations." Composites Part B: Engineering 160, no. : 402-411.
Wearable triboelectric nanogenerators (TENGs) have attracted interest in recent years, which demand highly flexible, scalable, and low-cost features. Here, we report an ultra-flexible, large-scale and textile-based TENG (T-TENG) for scavenging human motion energy. The triboelectric layer was derived from the polydimethylsiloxane (PDMS) film with a cost-effective paper-induced rough surface via a facile doctor-blending technology. Ag-coated chinlon fabric (ACF) with ultra-flexible, large-scale and conductive characteristics was used as the electrode. The as-fabricated PDMS-based ACF (PACF) composites possess a 240 × 300 mm2 superficial area and remain highly flexible under mechanical squeezing, folding and even tearing deformation. The maximum output charge of ~21 μC and voltage of 80.40 V were therefore achieved to directly power 100 LEDs based on the high surface area of 762.73 mm2 which was rationally replicated from the sandpaper of the T-TENG. Moreover, the output voltage signal can be also used as a trigger signal of a movement sensor. Importantly, the explicit theoretical model corresponding to T-TENG was quantitatively investigated under different applied force, frequency and effective surface factor.
Jian Song; Libo Gao; XiaoMing Tao; Lixiao Li. Ultra-Flexible and Large-Area Textile-Based Triboelectric Nanogenerators with a Sandpaper-Induced Surface Microstructure. Materials 2018, 11, 2120 .
AMA StyleJian Song, Libo Gao, XiaoMing Tao, Lixiao Li. Ultra-Flexible and Large-Area Textile-Based Triboelectric Nanogenerators with a Sandpaper-Induced Surface Microstructure. Materials. 2018; 11 (11):2120.
Chicago/Turabian StyleJian Song; Libo Gao; XiaoMing Tao; Lixiao Li. 2018. "Ultra-Flexible and Large-Area Textile-Based Triboelectric Nanogenerators with a Sandpaper-Induced Surface Microstructure." Materials 11, no. 11: 2120.
Reinforcement corrosion is a major cause of degradation in reinforced concrete structures. The fragile rust layer and cracking and spalling of the cover caused by splitting stress due to rust expansion can alter bond behaviors significantly. Despite extensive experimental tests, no stochastic model has yet incorporated randomness into the bond parameters model. This paper gathered published experimental data on the bond-slip parameters of pull-out specimens and beam-end specimens. Regression analysis was carried out to identify the best fit of bond strength and the corresponding slip value in the context of different corrosion levels from the recollected test results. An F-test confirmed the regression effect to be significant. Residual data were also analyzed and found to be well described by a normal distribution. Crack width data of the tested specimens were also collected. A regression analysis of the bond strength and maximum crack width was carried out given the comparative simplicity of measuring crack width versus rebar area loss. Results indicate that maximum crack width can also be used to predict bond strength degradation with similar variation magnitude.
H. J. Zhou; Y. F. Zhou; Y. N. Xu; Z. Y. Lin; F. Xing; L. X. Li. Regression Analysis of Bond Parameters between Corroded Rebar and Concrete Based on Reported Test Data. International Journal of Corrosion 2018, 2018, 1 -18.
AMA StyleH. J. Zhou, Y. F. Zhou, Y. N. Xu, Z. Y. Lin, F. Xing, L. X. Li. Regression Analysis of Bond Parameters between Corroded Rebar and Concrete Based on Reported Test Data. International Journal of Corrosion. 2018; 2018 ():1-18.
Chicago/Turabian StyleH. J. Zhou; Y. F. Zhou; Y. N. Xu; Z. Y. Lin; F. Xing; L. X. Li. 2018. "Regression Analysis of Bond Parameters between Corroded Rebar and Concrete Based on Reported Test Data." International Journal of Corrosion 2018, no. : 1-18.