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学者姓名:李易
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摘要 :
In this paper, three precast concrete (PC) frames and one cast-in-situ reinforced-concrete (RC) frame were cast and tested to investigate the load-resisting mechanisms of emulative PC frames with various reinforcing details to resist progressive collapse. In the beams of PC frames, the top reinforcement was continuous without curtailment while the bottom reinforcement had different anchorage strength. Test results indicated that, in the event of middle column removal, similar to RC frame, beam action, compressive arch action (CAA), and tensile catenary action (TCA) could be developed sequentially in PC frames with emulative connections, PC frames with sufficient anchorage strength or additional bottom U-shaped bars passing through the middle joint could obtain similar level of CAA capacity as RC frame. However, they may achieve relatively lower TCA capacity due to higher bond strength between the top reinforcement and cast-in-situ topping layer in beams, owing to higher concrete strength in the topping layer, resulting in earlier fracture of the beam top reinforcements. Conversely, PC frames with insufficient anchorage could achieve comparable TCA capacity as RC frame. However, their CAA capacity was less than that of RC frames due to pulling-out failure of bottom reinforcements, preventing further development of strain hardening at beam action and CAA stages. Based on test results and analytical studies, it was found that, similar to RC frames, PC frames with emulative connections could provide sufficient rotational capacity to ensure development of tie-force as required by the design guidelines. (C) 2021 American Society of Civil Engineers.
关键词 :
Emulative connection Emulative connection Experimental tests Experimental tests Precast concrete Precast concrete Progressive collapse Progressive collapse
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GB/T 7714 | Qian, Kai , Liang, Shi-Lin , Fu, Feng et al. Progressive Collapse Resistance of Emulative Precast Concrete Frames with Various Reinforcing Details [J]. | JOURNAL OF STRUCTURAL ENGINEERING , 2021 , 147 (8) . |
MLA | Qian, Kai et al. "Progressive Collapse Resistance of Emulative Precast Concrete Frames with Various Reinforcing Details" . | JOURNAL OF STRUCTURAL ENGINEERING 147 . 8 (2021) . |
APA | Qian, Kai , Liang, Shi-Lin , Fu, Feng , Li, Yi . Progressive Collapse Resistance of Emulative Precast Concrete Frames with Various Reinforcing Details . | JOURNAL OF STRUCTURAL ENGINEERING , 2021 , 147 (8) . |
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摘要 :
To enhance post-punching strengths and deformation capacities of flat plate-column joints for mitigating progressive collapse, two strengthening methods including stirrups and embedded ring beams within the joint regions were proposed. An experimental test program on six flat plate-column joint specimens with in-plane constraints was conducted under the modes of upward punching shear failure (UPS mode) and downward punching shear failure (DPS mode). The specimens included two conventional specimens without strengthening (UPS/DPS), two specimens with stirrups (two-legged closed ties, UPS-S/DPS-S) and two specimens with ring beams (UPS-R/DPS-R). The test results showed that, in comparison to UPS/DPS, the average post-punching displacements in UPS-S/DPS-S and UPS-R/DPS-R were increased by 25% and 32%, respectively, along with 64% and 50% enhancement in the corresponding post-punching shear strengths. Numerical simulations were also performed to analyze the effects of different stirrup and ring beam configurations on the post-punching strengths and deformation capacities. Numerical results suggested that double stirrups (four-legged closed ties) installed surrounding the column stub could lessen joint damage and further improve punching shear and post-punching strengths by 15% and 9%, respectively, comparing to UPS-S/DPS-S. For ring beam specimens, under DPS mode, the first punching shear failure inside the ring beams can be prevented by their inner edges directly connected to the column. The post-punching deformations and strengths of this specimen were increased by at least 10%, comparing to DPS-R. Numerical simulation of UPS-R further showed that the strengthening effect also depends on the constraints provided by the concrete.
关键词 :
Embedded ring beams Embedded ring beams Flat plate-column joints Flat plate-column joints Post-punching performance Post-punching performance Reinforcement strengthening configuration Reinforcement strengthening configuration Stirrups Stirrups
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GB/T 7714 | Yang, Youzhe , Li, Yi , Guan, Hong et al. Enhancing post-punching performance of flat plate-column joints by different reinforcement configurations [J]. | JOURNAL OF BUILDING ENGINEERING , 2021 , 43 . |
MLA | Yang, Youzhe et al. "Enhancing post-punching performance of flat plate-column joints by different reinforcement configurations" . | JOURNAL OF BUILDING ENGINEERING 43 (2021) . |
APA | Yang, Youzhe , Li, Yi , Guan, Hong , Diao, Mengzhu , Lu, Xinzheng . Enhancing post-punching performance of flat plate-column joints by different reinforcement configurations . | JOURNAL OF BUILDING ENGINEERING , 2021 , 43 . |
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摘要 :
Progressive collapse of reinforced concrete flat plate systems can be significantly influenced by the post-punching performance of their slab-column joints under large deformations. This work presents a series of static collapse tests on four flat slab-column joint specimens with slab in-plane restraint. The effects of different punching directions (upward and downward) and embedded beams on the post-punching performance of the joints were studied. The test results reveal that the post-punching load-bearing and deformation capacities are mainly governed by the longitudinal through-column reinforcement in the slab. The peak bearing capacities and failure modes of specimens without embedded beams were significantly influenced by different punching directions. Conversely, the post-punching mechanisms of specimens with embedded beams were identical regardless of their opposite punching shear actions. In addition, the inclusion of the embedded beams increased the resistance capacity of the specimens under both flexural and suspension mechanisms and enhanced the deformation capacity under the suspension mechanism. Furthermore, a finite-element numerical model was developed and verified against the test results. Based on the numerical study, the contributions of the concrete and reinforcement in resisting the collapse of the slab-column joints were evaluated.
关键词 :
finite element methods finite element methods slabs & plates slabs & plates testing, structural elements testing, structural elements
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GB/T 7714 | Diao, Mengzhu , Li, Yi , Guan, Hong et al. Post-punching mechanisms of slab-column joints under upward and downward punching actions [J]. | MAGAZINE OF CONCRETE RESEARCH , 2021 , 73 (6) : 302-314 . |
MLA | Diao, Mengzhu et al. "Post-punching mechanisms of slab-column joints under upward and downward punching actions" . | MAGAZINE OF CONCRETE RESEARCH 73 . 6 (2021) : 302-314 . |
APA | Diao, Mengzhu , Li, Yi , Guan, Hong , Lu, Xinzheng , Xue, Huizhong , Hao, Zongda . Post-punching mechanisms of slab-column joints under upward and downward punching actions . | MAGAZINE OF CONCRETE RESEARCH , 2021 , 73 (6) , 302-314 . |
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摘要 :
Hydrophobic property of metal-organic frameworks (MOFs) is not only important for their stability improvement but also has a profound effect on the performance of many applications. The essence of coordination bonds led to most of the MOFs are hydrophilic and hydrophobic MOFs are generally achieved by hydrophobic modification of pore surface. Here, we report the systematic regulation of water adsorption and hydrophobic property of a classical MOF MIL-101(Cr) through post-synthetic modification. The contact angle (CA) of modified MIL-101 could vary from 17.9 degrees to 146.5 degrees by changing the alkyl chain length of primary amines. The water adsorption capacity and step pressure can also be tuned correspondingly.
关键词 :
Hydrophobic Hydrophobic Metal-organic framework Metal-organic framework MIL-101(Cr) MIL-101(Cr) Post-synthetic modification Post-synthetic modification Water adsorption Water adsorption
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GB/T 7714 | Li, Yi , Wang, Hao-Tian , Zhao, Yan-Long et al. Regulation of hydrophobicity and water adsorption of MIL-101(Cr) through post-synthetic modification [J]. | INORGANIC CHEMISTRY COMMUNICATIONS , 2021 , 130 . |
MLA | Li, Yi et al. "Regulation of hydrophobicity and water adsorption of MIL-101(Cr) through post-synthetic modification" . | INORGANIC CHEMISTRY COMMUNICATIONS 130 (2021) . |
APA | Li, Yi , Wang, Hao-Tian , Zhao, Yan-Long , Lv, Jie , Zhang, Xin , Chen, Qiang et al. Regulation of hydrophobicity and water adsorption of MIL-101(Cr) through post-synthetic modification . | INORGANIC CHEMISTRY COMMUNICATIONS , 2021 , 130 . |
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摘要 :
This study introduces a multiple-input convolutional neural network (MI-CNN) model for the seismic damage assessment of regional buildings. First, ground motion sequences together with building attribute data are adopted as inputs of the proposed MI-CNN model. Second, the prediction accuracy of MI-CNN model is discussed comprehensively for different scenarios. The overall prediction accuracy is 79.7%, and the prediction accuracies for all scenarios are above 77%, indicating a good prediction performance of the proposed method. The computation efficiency of the proposed method is 340 times faster than that of the nonlinear multi-degree-of-freedom shear model using time history analysis. Third, a case study is conducted for reinforced concrete (RC) frame buildings in Shenzhen city, and two seismic scenarios (i.e., M6.5 and M7.5) are studied for the area. The simulation results of the area indicate a good agreement between the MI-CNN model and the benchmark model. The outcomes of this study are expected to provide a useful reference for timely emergency response and disaster relief after earthquakes.
关键词 :
machine learning machine learning multiple-input convolutional neural network multiple-input convolutional neural network nonlinear time history analysis nonlinear time history analysis seismic damage assessment seismic damage assessment seismic response seismic response
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GB/T 7714 | Xiong, Chen , Zheng, Jie , Xu, Liangjin et al. Multiple-Input Convolutional Neural Network Model for Large-Scale Seismic Damage Assessment of Reinforced Concrete Frame Buildings [J]. | APPLIED SCIENCES-BASEL , 2021 , 11 (17) . |
MLA | Xiong, Chen et al. "Multiple-Input Convolutional Neural Network Model for Large-Scale Seismic Damage Assessment of Reinforced Concrete Frame Buildings" . | APPLIED SCIENCES-BASEL 11 . 17 (2021) . |
APA | Xiong, Chen , Zheng, Jie , Xu, Liangjin , Cen, Chengyu , Zheng, Ruihao , Li, Yi . Multiple-Input Convolutional Neural Network Model for Large-Scale Seismic Damage Assessment of Reinforced Concrete Frame Buildings . | APPLIED SCIENCES-BASEL , 2021 , 11 (17) . |
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摘要 :
In flat plate structures, interior slab-column joints are subjected to in-plane restraints and bending-shear actions, which can significantly impact their mechanical performance to resist progressive collapse. However, research in this area is still lacking. This paper presents experimental and numerical studies of pre-and post-punching performances of eccentrically loaded slab-column joints with in-plane restraints. Quasi-static tests were conducted on seven joint specimens, including one concentrically loaded (CL) joint and six eccentrically loaded (EL) ones. The effects of critical structural parameters (i.e., eccentricity, slab thickness and reinforcement ratio) on the pre-and post-punching performances were investigated by analysing the load-displacement relationships, failure modes and material strains. The experimental results indicated that larger eccentricity could lead to more reduction of the peak punching shear capacity by as much as 62%, whereas it has little effect on the post punching capacity. In addition, the strain results of the through-column rebars showed that, with the well restrained boundary conditions, the slab flexural reinforcement (FR) was found to resist the applied load to a large extent at small deformations and still able to contribute greatly during the post-punching stage. Numerical analysis was conducted to gain an in-depth understanding toward the effects of varied levels of in-plane restraints on both slab-column joints and actual flat plate structures. It was found that the lateral stiffnesses in the CL joint model with boundary beams and the substructure model were similar, which was around 400 N/mm. Finally, the interactions between the unbalanced moment and shear force were explored and compared with code predictions (ACI318-19 and EC2-04). Without considering the enhancement effects from in-plane restraints, the codes produced over-conservative predictions. Based on the FE analyses, the correlation between the dimensionless ratio e/d (eccentricity/effective thickness of slab) and punching shear strength was simplified by a combined straight line and a power curve.
关键词 :
Eccentric loading Eccentric loading In-plane restraint In-plane restraint Pre-and post-punching performances Pre-and post-punching performances Progressive collapse Progressive collapse Slab-column joint Slab-column joint
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GB/T 7714 | Diao, Mengzhu , Li, Yi , Guan, Hong et al. Pre- and post-punching performances of eccentrically loaded slab-column joints with in-plane restraints [J]. | ENGINEERING STRUCTURES , 2021 , 248 . |
MLA | Diao, Mengzhu et al. "Pre- and post-punching performances of eccentrically loaded slab-column joints with in-plane restraints" . | ENGINEERING STRUCTURES 248 (2021) . |
APA | Diao, Mengzhu , Li, Yi , Guan, Hong , Yang, Zhi , Gilbert, Benoit P. , Wang, Junkun . Pre- and post-punching performances of eccentrically loaded slab-column joints with in-plane restraints . | ENGINEERING STRUCTURES , 2021 , 248 . |
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摘要 :
The fine finite element models of slab-column joints were established according to the reinforcement detailing in real structures, in which the concrete and reinforcement were simulated by solid and beam elements, respectively. The element deactivation technique was adopted to simulate concrete cracking during the process of punching and the rupture of reinforcing bars after punching shear. The simulation method was validated via the comparison between the numerical and experimental results of three typical punching shear tests. The validation showed that the displacement and capacity of the punching and post-punching stages were accurately simulated by the developed method. Based on the numerical model, the analyses were further conducted to explore the mechanical behavior of the joints with in-plane constraints during a whole punching shear process. The results indicated that the contributions of integrity reinforcement and flexural reinforcement were 42% and 58%, respectively, to the post-punching resistances of the tested joints with in-plane constraints. The increase of reinforcement ratio leaded to the improvement of the stiffness of the joints at both punching and post-punching stages. On the other hand, increasing the slab thickness only significantly enhanced the capacity and stiffness of the joints before punching shear. That the redundant strength was at least 36% of the designed punching shear strength was found for the joints with in-plane constraints when using the calculation methods in European, American, Australian and Chinese codes. The predicted post-punching capacity calculated by the existing methods, in which the contribution of the flexural reinforcement was underestimated, was also lower than the tested capacity. © 2020, Engineering Mechanics Press. All right reserved.
关键词 :
Concretes Concretes Finite element method Finite element method Numerical methods Numerical methods Reinforcement Reinforcement Stiffness Stiffness
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GB/T 7714 | Yang, You-Zhe , Li, Yi , Zhou, Da-Xing et al. Fine finite element analysis of slab-column joints after punching shear [J]. | Engineering Mechanics , 2020 , 37 (6) : 206-215 . |
MLA | Yang, You-Zhe et al. "Fine finite element analysis of slab-column joints after punching shear" . | Engineering Mechanics 37 . 6 (2020) : 206-215 . |
APA | Yang, You-Zhe , Li, Yi , Zhou, Da-Xing , Lu, Xin-Zheng , Sun, Hai-Lin . Fine finite element analysis of slab-column joints after punching shear . | Engineering Mechanics , 2020 , 37 (6) , 206-215 . |
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摘要 :
This paper presents a fibre-beam-element based model to capture the progressive collapsemechanisms of reinforced concrete (RC) frames. The model is comprised of rectangular and T-section fibre-beam elements. A stress-strain relationship for the steel which considers the embedment of the reinforcing bars in the concrete, the effect of concrete confinement and the bond-slip between the concrete and reinforcements are also considered in the model. The accuracy of the model is verified against experimental tests performed on two asymmetric one-story beam-column specimens with flange slabs under different lateral restraints. The first specimen, referred to as "OP", was a two-bay frame subjected to a penultimate column removal scenario, while the other one, referred to as "OA", was a three-bay frame with an antepenult removal scenario. The simulation results agree well with the experimental results with prediction of the peak capacity being within 10%. The model is then used to gain an in-depth understanding of the failure mechanisms of the two tested specimens. Numerical results reveal that the progressive collapse resistance of the RC frames is primarily determined by the bending stiffness and capacity of the columns. Compared to OP, the extra bay in OA provided a larger horizontal restraint to the damaged beam-flange slab, leading to 115% and 650% larger axial forces at the peak resistances under the stages of compressive arch action (CAA) and catenary action (CA), respectively. Furthermore, the penultimate column in OA was found to damage prior to its edge column, owing to its close proximity to the missing column and the additional bending moment MF generated by the redistributed axial forces to the columns.
关键词 :
Numerical simulation Numerical simulation Penultimate and antepenult column removal scenarios Penultimate and antepenult column removal scenarios Progressive collapse Progressive collapse Reinforced concrete Reinforced concrete
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GB/T 7714 | Diao, M. Z. , Li, Y. , Guan, H. et al. Numerical Modelling of the Progressive Collapse of Reinforced Concrete Frames with Different Lateral Restraints [C] . 2020 : 755-763 . |
MLA | Diao, M. Z. et al. "Numerical Modelling of the Progressive Collapse of Reinforced Concrete Frames with Different Lateral Restraints" . (2020) : 755-763 . |
APA | Diao, M. Z. , Li, Y. , Guan, H. , Lu, X. Z. , Gilbert, B. P. . Numerical Modelling of the Progressive Collapse of Reinforced Concrete Frames with Different Lateral Restraints . (2020) : 755-763 . |
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摘要 :
The mechanical behavior of beam-column joints under large deformation is the key factor affecting the progressive collapse resistance of precast concrete frame structures with dry-connections. In this paper, a static progressive collapse test was conducted on three beam-column substructure specimens, including one bolted connection specimen, one unbonded prestressed connection specimen and one cast-in-situ specimen. The failure modes of joints and the static collapse resistance of substructures under different deformations were analyzed via test results. The dynamic collapse resistance of substructures was also investigated based on the energy conservation principle. Compared with the cast-in-situ specimen, the static and dynamic collapse resistances of the bolted connection specimen under the compression arch mechanism are reduced by 41% and 45%, respectively, due to the buckling of connection steel plate which has been exposed to the tensile force at beam ends. These resistances under the catenary mechanism are also reduced by 27% and 37%, respectively, owing to the fracture of connection angle steel and bolts. For the unbonded prestressed connection specimen, the static and dynamic collapse resistances under the compression arch mechanism are reduced by 39% and 45%, respectively, comparing with the cast-in-situ specimen due to the early crush of concrete. Although the static collapse resistance under the catenary mechanism is increased by 52%, which is contributed by the prestressed steel bars, the corresponding dynamic collapse resistance of the unbonded prestressed connection specimen is 17% lower than that of the cast-in-situ specimen due to the smaller accumulated dissipating energy under the compression arch mechanism. © 2020, Editorial Office of Journal of Building Structures. All right reserved.
关键词 :
Arches Arches Bolts Bolts Concrete testing Concrete testing Deformation Deformation Dynamics Dynamics Overhead lines Overhead lines Precast concrete Precast concrete Structural dynamics Structural dynamics
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GB/T 7714 | An, Yi , Li, Yi , Lu, Xinzheng et al. Static progressive collapse test on precast concrete frames with dry connections [J]. | Journal of Building Structures , 2020 , 41 (7) : 102-109 . |
MLA | An, Yi et al. "Static progressive collapse test on precast concrete frames with dry connections" . | Journal of Building Structures 41 . 7 (2020) : 102-109 . |
APA | An, Yi , Li, Yi , Lu, Xinzheng , Ren, Peiqi . Static progressive collapse test on precast concrete frames with dry connections . | Journal of Building Structures , 2020 , 41 (7) , 102-109 . |
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摘要 :
To investigate the influence of critical parameters on the progressive collapse resistance of reinforced concrete (RC)-flat plates, a set of finite-element modeling techniques was established. The modeling of bond-slip behavior between concrete and rebars was especially highlighted, which was found to have a significant impact on the performance of flat plates. Employing the modeling strategy, our previously tested 2 x 2-bay flat plate substructure (S-1) and a similar specimen (ND) in the literature were simulated for model validation. Key structural behaviors, including tensile membrane and suspension actions in the large deformation stage, could be accurately replicated. Further, the validated S-1 model was used to conduct a series of parametric studies in which the influence of concrete strength, slab thickness, and reinforcement ratio on the collapse performance was examined. The results indicated that the concrete strength and the slab thickness only affected the slab flexural capacity with no impact on the load-carrying capacity after the initial flexural/shear failure. Moreover, the load-carrying capacity due to tensile membrane action was primarily governed by the reinforcement ratio. Further examination on the lateral stiffness suggested a lower bound ultimate flexural strength enhancement of 17%, due to the compressive membrane action, can be obtained. (C) 2020 American Society of Civil Engineers.
关键词 :
Bond-slip model Bond-slip model Interior column loss Interior column loss Progressive collapse Progressive collapse Reinforced concrete (RC)-flat plates Reinforced concrete (RC)-flat plates
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GB/T 7714 | Xue, Huizhong , Guan, Hong , Gilbert, Benoit P. et al. Comparative and Parametric Studies on Behavior of RC-Flat Plates Subjected to Interior-Column Los [J]. | JOURNAL OF STRUCTURAL ENGINEERING , 2020 , 146 (9) . |
MLA | Xue, Huizhong et al. "Comparative and Parametric Studies on Behavior of RC-Flat Plates Subjected to Interior-Column Los" . | JOURNAL OF STRUCTURAL ENGINEERING 146 . 9 (2020) . |
APA | Xue, Huizhong , Guan, Hong , Gilbert, Benoit P. , Lu, Xinzheng , Li, Yi . Comparative and Parametric Studies on Behavior of RC-Flat Plates Subjected to Interior-Column Los . | JOURNAL OF STRUCTURAL ENGINEERING , 2020 , 146 (9) . |
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