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Jun Wu
School of Urban Railway Transportation, Shanghai University of Engineering Science, Shanghai 201620, China

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Journal article
Published: 10 January 2021 in Applied Sciences
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The thermomechanical coupling constitutive model of concrete is a critical subject for the theoretical investigation and numerical simulation of the mechanical behaviors of concrete members and structures at high temperature. This paper presents a thermomechanical coupling constitutive model for the description of the mechanical behaviors of concrete at different temperatures. The expression of the elastic strain increment is derived with the free energy function including the temperature variable. The expression of the plastic strain increment is derived from the yield function based on the Drucker–Prager strength criterion. The elastoplastic damage effect is included in this constitutive model. The damage variable is included in the yield function to consider the effect of the damage on the elastoplastic mechanical behaviors of concrete. The proposed constitutive model is validated by the comparison of the simulation results of the uniaxial compression tests of concrete at different temperatures with the corresponding test results. The simulation results accord well with the test results at different temperatures. This indicates that the proposed constitutive model can characterize the mechanical behaviors of concrete at different temperatures with considerable accuracy. The proposed constitutive model was applied to simulate an axially compressive concrete column. The simulation results are consistent with the essential mechanical response behaviors of concrete members at different temperatures.

ACS Style

Liang Li; Hongwei Wang; Jun Wu; Wenhua Jiang. A Thermomechanical Coupling Constitutive Model of Concrete Including Elastoplastic Damage. Applied Sciences 2021, 11, 604 .

AMA Style

Liang Li, Hongwei Wang, Jun Wu, Wenhua Jiang. A Thermomechanical Coupling Constitutive Model of Concrete Including Elastoplastic Damage. Applied Sciences. 2021; 11 (2):604.

Chicago/Turabian Style

Liang Li; Hongwei Wang; Jun Wu; Wenhua Jiang. 2021. "A Thermomechanical Coupling Constitutive Model of Concrete Including Elastoplastic Damage." Applied Sciences 11, no. 2: 604.

Journal article
Published: 21 August 2019 in Materials
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An engineered cementitious composite (ECC) was reinforced with a steel grid and fibers to improve its tensile strength and ductility. A series of tensile tests have been carried out to investigate the quasi-static tensile capacity of the reinforced ECC. The quasi-static tensile capacities of reinforced ECCs with different numbers of steel-grid layers, types of fibers (Polyvinyl alcohol (PVA) fiber, KEVLAR fiber, and polyethylene (PE) fiber), and volume fractions of fibers have been tested and compared. It is indicated by the test results that: (1) On the whole, the steel grid-PVA fiber and steel grid-KEVLAR fiber reinforced ECCs have high tensile strength and considerable energy dissipation performance, while the steel grid-PE fiber reinforced ECC exhibits excellent ductility. (2) The ultimate tensile strength of the reinforced ECC can be improved by the addition of steel grids. The maximal peak tensile stress increase is about 50-95% or 140-190% by adding one layer or two layers of steel grid, respectively. (3) The ultimate tensile strength of the reinforced ECC can be enhanced with the increase of fiber volume fraction. For a certain kind of fiber, a volume fraction between 1.5% and 2% grants the reinforced ECC the best tensile strength. Near the ultimate loading point, the reinforced ECC exhibits strain hardening behavior, and its peak tensile stress increases considerably. The energy dissipation performance of the reinforced ECC can also be remarkably enhanced by such an increase in fiber volume fraction. (4) The ductility of the steel grid-PVA fiber reinforced ECC can be improved by the addition of steel grids and the increase of fiber volume fraction. The ductility of the steel grid-KEVLAR fiber reinforced ECC can be improved by the addition of steel grids alone. The ductility and energy dissipation performance of the steel grid-PE fiber reinforced ECC can be improved with the increase of fiber volume fraction alone. A mechanical model for the quasi-static initial and ultimate tensile strength of the steel grid-fiber reinforced ECC is proposed. The model is validated by the test data from the quasi-static tension experiments on the steel grid-PE fiber reinforced ECC.

ACS Style

Liang Li; Wenli Liu; Wu; Jun Wu; Wenjie Wu; Meng Wu; Li; Liu. Experimental Investigation on the Quasi-Static Tensile Capacity of Engineered Cementitious Composites Reinforced with Steel Grid and Fibers. Materials 2019, 12, 2666 .

AMA Style

Liang Li, Wenli Liu, Wu, Jun Wu, Wenjie Wu, Meng Wu, Li, Liu. Experimental Investigation on the Quasi-Static Tensile Capacity of Engineered Cementitious Composites Reinforced with Steel Grid and Fibers. Materials. 2019; 12 (17):2666.

Chicago/Turabian Style

Liang Li; Wenli Liu; Wu; Jun Wu; Wenjie Wu; Meng Wu; Li; Liu. 2019. "Experimental Investigation on the Quasi-Static Tensile Capacity of Engineered Cementitious Composites Reinforced with Steel Grid and Fibers." Materials 12, no. 17: 2666.

Journal article
Published: 25 April 2019 in Engineering Structures
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In practice, infilled frame is a common structure but the contribution of infill walls is typically ignored in previous research on progressive collapse. To this end, numerical models based on solid-element are employed to investigate the behavior of reinforced concrete (RC) frames with concrete masonry infill walls under a middle column removal scenario (CRS). The numerical models of bare and infilled frames are initially validated through previous experimental results. Then the numerical models are used to illustrate the effects of infill walls on the load transfer mechanisms of the frames under a CRS and the interaction between infill walls and frame members. Thereafter, the size effect of the frame models is discussed and the numerical models are further extended to study the effects of pertinent geometric parameters on the progressive collapse behavior, including the height of partial-height infill walls, the opening position and area of wall panels as well as the number of stories. The results indicate that the load transfer mechanism of a two-story infilled frame in a middle CRS is the frame action provided by frame members and the truss mechanism provided by the interaction of infill walls and surrounding frame members, in which the latter remarkably enhances the initial structural stiffness and peak resistance. For the multi-story infilled frame with opening in which the geometric and mechanical properties are identical in each story, the load transfer mechanism is basically independent of the number of stories, whereas for the frame with full-height infill walls, the composite effect of multi-story walls is evident, increasing the peak structural resistance. Therefore, if each full-height infill wall is simplified into equivalent strut models in structural analysis, the results are underpredicted but on the safe side.

ACS Style

Jun Yu; Yi-Ping Gan; Jun Wu; Hao Wu. Effect of concrete masonry infill walls on progressive collapse performance of reinforced concrete infilled frames. Engineering Structures 2019, 191, 179 -193.

AMA Style

Jun Yu, Yi-Ping Gan, Jun Wu, Hao Wu. Effect of concrete masonry infill walls on progressive collapse performance of reinforced concrete infilled frames. Engineering Structures. 2019; 191 ():179-193.

Chicago/Turabian Style

Jun Yu; Yi-Ping Gan; Jun Wu; Hao Wu. 2019. "Effect of concrete masonry infill walls on progressive collapse performance of reinforced concrete infilled frames." Engineering Structures 191, no. : 179-193.

Chapter
Published: 28 December 2017 in Environmental and Human Impact of Buildings
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Conclusions for laboratory impact test, field blast test, interfacial test and numerical modeling for the proposed multi-layer pavement system will be drawn, and future research will be recommended.

ACS Style

Jun Wu; Hao Wu; Hong Wei Andy Tan; Soon Hoe Chew. Conclusions and Recommendations. Environmental and Human Impact of Buildings 2017, 207 -213.

AMA Style

Jun Wu, Hao Wu, Hong Wei Andy Tan, Soon Hoe Chew. Conclusions and Recommendations. Environmental and Human Impact of Buildings. 2017; ():207-213.

Chicago/Turabian Style

Jun Wu; Hao Wu; Hong Wei Andy Tan; Soon Hoe Chew. 2017. "Conclusions and Recommendations." Environmental and Human Impact of Buildings , no. : 207-213.

Journal article
Published: 17 February 2017 in Applied Sciences
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The behaviour of an asphalt concrete structure subjected to severe loading, such as blast and impact loadings, is becoming critical for safety and anti-terrorist reasons. With the development of high-speed computational capabilities, it is possible to carry out the numerical simulation of an asphalt concrete structure subjected to blast or impact loading. In the simulation, the constitutive model plays a key role as the model defines the essential physical mechanisms of the material under different stress and loading conditions. In this paper, the key features of the Karagozian and Case concrete model (KCC) adopted in LSDYNA are evaluated and discussed. The formulations of the strength surfaces and the damage factor in the KCC model are verified. Both static and dynamic tests are used to determine the parameters of asphalt concrete in the KCC model. The modified damage factor is proposed to represent the higher failure strain that can improve the simulation of the behaviour of AC material. Furthermore, a series test of the asphalt concrete structure subjected to blast and impact loadings is conducted and simulated by using the KCC model. The simulation results are then compared with those from both field and laboratory tests. The results show that the use of the KCC model to simulate asphalt concrete structures can reproduce similar results as the field and laboratory test.

ACS Style

Jun Wu; Liang Li; Xiuli Du; Xuemei Liu. Numerical Study on the Asphalt Concrete Structure for Blast and Impact Load Using the Karagozian and Case Concrete Model. Applied Sciences 2017, 7, 202 .

AMA Style

Jun Wu, Liang Li, Xiuli Du, Xuemei Liu. Numerical Study on the Asphalt Concrete Structure for Blast and Impact Load Using the Karagozian and Case Concrete Model. Applied Sciences. 2017; 7 (2):202.

Chicago/Turabian Style

Jun Wu; Liang Li; Xiuli Du; Xuemei Liu. 2017. "Numerical Study on the Asphalt Concrete Structure for Blast and Impact Load Using the Karagozian and Case Concrete Model." Applied Sciences 7, no. 2: 202.