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Micromixing performance of the teethed high shear mixer under semi-batch operation

《化学科学与工程前沿（英文）》 2022年 第16卷 第4期   页码 546-559 doi: 10.1007/s11705-021-2069-3

摘要： Semi-batch operated reaction processes are necessary for some competitive reaction systems to achieve a desirable process selectivity and productivity of fine chemical products. Herein the structural and operating parameters of the teethed high shear mixers were adjusted to study the micromixing performance in the semi-batch operated system, using the Villermaux/Dushman reaction system. The results indicate that the rising of the rotor speed and the number of rotor teeth, the decrease of the width of the shear gap and the radial distance between the feed position and the inner wall of stator can enhance the micromixing level and lead to the decrease of the segregation index. Additionally, computational fluid dynamics calculations were carried out to disclose the evolution of the flow pattern and turbulent energy dissipation rate of the semi-batch operated high shear mixer. Furthermore, the correlation was established with a mean relative error of 8.05% and R2 of 0.955 to fit the segregation index and the parameters studied in this work, which can provide valuable guidance on the design and optimization of the semi-batch operated high shear mixers in practical applications.

关键词： high shear mixer     semi-batch operation     micromixing performance     Villermaux/Dushman system     segregation index    

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Effects of rotor and stator geometry on dissolution process and power consumption in jet-flow high shear

Lin Yang, Wenpeng Li, Junheng Guo, Wei Li, Baoguo Wang, Minqing Zhang, Jinli Zhang

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 384-398 doi: 10.1007/s11705-020-1928-7

摘要： The jet-flow high shear mixer (JF-HSM) is a new type of intensified equipment with special configurations of the rotor and the stator. The mass transfer property and power consumption were studied in the solid-liquid system for a series of JF-HSMs involving different configuration parameters, such as rotor diameter, rotor blade inclination, rotor blade bending direction, stator diameter, and stator bottom opening diameter. The flow characteristics were examined by computational fluid dynamic simulations. Results indicate that the turbulent power consumption of the JF-HSM is affected by the change in rotor blade inclination and stator bottom opening. With the increase in the shear head size and the change in the rotor into a backward-curved blade, the solid-liquid mass transfer rate can be remarkably increased under the same input power. Dimensionless correlations for the mass transfer coefficient and power consumption were obtained to guide the scale-up design and selection of such a new type of equipment to intensify the overall mixing efficiency.

关键词： jet-flow high shear mixer     solid particle dissolution     power consumption characteristics     CFD Simulation    

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Slender reinforced concrete shear walls with high-strength concrete boundary elements

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 138-151 doi: 10.1007/s11709-022-0897-y

摘要： Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词： slender walls     high-strength concrete     rectangular and barbell-shaped walls     cold joints    

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Behavior and strength of headed stud shear connectors in ultra-high performance concrete of composite

Jianan QI, Yuqing HU, Jingquan WANG, Wenchao LI

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1138-1149 doi: 10.1007/s11709-019-0542-6

摘要： This study presents an experimental and numerical investigation on the static behavior of headed stud shear connectors in ultra-high performance concrete (UHPC) of composite bridges. Four push-out specimens were tested. It was found that no cracking, crushing or splitting was observed on the concrete slab, indicating that UHPC slab exhibited good performance and could resist the high force transferred from the headed studs. The numerical and experimental results indicated that the shear capacity is supposed to be composed of two parts stud shank shear contribution and concrete wedge block shear contribution. The stiffness increment of a stud in UHPC was at least 60% higher than that in normal strength concrete. Even if the stud height was reduced from 6 to 2 , there was no reduction in the shear strength of a stud. Short stud shear connectors with an aspect ratio as small as 2 could develop full strength in UHPC slabs. An empirical load-slip equation taking into account stud diameter was proposed to predict the load-slip response of a stud. The reliability and accuracy of the proposed load-slip equation was verified by the experimental and numerical load-slip curves.

关键词： ultra-high performance concrete     studs     shear strength     FE analysis     push-out test    

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Combined static mixers for high viscous fluids mixing

Zhenhao XI, Weizhen SUN, Ling ZHAO, Zhaoyan LIU

《化学科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 93-96 doi: 10.1007/s11705-009-0112-x

摘要： A new static mixer Cross-over-Disc has been invented to strip off the boundary layer and to make strong radial mixing. The pressure drop of Cross-over-Disc is 12—26 times as large as that of empty pipe with equivalent diameter and length. The mixing performance of Cross-over-Disc with 14 elements has been investigated in the viscosity range of 190—250 Pa?s by decoloration method, and the gray analysis of images shows that mixing inhomogeneity is about 7.5% and 9.4% for the mixing ratio of 5∶1 and 10∶1, respectively. Furthermore, mixing inhomogeneity for a combination of static mixing elements (four from Cross-over-Disc and three pairs from Sulzer-type) can be decreased to 2.1%—3.1% within a reasonable range of pressure drop.

关键词： static mixer     Cross-over-Disc     pressure drop     mixing performance     high viscous fluid    

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Flexural and longitudinal shear performance of precast lightweight steel–ultra-high performance concrete

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 704-721 doi: 10.1007/s11709-023-0941-6

摘要： In this study, the flexural and longitudinal shear performances of two types of precast lightweight steel–ultra-high performance concrete (UHPC) composite beams are investigated, where a cluster UHPC slab (CUS) and a normal UHPC slab (NUS) are connected to a steel beam using headed studs through discontinuous shear pockets and full-length shear pockets, respectively. Results show that the longitudinal shear force of the CUS is greater than that of the NUS, whereas the interfacial slip of the former is smaller. Owing to its better integrity, the CUS exhibits greater flexural stiffness and a higher ultimate bearing capacity than the NUS. To further optimize the design parameters of the CUS, a parametric study is conducted to investigate their effects on the flexural and longitudinal shear performances. The square shear pocket is shown to be more applicable for the CUS, as the optimal spacing between two shear pockets is 650 mm. Moreover, a design method for transverse reinforcement is proposed; the transverse reinforcement is used to withstand the splitting force caused by studs in the shear pocket and prevent the UHPC slab from cracking. According to calculation results, the transverse reinforcement can be canceled when the compressive strength of UHPC is 150 MPa and the volume fraction of steel fiber exceeds 2.0%.

关键词： precast steel–UHPC composite beam     flexural performance     longitudinal shear performance     parametric study     transverse reinforcement ratio    

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Shear behavior of ultra-high-performance concrete beams prestressed with external carbon fiber-reinforced

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1426-1440 doi: 10.1007/s11709-021-0783-z

摘要： The ultra-high-performance concrete (UHPC) and fiber-reinforced polymer (FRP) are well-accepted high-performance materials in the field of civil engineering. The combination of these advanced materials could contribute to improvement of structural performance and corrosion resistance. Unfortunately, only limited studies are available for shear behavior of UHPC beams reinforced with FRP bars, and few suggestions exist for prediction methods for shear capacity. This paper presents an experimental investigation on the shear behavior of UHPC beams reinforced with glass FRP (GFRP) and prestressed with external carbon FRP (CFRP) tendons. The failure mode of all specimens with various shear span to depth ratios from 1.7 to 4.5 was diagonal tension failure. The shear span to depth ratio had a significant influence on the shear capacity, and the effective prestressing stress affected the crack propagation. The experimental results were then applied to evaluate the equations given in different codes/recommendations for FRP-reinforced concrete structures or UHPC structures. The comparison results indicate that NF P 18-710 and JSCE CES82 could appropriately estimate shear capacity of the slender specimens with a shear span to depth ratio of 4.5. Further, a new shear design equation was proposed to take into account the effect of the shear span to depth ratio and the steel fiber content on shear capacity.

关键词： beam     external prestressing     ultra-high-performance concrete     fiber-reinforced polymers     shear behavior     design equation    

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Shear design of high strength concrete prestressed girders

Emad L. LABIB,Hemant B. DHONDE,Thomas T. C. HSU,Y. L. MO

《结构与土木工程前沿（英文）》 2014年 第8卷 第4期   页码 373-387 doi: 10.1007/s11709-014-0087-7

摘要： Normal strength prestressed concrete I-girders are commonly used as the primary superstructure components in highway bridges. However, shear design guidelines for high strength PC girders are not available in the current structural codes. Recently, ten 7.62 m (25 feet) long girders made with high strength concrete were designed, cast, and tested at the University of Houston (UH) to study the ultimate shear strength and the shear concrete contribution ( ) as a function of concrete strength ( ). A simple semi-empirical set of equations was developed based on the test results to predict the ultimate shear strength of prestressed concrete I-girders. The UH-developed set of equations is a function of concrete strength ( ), web area ( ), shear span to effective depth ratio ( / ), and percentage of transverse steel ( ). The proposed UH-Method was found to accurately predict the ultimate shear strength of PC girders with concrete strength up to 117 MPa (17000 psi) ensuring satisfactory ductility. The UH-Method was found to be not as overly conservative as the ACI-318 (2011) code provisions, and also not to overestimate the ultimate shear strength of high strength PC girders as the AASHTO LRFD (2010) code provisions. Moreover, the proposed UH-Method was found fairly accurate and not exceedingly conservative in predicting the concrete contribution to shear for concrete strength up to 117 MPa (17000 psi).

关键词： shear design     high strength concrete     prestressed girders     full-scale tests    

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Erratum to: Folded down-conversion mixer for a 60 GHz receiver architecture in 65-nm CMOS technology

Najam Muhammad AMIN,Zhi-gong WANG,Zhi-qun LI

《信息与电子工程前沿（英文）》 2015年 第16卷 第5期 doi: 10.1631/FITEE.14e0087

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Modeling of shear walls using finite shear connector elements based on continuum plasticity

Ulf Arne GIRHAMMAR, Per Johan GUSTAFSSON, Bo KÄLLSNER

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 143-157 doi: 10.1007/s11709-016-0377-3

摘要： Light-frame timber buildings are often stabilized against lateral loads by using diaphragm action of roofs, floors and walls. The mechanical behavior of the sheathing-to-framing joints has a significant impact on the structural performance of shear walls. Most sheathing-to-framing joints show nonlinear load-displacement characteristics with plastic behavior. This paper is focused on the finite element modeling of shear walls. The purpose is to present a new shear connector element based on the theory of continuum plasticity. The incremental load-displacement relationship is derived based on the elastic-plastic stiffness tensor including the elastic stiffness tensor, the plastic modulus, a function representing the yield criterion and a hardening rule, and function representing the plastic potential. The plastic properties are determined from experimental results obtained from testing actual connections. Load-displacement curves for shear walls are calculated using the shear connector model and they are compared with experimental and other computational results. Also, the ultimate horizontal load-carrying capacity is compared to results obtained by an analytical plastic design method. Good agreements are found.

关键词： shear walls     wall diaphragms     finite element modelling     plastic shear connector     analytical modelling     experimental comparison    

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Dynamic analyses of steel-reinforced super high-strength concrete columns

JIA Jinqing, JIANG Rui, XU Shilang, HOU Tong

《结构与土木工程前沿（英文）》 2007年 第1卷 第2期   页码 240-246 doi: 10.1007/s11709-007-0030-2

摘要： The dynamic behaviors of steel-reinforced super high-strength concrete columns under seismic loading were studied with a series of experiments. Thirteen specimens, with concrete strengths ranging from 94.9 to 105.4 MPa and shear-span ratios of 2.75, were manufactured. The axial load ratio and the stirrup reinforcement ratio were the main experimental variables affecting the dynamic behavior of the specimens. The columns under low cyclic lateral loading mainly failed in the flexural-shear mode. Shear force-displacement hysteretic curves and skeleton curves were drawn. The coefficients of the specimens displacement ductility were calculated. Experimental results indicate that ductility decreases while the axial load ratio increases, but it increases when the stirrup reinforcement ratio increases. The limit values of the axial load ratio and the minimum stirrup reinforcement ratio of the columns were investigated to satisfy definite ductility requirements. These values were suggested as references of engineering applications and of the amendment of the current Chinese design code of steel reinforced concrete composite structures.

关键词： amendment     flexural-shear     force-displacement hysteretic     definite ductility     skeleton    

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Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

Dan V. BOMPA, Ahmed Y. ELGHAZOULI

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 331-356 doi: 10.1007/s11709-019-0596-5

摘要： This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.

关键词： non-linear numerical modelling     concrete damage plasticity     RC flat slabs     shear-heads     punching shear    

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Behaviour of self-centring shear walls——A state of the art review

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 53-77 doi: 10.1007/s11709-022-0850-0

摘要： The application of unbonded post-tensioning (PT) in structural walls has led to the development of advanced self-centring (rocking) shear wall systems that has significant advantages, including accelerated construction due to the incorporation of prefabricated elements and segmental construction for different materials (e.g., concrete, masonry, and timber), reduced residual drifts, and little damage upon extreme seismic and wind loads. Concrete, masonry, and timber are often used for the construction of unbonded PT structural wall systems. Despite extensive research since the 1980s, there are no well-established design guidelines available on the shear wall configuration with the required energy dissipation system, joint’s locations and acceptance criteria for shear sliding, confinement, seismic performance factors, PT loss, PT force range and residual drifts of shear walls subjected to lateral loads. In this research a comprehensive state-of-the-art literature review was performed on self-centring shear wall system. An extensive study was carried out to collect a database of 100 concrete, masonry, and self-centring shear wall tests from the literature. The established database was then used to review shear walls’ configurations, material, and components to benchmark requirements applicable for design purposes. The behaviour of concrete, masonry and timber shear walls were compared and critically analysed. The general behaviour, force-displacement performance of the walls, ductility, and seismic response factors, were critically reviewed and analysed for different self-centring wall systems to understand the effect of different parameters including configurations of the walls, material used for construction of the wall (concrete, masonry, timber) and axial stress ratio. The outcome of this research can be used to better understand the behaviour of self-centring wall system in order to develop design guidelines for such walls.

关键词： self-centring shear walls     rocking walls     energy dissipation     seismic performance factors     PT loss     residual drift    

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Prediction of the shear wave velocity

Amoroso SARA

《结构与土木工程前沿（英文）》 2014年 第8卷 第1期   页码 83-92 doi: 10.1007/s11709-013-0234-6

摘要： The paper examines the correlations to obtain rough estimates of the shear wave velocity from non-seismic dilatometer tests (DMT) and cone penetration tests (CPT). While the direct measurement of is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of from the parameters (material index), (horizontal stress index), (constrained modulus) are more reliable and consistent than the CPT predictions from (cone resistance), presumably because of the availability, by DMT, of the stress history index .

关键词： horizontal stress index     shear wave velocity     flat dilatometer test     cone penetration test    

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On braced trapezoidal corrugated steel shear panels: An experimental and numerical study

《结构与土木工程前沿（英文）》 2023年 第17卷 第3期   页码 396-410 doi: 10.1007/s11709-023-0934-5

摘要： In this study, a new system consisting of a combination of braces and steel infill panels called the braced corrugated steel shear panel (BCSSP) is presented. To obtain the hysteretic behavior of the proposed system, the quasi-static cyclic performances of two experimental specimens were first evaluated. The finite element modeling method was then verified based on the obtained experimental results. Additional numerical evaluations were carried out to investigate the effects of different parameters on the system. Subsequently, a relationship was established to estimate the buckling shear strength of the system without considering residual stresses. The results obtained from the parametric study indicate that the corrugated steel shear panel (CSSP) with the specifications of a = 30 mm, t = 2 mm, and θ = 90° had the highest energy dissipation capacity and ultimate strength while the CSSP with the specifications of a = 30 mm, t = 2 mm, and θ = 30° had the highest initial stiffness. It can thus be concluded that the latter CSSP has the best structural performance and that increasing the number of corrugations, corrugation angle, and plate thickness and decreasing the sub-panel width generally enhance the performance of CSSPs in terms of the stability of their hysteretic behaviors.

关键词： trapezoidal corrugated plate     steel shear panel     braced steel shear panel     experimental study     buckling resistance.    

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标题 作者 时间 类型 操作

Micromixing performance of the teethed high shear mixer under semi-batch operation

期刊论文

Effects of rotor and stator geometry on dissolution process and power consumption in jet-flow high shear

Lin Yang, Wenpeng Li, Junheng Guo, Wei Li, Baoguo Wang, Minqing Zhang, Jinli Zhang

期刊论文

Slender reinforced concrete shear walls with high-strength concrete boundary elements

期刊论文

Behavior and strength of headed stud shear connectors in ultra-high performance concrete of composite

Jianan QI, Yuqing HU, Jingquan WANG, Wenchao LI

期刊论文

Combined static mixers for high viscous fluids mixing

Zhenhao XI, Weizhen SUN, Ling ZHAO, Zhaoyan LIU

期刊论文

Flexural and longitudinal shear performance of precast lightweight steel–ultra-high performance concrete

期刊论文

Shear behavior of ultra-high-performance concrete beams prestressed with external carbon fiber-reinforced

期刊论文

Shear design of high strength concrete prestressed girders

Emad L. LABIB,Hemant B. DHONDE,Thomas T. C. HSU,Y. L. MO

期刊论文

Erratum to: Folded down-conversion mixer for a 60 GHz receiver architecture in 65-nm CMOS technology

Najam Muhammad AMIN,Zhi-gong WANG,Zhi-qun LI

期刊论文

Modeling of shear walls using finite shear connector elements based on continuum plasticity

Ulf Arne GIRHAMMAR, Per Johan GUSTAFSSON, Bo KÄLLSNER

期刊论文

Dynamic analyses of steel-reinforced super high-strength concrete columns

JIA Jinqing, JIANG Rui, XU Shilang, HOU Tong

期刊论文

Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

Dan V. BOMPA, Ahmed Y. ELGHAZOULI

期刊论文

Behaviour of self-centring shear walls——A state of the art review

期刊论文

Prediction of the shear wave velocity

Amoroso SARA

期刊论文

On braced trapezoidal corrugated steel shear panels: An experimental and numerical study

期刊论文