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Effect of Recycled Aggregate and Slag as Substitutes for Natural Aggregate and Cement on the Properties of Concrete:A Review

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Journal of Renewable Materials 2023年第4期11卷 1853-1879页

作者： Peng Zhang wenshuai wang Yuanxun Zheng Shaowei Hu School of Water Conservancy Engineering Zhengzhou UniversityZhengzhou450001China Yellow River Laboratory Zhengzhou UniversityZhengzhou450001China College of Civil Engineering Chongqing UniversityChongqing400045China

Using recycled aggregate(RA)and slag instead of natural aggregate(NA)and cement can reduce greenhouse gas emissions(GHGE)and achieve effective waste *** recent years,RA has been widely used to replace NA in *** year,several researchers conduct investigations on the mechanical performance and durability of recycled aggregate concrete(RAC).Due to the loose and porous material properties of RA,the mechanical properties and durability of RAC,such as strength,carbonation resistance,permeability resistance and chloride ion penetration resistance,are greatly reduced compared with natural aggregate *** contrast,concrete containing slag instead of NA and cement generally improved the strength of concrete and reduced the internal porosity of ***,we discuss the effects of RA and slag on the workability,compressive strength,splitting tensile strength,ultrasonic pulse velocity(UPV)value,and elastic modulus of *** relationships between the compressive strength and the splitting tensile strength,UPV value,and elastic modulus are discussed,and the optimal substitution method is *** addition,various equations for calculating the compressive strength of concrete based on performance factors related to the compressive strength are summarized.

关键词： Recycled aggregate concrete slag concrete workability mechanical performance prediction equations

Fracture analysis of cortical bone under the condition of cement line debonding and osteon pullout

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International Journal of Biomathematics 2018年第2期11卷 175-188页

作者： Yaogeng Chen wenshuai wang Xing Li School of Mathematics and Statistics Ningxia University Yinchuan Ningxia 750021 P. R. China School of Science Ningxia Medical University Yinchuan Ningxia 750004 P. R. China

Cortical bone consists of osteons embedded in interstitial bone tissue and there is a thin amorphous interface, named cement line, between osteon and interstitial bone. Due to fatigue and cyclic loading, the pullout or debonding phenomenon often occurs in osteonal and interstitial tissue bone. The study aims to construct a fiber-reinforced composite material debonding model for cortical bone, in which the bonding condition along the osteon, cement line and interstitial tissue bone are assumed to be imperfect. In the study, we used the complex variable method to obtain series representations for stress fields in the osteon, cement line and the interstitial tissue bone with a radial crack. The effects of material properties of osteon and cement line, crack position, and varying degrees of debonding on the fracture behavior were investigated by computing the stress intensity factor （SIF） in the vicinity of the microcrack tips. The investigation results indicated that the cement line was important for controlling the fracture toughening mechanisms and that the level of imperfect bonding among osteon, cement line and interstitial tissue bone had a pronounced effect on the crack behavior and should not be ignored.

关键词： Cortical bone debonding cement line complex variables method.

Design equations for maximum stress concentration factors for concrete-filled steel tubular K-joints

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第5期11卷 1001-1022页

作者： Lei Jiang Yongjian Liu Neil AHoult Xin Long wenshuai wang School of Highway Chang'an UniversityXi'an 710064China Department of Civil Engineering Queen's UniversityKingstonON K7L 3N6Canada CCCC Second Highway Consultants Co. Ltd.Wuhan 430056China Research and Development Center of Life Cycle BIM Technologies Application Shandong Provincial Communications Planning and Design Institute Group Co.Ltd.Jinan 250101China

Stress concentration factors(SCFs) for welded tubular joints can be decreased by filling the chord with concrete leading to a longer fatigue life. However, there are currently no design formula available in guidelines to predict the SCF of concrete-filled circular hollow section(CFCHS) K-joints, thus limiting their applicability in bridge design. To address this gap,finite element models for CFCHS K-joints were developed and compared against test results to ensure their accuracy. Then, a comprehensive parametric study was conducted to establish relationships between maximum SCFs and four variables: brace-to-chord diameter ratio(β), chord diameter-to-thickness ratio(2γ), brace-to-chord thickness ratio(τ), and the angle between braces and chord(θ). A total of 480 FE models were examined under three loading conditions including brace and chord loading: balanced axial force, chord axial force, and chord bending. Design equations to predict the maximum SCF for CFCHS Kjoints were established by multiple regression analyses of the numerical results. A comparison of maximum SCFs between circular hollow section(CHS) and CFCHS K-joints was made, and it was concluded that average reductions of 42% and 33% in maximum SCFs in CFCHS K-joints at the locations of the chord and brace were found compared to CHS joints for balanced axial force, respectively. Finally, a case study illustrating how to use the proposed equations for fatigue safety verification was presented.

关键词： Steel tubular joint Concrete-filled Fatigue behaviour Design equations Stress concentration factor Numerical analysis

An eikonal equation-based earthquake location method by inversion of multiple phase arrivals

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Science China Earth Sciences 2024年第6期67卷 1802-1817页

作者： Gaoyue LAO Dinghui YANG Shaolin LIU Guiju DONG wenshuai wang Kui LIU National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing 100085China School of Earth Sciences Yunnan UniversityKunming 650091China Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China School of Mathematics and Statistics Ningxia UniversityYinchuan 750021China

The precise determination of earthquake location is the fundamental basis in seismological community,and is crucial for analyzing seismic activity and performing seismic *** arrivals are generally used to practically determine earthquake ***,first-arrival traveltimes are not sensitive to focal ***,they cannot accurately constrain focal *** improve the accuracy,researchers have analyzed the depth phases of earthquake *** traveltimes of depth phases are sensitive to focal depths,and the joint inversion of depth phases and direct phases can be implemented to potentially obtain accurate earthquake ***,researchers can determine earthquake locations in layered *** layered models can only represent the first-order feature of subsurface structures,the advantages of joint inversion are not fully explored if layered models are *** resolve the issue of current joint inversions,we use the traveltimes of three seismic phases to determine earthquake locations in heterogeneous *** three seismic phases used in this study are the first P-,sPg-and *** calculate the traveltimes of the three seismic phases by solving an eikonal equation with an upwind difference scheme and use the traveltimes to determine earthquake *** verify the accuracy of the earthquake location method by the inversion of three seismic phases,we take the 2021 M_(S)6.4 Yangbi,Yunnan earthquake as an example and locate this earthquake using synthetic and real seismic *** tests demonstrate that the eikonal equation-based earthquake location method,which involves the inversion of multiple phase arrivals,can effectively improve earthquake location accuracy.

关键词： Earthquake location Eikonal equation Fast marching method Heterogeneous model

A Generalized Block-by-block Method for the System of Linear Volterra Integral Equations of the Second Kind

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Wuhan University Journal of Natural Sciences 2011年第6期16卷 465-468页

作者： wang wenshuai wang Xu Institute of Geology and Geophysics Chinese Academy ofSciences Beijing 100029 China School of Mathematics and Computer Science NingxiaUniversity Yinchuan 750021 Ningxia China

In this paper, we provide a generalized block-by-block method for constructing block-by-block systems to solve the system of linear Volterra integral equations of the second kind, and then deduce some of the special cases. Compared with the expansion method and He＇s homotopy perturbation method, respectively numerical examples are given to certify the effectiveness of the method. The results show that the block-by-block method is very effective, simple, and of high accuracy in solving the system of linear Volterra integral equations of the second kind.

关键词： block-by-block method the system of linear Volterraintegral equations numerical solution

A Numerical Algorithm for Arbitrary Real-Order Hankel Transform

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Wuhan University Journal of Natural Sciences 2022年第1期27卷 26-34页

作者： YANG Yonglin LI Xing DING Shenghu wang wenshuai School of Mathematics and Statistics Ningxia UniversityYinchuan 750021NingxiaChina

The Hankel transform is widely used to solve various engineering and physics problems,such as the representation of electromagnetic field components in the medium,the representation of dynamic stress intensity factors,vibration of axisymmetric infinite membrane and displacement intensity factors which all involve this type of ***,traditional numerical integration algorithms cannot be used due to the high oscillation characteristics of the Bessel function,so it is particularly important to propose a high precision and efficient numerical algorithm for calculating the integral of high *** this paper,the improved Gaver-Stehfest(G-S)inverse Laplace transform method for arbitrary real-order Bessel function integration is presented by using the asymptotic characteristics of the Bessel function and the accumulation of integration,and the optimized G-S coefficients are *** effectiveness of the algorithm is verified by numerical *** with the linear transformation accelerated convergence algorithm,it shows that the G-S inverse Laplace transform method is suitable for arbitrary real order Hankel transform,and the time consumption is relatively stable and short,which provides a reliable calculation method for the study of electromagnetic mechanics,wave propagation,and fracture dynamics.

关键词： Hankel transform large argument approximate expression of the Bessel function linear transformation accelerated convergence algorithm(LTACA) G-S inverse Laplace transform method(G-SILTM)

Cortical Bone Model with a Microcrack under Tensile Loading

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Wuhan University Journal of Natural Sciences 2022年第5期27卷 375-382页

作者： wang Xu CHEN Yaogeng DING Shenghu wang wenshuai LI Xing School of Mathematics and Statistics Ningxia UniversityYinchuan 750021NingxiaChina School of Science Ningxia Medical UniversityYinchuan 750004NingxiaChina

The fracture mechanics of cortical bone has received much attention in biomedical *** is a fundamental question how the material constants and the geometric parameters of the cortical bone affect the fracture behavior of the cortical *** this work,the plane problem for cortical bone with a microcrack located in the interstitial tissue under tensile loading was *** the solution for the continuously distributed edge dislocations as Green ’ s functions,the problem was formulated as singular integral equations with Cauchy *** numerical results suggest that a soft osteon promotes microcrack propagation,while a stiff osteon repels it,but the interaction effect between the microcrack and the osteon is limited near the *** study not only sheds light on the fracture mechanics behavior of cortical bone but also offers inspiration for the design of bioinspired materials in biomedical engineering.

关键词： cortical bone microcrack singular integral equation Cauchy kernel stress intensity factor

Fekete-Szeg? Functional Problems for Certain Subclasses of Bi-Univalent Functions Involving the Hohlov Operator

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Journal of Mathematical Research with Applications 2020年第1期40卷 1-12页

作者： Pinhong LONG Huo TANG wenshuai wang School of Mathematics and Statistics Ningxia University School of Mathematics and Statistics Chifeng University

In the paper the new subclasses ■ and ■ of the function class ∑ of bi-univalent functions involving the Hohlov operator are introduced and ***, the corresponding Fekete-Szeg functional inequalities as well as the bound estimates of the coefficients a2and a3are obtained. Furthermore, several consequences and connections to some of the earlier known results also are given.

关键词： Fekete-Szeg? problem analytic function bi-univalent function Gaussian hypergeometric function Hohlov operator

Velocity structure and radial anisotropy beneath the northeastern Tibetan Plateau revealed by eikonal equation-based teleseismic P-wave traveltime tomography

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Science China Earth Sciences 2022年第5期65卷 824-844页

作者： Mengyang LI Shaolin LIU Dinghui YANG Xiwei XU Wenhao SHEN Chaodi XIE wenshuai wang Shuxin YANG National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing 100085China School of Earth Sciences Yunnan UniversityKunming 650091China Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China School of Mathematics and Statistics Ningxia UniversityYinchuan 750021China

The northeastern Tibetan Plateau serves as the frontier for the northeastward expansion of the *** this area,the Tibetan Plateau interacts with the surrounding blocks,such as the Alxa Block,the Ordos Block,the Kunlun-West Qinling belt and the Sichuan *** of this expansion and interaction,this area suffers from intense *** present,the evolution and deformation mechanisms of the northeastern Tibetan Plateau remain *** provide new insights into these mechanisms,in this study,we conduct tomography of the P-wave velocity and radial anisotropy structures beneath the northeastern Tibetan *** choose a total of 667 teleseismic earthquakes from August 2006 to October *** of these earthquakes were recorded by 921 broadband seismic stations in the northeastern Tibetan Plateau and surrounding *** first perform cross-correlation on waveforms of each station pair and obtain 770,749 P-wave traveltime ***,we invert the differential traveltime data by applying eikonal equation-based teleseismic ***,the P-wave velocity and radial anisotropy structures at depths from 30 to 800 km below the northeastern Tibetan Plateau are *** tomographic model shows clear low-velocity anomalies and positive radial anisotropy in the lower crust under the northeastern Qilian orogen,the northeastern Songpan-Ganzi belt and the western Qinling fold *** features are integrated to demonstrate the existence of lower crustal flow in the study *** low-velocity anomalies and positive radial anisotropy are found in the uppermost mantle beneath the Qilian orogen,the northeastern Songpan-Ganzi belt and western Qinling fold *** characteristics are combined to infer a weak lithosphere and horizontal asthenospheric flow under these tectonic *** the Ordos Block and the Sichuan Basin exhibit clear high-velocity anomalies and negative radial anisotropy in the uppermost mantle,thereby reflect

关键词： Northeastern Tibetan Plateau Tomography P-wave velocity Radial anisotropy structure Indian plate