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Properties of Cementitious Rendering Mortar Prepared with Recycled Fine Aggregates

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Journal of Wuhan University of Technology(Materials Science) 2010年第6期25卷 1053-1056页

作者：潘智生 Department of civil and structural engineering The Hong Kong Polytechnic University

The results of an experimental study on investigating the properties of cementitious rendering mortars prepared with a recycled fine aggregate（RA） were *** RA was obtained from a recycling plant in which mixed demolition wastes were processed by mechanical crushing,sieving and sorting *** series of rendering mortar mixes were prepared with a constant water/cement and a constant aggregate/cement ratios of 0.55 and 3 *** sand and natural crushed rock fine were originally used in the two series separately,and they were consistently replaced by 25%,50%,75% and 100% by the recycled *** experimental results showed that mechanical properties,such as compressive strength,flexural strength and modulus of elasticity of the mortars prepared with the RA were lower than the mortars made with the natural ***,the bond strength at the interface between the mortar and masonry bricks determined by the Triplet test was found to be higher for the mortars prepared with the RA.

关键词： rendering mortar recycled fine aggregate triplet test mechanical properties

Peak earthquake response of structures under multi-component excitations

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Earthquake engineering and engineering Vibration 2007年第4期6卷 357-370页

作者： Jianwei Song Zach Liang Yi-Lun Chu George C. Lee Department of civil Structural and Environmental Engineering State University of New York at Buffalo USA

Accurate estimation of the peak seismic responses of structures is important in earthquake resistant design. The internal force distributions and the seismic responses of structures are quite complex, since ground motions are multidirectional. One key issue is the uncertainty of the incident angle between the directions of ground motion and the reference axes of the structure. Different assumed seismic incidences can result in different peak values within the scope of design spectrum analysis for a given structure and earthquake ground motion record combination. Using time history analysis to determine the maximum structural responses excited by a given earthquake record requires repetitive calculations to determine the critical incident angle. This paper presents a transformation approach for relatively accurate and rapid determination of the maximum peak responses of a linear structure subjected to three-dimensional excitations within all possible seismic incident angles. The responses can be deformations, internal forces, strains and so on. An irregular building structure model is established using SAP2000 program. Several typical earthquake records and an artificial white noise are applied to the structure model to illustrate the variation of the maximum structural responses for different incident angles. Numerical results show that for many structural parameters, the variation can be greater than 100%. This method can be directly applied to time history analysis of structures using existing computer software to determine the peak responses without carrying out the analyses for all possible incident angles. It can also be used to verify and/or modify aseismic designs by using response spectrum analysis.

关键词： multi-component ground motion time history analysis peak structural response axis rotation

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

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Frontiers of structural and civil engineering 2023年第1期17卷 138-151页

作者： Mohammad SYED Pinar OKUMUS Department of civil Structural and Environmental EngineeringUniversity at BuffaloBuffaloNY 14260USA

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

Seismic behavior of outrigger truss-wall shear connections using multiple steel angles

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Earthquake engineering and engineering Vibration 2016年第2期15卷 197-208页

作者： Li Xian Wang Wei Lü Henglin Zhang Guangchang State Key Laboratory for Geomechanics & Deep Underground engineering China University of Mining and Technology Jiangsu Key Laboratory of Environmental Impact and structural Safety in civil engineering School of Mechanics and Civil Engineering China University of Mining and Technology

An experimental investigation on the seismic behavior of a type of outrigger truss-reinforced concrete wall shear connection using multiple steel angles is presented. Six large-scale shear connection models, which involved a portion of reinforced concrete wall and a shear tab welded onto a steel endplate with three steel angles, were constructed and tested under combined actions of cyclic axial load and eccentric shear. The effects of embedment lengths of steel angles, wall boundary elements, types of anchor plates, and thicknesses of endplates were investigated. The test results indicate that properly detailed connections exhibit desirable seismic behavior and fail due to the ductile fracture of steel angles. Wall boundary elements provide beneficial confinement to the concrete surrounding steel angles and thus increase the strength and stiffness of connections. Connections using whole anchor plates are prone to suffer concrete pry-out failure while connections with thin endplates have a relatively low strength and fail due to large inelastic deformations of the endplates. The current design equations proposed by Chinese Standard 04G362 and Code GB50011 significantly underestimate the capacities of the connection models. A revised design method to account for the influence of previously mentioned test parameters was developed.

关键词： anchor truss suffer welded reinforced stiffness tensile desirable properly frames

Parallel finite element modeling of earthquake ground response and liquefaction

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Earthquake engineering and engineering Vibration 2004年第1期3卷 23-37页

作者：陆金池彭军 Ahmed Elgamal 杨朝晖 Kincho H.Law Department of structural engineering University of California Department of civil and Enviromental engineering Stanford University Department of civil and Enviromental engineering Stanford University

Parallel computing is a promising approach to alleviate the computational demand in conducting large-scale finite element *** paper presents a numerical modeling approach for earthquake ground response and liquefaction using the parallel nonlinear finite element program,ParCYCLIC,designed for distributed-memory message-passing parallel computer *** ParCYCLIC,finite elements are employed within an incremental plasticity,coupled solid-fluid formulation,A constitutive model calibrated by physical tests represents the salient characteristics of sand liquefaction and associated accumulation of shear *** elements of the computational strategy employed in ParCYCLIC include the development of a parallel sparse direct solver,the deployment of an automatic domain decomposer,and the use of the Multilevel Nested Dissection algorithm for ordering of the finite element *** results of centrifuge test models using ParCYCLIC are *** results from grid models and geotechnical simulations show that ParCYCLIC is efficiently scalable to a large number of processors.

关键词： parallel finite element domain decomposition liquefaction parallel speedup earthquake site amplification

Long term performance of recycled concrete beams with different water-cement ratio and recycled aggregate replacement rate

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Frontiers of structural and civil engineering 2022年第3期16卷 302-315页

作者： Jingwei YING Feiming SU Shuangren CHEN school of civil engineering and Architecture Guangxi UniversityNanning 530004China Key Laboratory of engineering Disaster Prevention and structural Safety of China Ministry of Education Guangxi Key Laboratory of Disaster Prevention and Engineering SafetySchool of Civil Engineering and ArchitectureGuangxi UniversityNanning530004China

The purpose of this study is to reveal the service performance of recycled aggregate concrete(RAC)components for different values of water-cement ratio and replacement rate of recycled coarse aggregate(RCA).Generally,the concrete strength decreases with the increase of the replacement rate of RCA,in order to meet the strength requirements when changing the replacement rate of RCA,it is necessary to change the water-cement ratio at the same ***,the axial compressive strengths of prism with 25 mix proportions,the short-term mechanical properties and long-term deformation properties of reinforced concrete beams were tested respectively by changing water-cement ratio and RCA replacement *** bearing capacity and the strain nephogram of samples under different loads were obtained using the Digital Image Correlation(DIC)method,and a self-made gravity loading experimental device was used for long-term deformation *** showed that the damage pattern of RAC was the same as that of natural aggregate concrete(NAC),but the brittleness was more *** brittleness of concrete before failure can be reduced more effectively by adjusting the replacement rate of RCA than by adjusting the water-cement *** water-cement ratio has an evident influence on the axial compressive strength and early creep of concrete,while the replacement rate of RCA has a remarkable effect on the long-term deformation of the concrete beams.

关键词： recycled concrete beam the replacement rate of recycled coarse aggregate water-cement ratio digital image correlation

Analysis and behaviour of FRP-confined short concrete columns subjected to eccentric loading

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2008年第1期9卷 38-49页

作者： Xing-fei YUAN Shao-hua XIA L. LAM S.T. SMITH Department of civil engineering Zhejiang University Hangzhou 310027 China school of civil and Environmental engineering The University of Adelaide Adelaide SA 5005 Australia Department of civil and structural engineering The Hong Kong Polytechnic University Hong Kong China Department of civil engineering Hong Kong University Hong Kong China

Fibre-reinforced polymer (FRP) composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete (RC) columns. To design FRP jackets safely and economically, the behaviour of such columns should be predicted first. This paper is concerned with the analysis and behaviour of FRP-confined RC circular and rectangular short col- umns subjected to eccentric loading. A simple design-oriented stress-strain model for FRP-confined concrete in a section analysis was first proposed. The accuracy was then proved by two test data. Following that, a parametric study including amount of FRP confinement, FRP strain capacity, unconfined concrete strength and shape of column section is provided. Some conclusions were obtained at the end of the paper. The work here will provide a comprehensive understanding of the behaviour of FRP-confined concrete columns. The simplicity of the model also enables a simple equivalent stress block to be developed for direct use in practical design.

关键词： Column FRP confinement Stress-strain model Section analysis Strength Ductility

Numerical analysis on seismic behavior of railway earth embankment: A case study

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Journal of Central South University 2016年第4期23卷 906-918页

作者：林宇亮石峰杨啸杨果林李丽民 school of civil engineering Central South University Department of civil engineering Monash University school of civil and Environmental engineering Hunan University of Science and Engineering

A numerical case study on the seismic behavior of embankment was carried out based on a prototype of earth embankment in Yun-Gui Railway （from Kunming City to Nanning City） in southwest of China. A full-scale model of earth embankment was established by means of numerical simulation with FLAC3D code. The numerical results were verified by shaking table test. The seismic behaviors of earth embankment were studied, including the horizontal acceleration response, the vertical acceleration response, the dynamic displacement response, and the block state of earth embankment. Results show that the acceleration magnification near the embankment slope is larger than that in internal earth embankment body. With the increase of input peak acceleration, the horizontal acceleration magnification presents a decreasing trend. The horizontal acceleration response at the top of embankment is more sensitive to the intensity of ground motion than that at the bottom of cmbankment. The embankment presents an obvious nonlinear-plastic characteristic when the input horizontal peak acceleration is larger than 0.3 g. The maximum residual deformation occurs in the middle of embankment slope surface instead of at the top of embankment. The upper part of embankment experiences tension failure without shear failure, and area at mainly presents shear failure under the earthquake loading. surface of earth embankment. the bottom of embankment around the symmetry-axis of embankment The tension failure and shear failure repeatedly occur along the slope

关键词： earth embankment numerical analysis seismic behavior earthquake

Coupled model of consolidation and creep for consolidation test

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Journal of Central South University 2008年第S1期15卷 357-361页

作者：梅国雄殷建华 College of civil engineering Nanjing University of Technology Department of civil & structural engineering The Hong Kong Polytechnic University

For most soft soil,the consolidation process and the creep process were coupled and the character of settlement time curve was obtained by the consolidation test at the same time.A simple and continuous function was presented to express the whole process of consolidation including immediate settlement stage,the primary consolidation stage and the secondary consolidation *** the features of the continuous function were *** results of the long-term(duration to 18 months) consolidation test on clays from the Chek Lap Kok formation proved the rightness of the *** the end,the parameter meanings of the continuous function were discussed.

关键词： coupled model consolidation creep soft soil