The Experts below are selected from a list of 45 Experts worldwide ranked by ideXlab platform
Jinguang Teng - One of the best experts on this subject based on the ideXlab platform.
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Behavior and modelling of FRP-concrete-steel hybrid double-skin tubular columns under repeated unloading/Reloading Cycles
Composite Structures, 2021Co-Authors: Bing Zhang, Jinguang TengAbstract:Abstract Fiber-reinforced polymer (FRP)-concrete-steel hybrid double-skin tubular columns (hybrid DSTCs) consist of an outer FRP tube, an inner steel tube and a concrete infill between the two tubes. Extensive research has been conducted on the monotonic behavior of hybrid DSTCs, but only a limited number of studies have examined their behavior under cyclic axial compression. In particular, no systematic experimental study has been conducted on hybrid DSTCs under repeated unloading/Reloading Cycles. This paper first presents a systematic experimental study on hybrid DSTCs under two types of loading schemes: (a) a single unloading/Reloading Cycle to evaluate the relationship between the unloading strain and the plastic strain; (b) repeated unloading/Reloading Cycles to investigate the effect of loading history. In the present study, hybrid DSTCs were prepared using filament-wound FRP tubes of a relatively large scale (up to 300 mm in diameter), and the experimental program covered a wide range of concrete strengths (from 40.9 MPa to 104.4 MPa). The systematic experimental study with extensive instrumentation allowed the cyclic stress-strain behavior of the concrete in hybrid DSTCs to be examined in detail, clarifying the cumulative effect of the loading history on both the stress deterioration and the plastic strain of the concrete. This paper also presents a detailed comparison between the test results and the predictions of an existing cyclic stress-strain model for FRP-confined concrete in solid columns, in terms of the repeated unloading/Reloading Cycles. The cyclic stress-strain model is shown to provide reasonably accurate predictions, and thus can be used together with a monotonic stress-stress model for the concrete in hybrid DSTCs to predict the complete cyclic stress-strain curve of such concrete.
Lai Fei Cheng - One of the best experts on this subject based on the ideXlab platform.
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Proportional Limit Stress and Residual Thermal Stress of 3D SiC/SiC Composite
Journal of Materials Science & Technology, 2014Co-Authors: Shanhua Liu, Li Tong Zhang, Xiaowei Yin, Yongsheng Liu, Lai Fei ChengAbstract:Proportional limit stress (PLS) and residual thermal stresses (RTS) of 3D SiC/SiC composite were investigated. PLS was obtained by four different methods from the monotonic stress–strain response curve to get a convincing value. RTS in the SiC matrix was quantified by solving the geometric intersection point of the regression lines of hysteresis loops from the periodical loading–unloading–Reloading Cycle test curve. Classical ACK model and analytical formulas were used to analytically calculate the PLS and RTS of 3D SiC/SiC composite. Good agreement between the experimental results and the analytical calculation was observed. And relationship between the PLS and the RTS of 3D SiC/SiC was discussed.
Bing Zhang - One of the best experts on this subject based on the ideXlab platform.
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Behavior and modelling of FRP-concrete-steel hybrid double-skin tubular columns under repeated unloading/Reloading Cycles
Composite Structures, 2021Co-Authors: Bing Zhang, Jinguang TengAbstract:Abstract Fiber-reinforced polymer (FRP)-concrete-steel hybrid double-skin tubular columns (hybrid DSTCs) consist of an outer FRP tube, an inner steel tube and a concrete infill between the two tubes. Extensive research has been conducted on the monotonic behavior of hybrid DSTCs, but only a limited number of studies have examined their behavior under cyclic axial compression. In particular, no systematic experimental study has been conducted on hybrid DSTCs under repeated unloading/Reloading Cycles. This paper first presents a systematic experimental study on hybrid DSTCs under two types of loading schemes: (a) a single unloading/Reloading Cycle to evaluate the relationship between the unloading strain and the plastic strain; (b) repeated unloading/Reloading Cycles to investigate the effect of loading history. In the present study, hybrid DSTCs were prepared using filament-wound FRP tubes of a relatively large scale (up to 300 mm in diameter), and the experimental program covered a wide range of concrete strengths (from 40.9 MPa to 104.4 MPa). The systematic experimental study with extensive instrumentation allowed the cyclic stress-strain behavior of the concrete in hybrid DSTCs to be examined in detail, clarifying the cumulative effect of the loading history on both the stress deterioration and the plastic strain of the concrete. This paper also presents a detailed comparison between the test results and the predictions of an existing cyclic stress-strain model for FRP-confined concrete in solid columns, in terms of the repeated unloading/Reloading Cycles. The cyclic stress-strain model is shown to provide reasonably accurate predictions, and thus can be used together with a monotonic stress-stress model for the concrete in hybrid DSTCs to predict the complete cyclic stress-strain curve of such concrete.
J.e. Hoogenboom - One of the best experts on this subject based on the ideXlab platform.
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Optimization of nuclear reactor Reloading patterns
Annals of Operations Research, 1997Co-Authors: E. De Klerk, C. Roos, T. Terlaky, T. Illés, A.j. De Jong, J. Valkó, J.e. HoogenboomAbstract:The loading pattern of fuel bundles in a reactor core determines the characteristics of the Reloading Cycle. The problem of maximizing fuel utilization during a Cycle may be formu-lated as a nonlinear mixed integer programming (NLMIP) problem, but has until now mostly been treated by heuristic optimization methods like simulated annealing. This paper evaluates the performance of state-of-the-art nonlinear programming routines on a simplified model of this problem, and compares results with available heuristic solutions. Copyright Kluwer Academic Publishers 1997
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Optimization of nuclear reactor Reloading patterns
Annals of Operations Research, 1997Co-Authors: E. De Klerk, C. Roos, T. Terlaky, T. Illés, A.j. De Jong, J. Valkó, J.e. HoogenboomAbstract:The loading pattern of fuel bundles in a reactor core determines the characteristics of the Reloading Cycle. The problem of maximizing fuel utilization during a Cycle may be formu-lated as a nonlinear mixed integer programming (NLMIP) problem, but has until now mostly been treated by heuristic optimization methods like simulated annealing. This paper evaluates the performance of state-of-the-art nonlinear programming routines on a simplified model of this problem, and compares results with available heuristic solutions.
L. Bałachowski - One of the best experts on this subject based on the ideXlab platform.
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Use of calibration chamber as a large triaxial apparatus
Archives of Civil and Mechanical Engineering, 2006Co-Authors: L. BałachowskiAbstract:Wycinek kolumny żwirowej o długości 1 m i średnicy 0,53 m modelowano w komorze kalibracyjnej. Uformowaną i zagęszczoną próbkę konsolidowano w komorze przy zadanym napr ężeniu, a następnie zwiększano naprężenia pionowe, mierząc zmiany objętości w membranach górnej i dolnej oraz komorze wewnętrznej aparatu. Badania prowadzono do uzyskania odkształcenia pionowego próbki około 2%, przy którym występuje względna stabilizacja dewiatora naprężenia. Określono wartości kąta tarcia wewnętrznego oraz moduły odkształcenia masywu gruntowego przy dużych odkształceniach (0,5%) oraz w cyklu odciążenie—powtórne obciążenie. W ostatnim przypadku uzyskano wielokrotnie większe wartości modułu odkształcenia. Zastosowanie komory kalibracyjnej jako wielowymiarowego aparatu trójosiowego ściskania należy ograniczyć do zakresu odkształceń pionowych nie większych niż 2%. Poza tym zakresem naprężenia oraz przemieszczenia przekazywane na grunt przez membrany wypełnione wodą mogą być nierównomiernie rozłożone. W niektórych gruntach możliwe jest przeprowadzenie testu obciążenia masywu gruntowego w komorze z wykonaniem sondowania statycznego lub badania dylatometrycznego w komorze kalibracyjnej na tej samej próbce gruntu. A segment of a gravel column, 1 m high and 0.53 m in diameter, was modelled in a calibration chamber. The reconstituted sample was consolidated at a given confining pressure and then subjected to axial load exerted by the upper and lower membranes. Volumetric changes in both membranes and in internal chamber were measured. Up to 2% vertical strain was reached and internal friction angle was evaluated. Secant modulus of deformation was determined at considerable strains and at intermediate strain level in the unloading–Reloading Cycle. For the latter several times higher modulus was found.
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Use of calibration chamber as a large triaxial apparatus
Archives of Civil and Mechanical Engineering, 2006Co-Authors: L. BałachowskiAbstract:A segment of a gravel column, 1 m high and 0.53 m in diameter, was modelled in a calibration chamber. The reconstituted sample was consolidated at a given confining pressure and then subjected to axial load exerted by the upper and lower membranes. Volumetric changes in both membranes and in internal chamber were measured. Up to 2% vertical strain was reached and internal friction angle was evaluated. Secant modulus of deformation was determined at considerable strains and at intermediate strain level in the unloading–Reloading Cycle. For the latter several times higher modulus was found.