The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
John J. Zahn - One of the best experts on this subject based on the ideXlab platform.
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Reliability of Bolted Wood Connections
Journal of Structural Engineering-asce, 1992Co-Authors: John J. ZahnAbstract:This report analyzes the implied reliability of current practice for the design of bolted wood connections. All U.S. data available to the writer were used. The resistance distribution was taken to be normal, and the coefficient of variation was obtained by pooling data from several sources, as long as the moisture condition, grain direction, Side‐Plate material, and species were alike. The reliability index for softwood connections is about 5; the index for hardwood connections is about 20% greater than that for softwood connections. A comparative study of data from six sources showed that reliability does not depend upon bolt length‐to‐diameter ratio, and the effects of wood moisture content and Side‐Plate material (steel or wood) are minimal. Two new codes are briefly examined and compared with current practice. Both of these codes contain radically reformed design criteria for bolted wood connections. The comparison shows that both new codes maintain the present level of reliability.
Natalia Nuño - One of the best experts on this subject based on the ideXlab platform.
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ON THE 2D SIMPLIFICATION OF 3D CEMENTLESS HIP STEM NUMERICAL MODELS
2018Co-Authors: M. Reimeringer, Gonzalez F. Quevedo, Natalia NuñoAbstract:IntroductionFinite element (FE) models are commonly used to analyse the mechanical behaviour of the bone under different conditions. They provide detail information but they can be numerically expensive and this limits their use in cases where large or numerous simulations are required. On the other hand, 2D models show less computational cost but the precision of results depends on the approach used for the simplification. Three 2D approaches are commonly used: models without Side-Plate (WOSP)[1]; models with variable thickness Side-Plate and constant cortical thickness (SPCT)[2]; models with Side-Plate and variable cortical thickness (SPVT)[3]. The aim of this study is to determine which 2D approach reproduces best the FE results obtained with a 3D model involving hip stems.MethodsThe 2D models were generated by the intersection of the 3D model with the stem symmetry plane. Three approaches were conSidered to assure 3D-2D correspondence: 1) conSider variable thickness for the cortical elements so that t...
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On the Two-Dimensional Simplification of Three-Dimensional Cementless Hip Stem Numerical Models.
Journal of biomechanical engineering, 2017Co-Authors: Fernando Quevedo Gonzalez, M. Reimeringer, Natalia NuñoAbstract:Three-dimensional (3D) finite element (FE) models are commonly used to analyze the mechanical behavior of the bone under different conditions (i.e., before and after arthroplasty). They can provide detailed information but they are numerically expensive and this limits their use in cases where large or numerous simulations are required. On the other hand, 2D models show less computational cost, but the precision of results depends on the approach used for the simplification. Two main questions arise: Are the 3D results adequately represented by a 2D section of the model? Which approach should be used to build a 2D model that provides reliable results compared to the 3D model? In this paper, we first evaluate if the stem symmetry plane used for generating the 2D models of bone-implant systems adequately represents the results of the full 3D model for stair climbing activity. Then, we explore three different approaches that have been used in the past for creating 2D models: (1) without Side-Plate (WOSP), (2) with variable thickness Side-Plate and constant cortical thickness (SPCT), and (3) with variable thickness Side-Plate and variable cortical thickness (SPVT). From the different approaches investigated, a 2D model including a Side-Plate best represents the results obtained with the full 3D model with much less computational cost. The Side-Plate needs to have variable thickness, while the cortical bone thickness can be kept constant.
Trygve Kristiansen - One of the best experts on this subject based on the ideXlab platform.
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An Experimental and Numerical Study of Added Mass and Damping for Side-by-Side Plates in Oscillating Flow
Journal of Offshore Mechanics and Arctic Engineering, 2020Co-Authors: Frøydis Solaas, Fredrik Mentzoni, Mia Abrahamsen-prsic, Trygve KristiansenAbstract:Abstract Forced harmonic oscillations of nine configurations consisting of horizontal Side-by-Side Plate elements are performed experimentally and numerically. The configurations are oscillated in vertical direction and represent generalized mudmats of subsea structures. The tests are performed for Keulegan–Carpenter (KC) numbers relevant for force estimation during lifting operations. Hydrodynamic added mass and damping coefficients are presented. The coefficients are found to be amplitude dependent for all tested configurations. The interaction effects between the Plates increase with increasing amplitude and decreasing distance between the Plates. For small oscillation amplitudes, compared with the gap between the Plates, the Plates behave approximately like individual Plates. A study of the relation between the damping force and the added mass force for the tested structures illustrates the importance of applying representative damping coefficients in numerical analysis of marine operations. Numerical results are obtained using a potential flow solver (BEM) and a viscous flow solver (CFD). Low-KC added mass coefficients predicted with the BEM are in accordance with the experiments. There is acceptable agreement between the CFD and the experiments. Best agreement is obtained for small KC numbers. As the KC numbers increase, the differences are, in general, larger. This is possibly due to the CFD being based on the two-dimensional laminar flow.
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An Experimental and Numerical Study of Added Mass and Damping for Side by Side Plates in Oscillating Flow
Volume 7A: Ocean Engineering, 2019Co-Authors: Frøydis Solaas, Fredrik Mentzoni, Mia Abrahamsen-prsic, Trygve KristiansenAbstract:Abstract Forced harmonic oscillations of seven configurations consisting of horizontal Side by Side Plate elements are performed experimentally and numerically. The configurations are oscillated in vertical direction and represent generalized mudmats of subsea structures. The tests are performed for Keulegan-Carpenter (KC) numbers relevant for force estimation during lifting operations. Hydrodynamic added mass and damping coefficients are presented. The coefficients are found to be amplitude dependent for all configurations tested. The interaction effects between the Plates increase with increasing amplitude and decreasing distance between the Plates. For oscillation amplitudes small compared with the gap between the Plates, the Plates behave approximately like individual Plates. A study of the relation between the damping force and the added mass force for the tested structures illustrates the importance of applying representative damping coefficients in numerical analysis of marine operations. Numerical results are obtained using a potential flow solver (BEM) and a viscous flow solver (CFD). Low-KC added mass coefficients predicted with the BEM are in accordance with the experiments. There is acceptable agreement between the CFD and the experiments. Best agreement is obtained for small KC numbers. For increasing KC numbers, the differences are, in general, larger. This is possibly due to the CFD being based on two-dimensional laminar flow.
Chih-kai Jao - One of the best experts on this subject based on the ideXlab platform.
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Seismic rehabilitation performance of steel Side Plate moment connections
Earthquake Engineering & Structural Dynamics, 2009Co-Authors: Chung-che Chou, Keh-chyuan Tsai, Yuang-yu Wang, Chih-kai JaoAbstract:Moment connections in an existing steel building located in Kaohsiung, Taiwan were rehabilitated to satisfy seismic requirements based on the 2005 AISC seismic provisions. Construction of the building was ceased in 1996 due to financial difficulties and was recommenced in 2007 with enhanced connection performance. Steel moment connections in the existing building were constructed by groove welding the beam flanges and bolting the beam web to the column. Four moment connections, two from the existing steel building, were cyclically tested. A non-rehabilitated moment connection with bolted web-welded flanges was tested as a benchmark. Three moment connections rehabilitated by welding full-depth Side Plates between the column face and beam flange inner Side were tested to validate the rehabilitation performance. Test results revealed that (1) the non-rehabilitated existing moment connection made by in situ welding process prior to 1996 had similar deformation capacity as contemporary connection specimens made by laboratory welding process, (2) all rehabilitated moment connections exhibited excellent performance, exceeding a 4% drift without fractures of beam flange groove-welded joints, and (3) presence of the full-depth Side Plates effectively reduced beam flange tensile strain near the column face by almost half compared with the non-rehabilitated moment connection. The connection specimens were also modeled using the non-linear finite element computer program ABAQUS to further confirm the effectiveness of the Side Plate in transferring beam moments to the column and to investigate potential sources of connection failure. A design procedure was made based on experimental and analytical studies.
C. Phornputkul - One of the best experts on this subject based on the ideXlab platform.
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Two-hole Side-Plate DHS in the treatment of intertrochanteric fracture: Results and complications
Injury, 2005Co-Authors: Anupong Laohapoonrungsee, Olarn Arpornchayanon, C. PhornputkulAbstract:We reviewed 83 intertrochanteric fractures fixed with a 135 degree dynamic hip screw (DHS) and two-hole Side-Plate. The mean age was 72 years. There were 13 A1.1, 24 A1.2, 16 A2.1, 29 A2.2 and 1 A2.3 fractures. Established osteoporosis was seen in 55 patients. The mean time to union was 14.5 weeks. Sixty-eight percent had minimal collapse, 24% moderate and 8% severe. Over 80% of moderate and severe collapses were associated with osteoporosis and an unstable fracture pattern. There were four failures: two from lag screw cut-out and two from pull-out of the Side-Plate.
