scholarly journals A New Design Problem in the Formulation of a Special Moment Resisting Connection Device for Preventing Local Buckling

2021 ◽  
Vol 12 (1) ◽  
pp. 202
Author(s):  
Salvatore Benfratello ◽  
Luigi Palizzolo ◽  
Santo Vazzano
Keyword(s):  
Optimal Design ◽  
Cross Section ◽  
Design Problem ◽  
Local Buckling ◽  
Plastic Behavior ◽  
Interior Point Algorithm ◽  
Great Reliability ◽  
Moment Resisting ◽  
Equivalent Bending Stiffness ◽  
The One

In the present paper an improved formulation devoted to the optimal design problem of a special moment resisting connection device for steel frames is proposed. This innovative device is called a Limited Resistance Plastic Device (LRPD) and it has been recently proposed and patented by some of the authors. It is thought to be preferably located at the extremes of the beam, connecting the beam end cross section with the relevant column. The typical device is a steel element characterized by symmetry with respect to three orthogonal barycentric planes and constituted by a sequence of three portions with abrupt cross section changes. The main novelty of the present proposal is related to the design of special geometry for the optimal device ensuring that it possesses a reduced resistance with respect to the relevant connected beam element, is characterized by an equivalent bending stiffness equal to the one of the connected beam elements and exhibits full plastic deformations avoiding any local instability phenomenon. The optimal design is formulated as a minimum volume one and is subjected to suitable constraints on the geometry of the device and on its elastic and plastic behavior. The optimization problem is a strongly non-linear programming one and it is solved by adopting an interior-point algorithm that is available in the MATLAB Optimization Toolbox. The numerical simulations are devoted to the most used standard steel profiles (IPE, HE) and the results prove the great reliability of the proposed device. In addition, the relevant elastic and plastic domains of the designed devices are defined, and the expected behavior of the device is verified by appropriate 3D finite element models in the ABAQUS environment.

scholarly journals On the Tidal Prism: The Roles of Basin Extension, Bottom Friction and Inlet Cross-Section

2021 ◽  
Vol 9 (1) ◽  
pp. 88
Author(s):  
Marco Petti ◽  
Sara Pascolo ◽  
Silvia Bosa ◽  
Nadia Busetto
Keyword(s):  
Cross Section ◽  
Bottom Friction ◽  
Static Method ◽  
Tidal Prism ◽  
Empirical Relationships ◽  
Cross Sectional ◽  
Asymptotic Regime ◽  
Static Regime ◽  
The One ◽  
Basin Area

The prism of the Lignano tidal inlet was approximately constant over the last forty years, although the section width has halved. This has led to questions concerning the factors that most influence the tidal prism, and on the applicability of the well-known A–P relationship. A conceptual scheme of the sea–channel–lagoon system has been used to perform a sensitivity analysis of different parameters that characterize both the basin and the inlet cross-section. A 2D hydrodynamic model has been applied to evaluate the prism and compare it to the one derived by a static method, which is the basis of the analytical derivation of the A–P linkage. Three regimes have been found in the prism variability as a function of the basin extension: a linear static regime between prism and basin area; an asymptotic regime in which the prism depends only on the basin bottom friction; and an intermediate one. In addition, the roles of the inlet and channel sizes on the prism value have been investigated. The results, compared to the empirical relationships between the prism and the inlet cross-section, show that a variation in the cross-sectional area does not always corresponds to a change in tidal prism.

scholarly journals Regularity results for an optimal design problem with a volume constraint

2014 ◽  
Vol 20 (2) ◽  
pp. 460-487 ◽  
Author(s):  
Menita Carozza ◽  
Irene Fonseca ◽  
Antonia Passarelli di Napoli
Keyword(s):  
Optimal Design ◽  
Design Problem ◽  
Volume Constraint ◽  
Optimal Design Problem ◽  
Regularity Results

Experimental Study on In-Plane Behavior of CFST Arch with New-Type Dumbbell-Shaped Section

2011 ◽  
Vol 255-260 ◽  
pp. 1198-1203 ◽  
Author(s):  
Ye Sheng
Keyword(s):  
Local Buckling ◽  
High Strength ◽  
Steel Tube ◽  
Calculation Model ◽  
Plastic Behavior ◽  
Loading Process ◽  
New Type ◽  
Set Up ◽  
Ultimate Load Carrying Capacity ◽  
Shaped Section

The weakness of traditional dumbbell-shaped section is that when concrete is filled into the web space, great stress is likely to produce cracks in the weld sealing between steel tube and web plates. In order to avoid this condition, a new-type dumbbell-shaped section is proposed. Experiments on concrete filled steel tubular (CFST) model arches with new-type dumbbell-shaped section have been carried out, concentrated loading at crown and L/4 section respectively. The result indicated that the new-type CFST arch has good elastic-plastic behavior and high strength, no local buckling appeared during the whole loading process, its in-plane mechanic behavior is similar with that of the CFST arch with single-tube. The dual nonlinear finite element calculation model is set up for the model arch, by means of this model the load-deflection curves during the loading process and the ultimate load-carrying capacity is analyzed.

scholarly journals Optimal design of a DC MHD pump by simulated annealing method

2014 ◽  
Vol 11 (2) ◽  
pp. 339-350
Author(s):  
Khadidja Bouali ◽  
Fatima Kadid ◽  
Rachid Abdessemed
Keyword(s):  
Simulated Annealing ◽  
Optimal Design ◽  
Objective Function ◽  
Design Problem ◽  
Design Methodology ◽  
Optimization Problem ◽  
Optimization Procedure ◽  
Simulated Annealing Method ◽  
Direct Interpretation ◽  
Annealing Method

In this paper a design methodology of a magnetohydrodynamic pump is proposed. The methodology is based on direct interpretation of the design problem as an optimization problem. The simulated annealing method is used for an optimal design of a DC MHD pump. The optimization procedure uses an objective function which can be the minimum of the mass. The constraints are both of geometrics and electromagnetic in type. The obtained results are reported.

scholarly journals Performances of moment resisting frames with slender composite sections in low-to-moderate seismic areas

2018 ◽  
Author(s):  
Hervé Degée ◽  
Yves Duchêne ◽  
Benno Hoffmeister
Keyword(s):  
Numerical Model ◽  
Global Analysis ◽  
Local Buckling ◽  
Experimental Tests ◽  
Hysteretic Behavior ◽  
Moderate Intensity ◽  
Moment Resisting Frames ◽  
Composite Frames ◽  
Moderate Seismicity ◽  
Moment Resisting

The aim of the recently completed European research program Meakado is therefore to study design options with requirements proportioned to the actual seismic context of constructions in areas characterized by a low or moderate seismic hazard, contrary to most researches aiming at maximizing the seismic performances. In this general framework, specific investigations have been carried out regarding typical beam profiles commonly used for multi-bay - multi-storey composite frames. In a first stage, experimental tests on class-3 composite beam-to-column connections were performed. The measurement results were evaluated with regard to the development of the hysteretic behavior with particular emphasis on the degradation. These test results have been used as reference for the calibration and validation of numerical model aiming at extending the scope of the experimental outcomes through appropriate parametric variations regarding the behavior of nodal connections as well as towards the global analysis and behavior of structures made of class 3 and 4 profiles. Numerical investigations of the global performance of composite frames with slender cross-sections are then performed resorting to the numerical model previously calibrated with respect to the experimental tests and additional simulations at node level. Results are compared to the performance of an equivalent frame made of compact steel profiles. Attention is paid to the effects of strength and stiffness degradation due to local buckling. The analysis of the results is specifically focusing on the comparison of the rotation capacity of the slender section with the actual rotation demand imposed by a moderate intensity earthquake. Based on the outcomes of these investigations, practical design recommendations are finally derived for multi-storey, multi-bay moment resisting frames with type b (full composite action) beam-to column connections located in low and moderate seismicity regions. 

INSTANTON-INDUCED CROSS-SECTION AT HIGH ENERGIES: LEADING ORDER AND BEYOND

1990 ◽  
Vol 05 (24) ◽  
pp. 1983-1991 ◽  
Author(s):  
S. YU. KHLEBNIKOV ◽  
V. A. RUBAKOV ◽  
P. G. TINYAKOV
Keyword(s):  
Total Cross Section ◽  
Explicit Form ◽  
Cross Section ◽  
High Energy ◽  
Electroweak Theory ◽  
Leading Order ◽  
Instanton Action ◽  
High Energies ◽  
High Energy Collisions ◽  
The One

We study the total cross-section of high energy collisions in the one-instanton sector of purely bosonic theories with instantons. We find that in the limit g2 → 0, E/E sph = fixed , the leading behavior of the total cross-section is σ lot ~ exp [1/g2(−2S0 + F(E/E sph ))], where S0 is the instanton action. In the electroweak theory at E/E sph ≪ 1, the function F(E/E sph ) is determined by the gauge boson part of the instanton configuration and its explicit form is found.

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