Optimal Design of Semisubmersible Form by Minimizing its Motion in Random Seas

1984 ◽  
Vol 106 (1) ◽  
pp. 23-30 ◽  
Author(s):  
S. Akagi ◽  
K. Ito
Keyword(s):  
Optimal Design ◽  
Numerical Study ◽  
Design Method ◽  
A Priori ◽  
Working Environment ◽  
Programming Technique ◽  
Random Seas ◽  
Optimal Design Method ◽  
Heave Motion ◽  
Sea Wave

For the purpose of improving the utilization of semisubmersibles such as oil rigs in random seas, an optimal design method is proposed to seek optimal forms with minimum motion against sea wave. In the optimal design method proposed here, the design objective is chosen to minimize the variance of heave motion amplitude of a semisubmersible oscillated by the sea wave in a working environment. By giving the displacement and the hull length of the semisubmersible as design conditions a priori, diameters of both hulls and each columns are determined optimally by using the quadratic programming technique. Through a numerical study on a semisubmersible design problem, it is ascertained that by the optimal design method a considerable improvement of the motion performance can be attained compared with the result given by the conventional design method.

scholarly journals Development of Optimal Design Method for Steel Double-Beam Floor System Considering Rotational Constraints

2021 ◽  
Vol 11 (7) ◽  
pp. 3266
Author(s):  
Insub Choi ◽  
Dongwon Kim ◽  
Junhee Kim
Keyword(s):  
Optimal Design ◽  
Design Process ◽  
Design Method ◽  
Steel Beams ◽  
High Gravity ◽  
Double Beam ◽  
Iterative Analysis ◽  
Floor Systems ◽  
Optimal Design Method ◽  
Floor System

Under high gravity loads, steel double-beam floor systems need to be reinforced by beam-end concrete panels to reduce the material quantity since rotational constraints from the concrete panel can decrease the moment demand by inducing a negative moment at the ends of the beams. However, the optimal design process for the material quantity of steel beams requires a time-consuming iterative analysis for the entire floor system while especially keeping in consideration the rotational constraints in composite connections between the concrete panel and steel beams. This study aimed to develop an optimal design method with the LM (Length-Moment) index for the steel double-beam floor system to minimize material quantity without the iterative design process. The LM index is an indicator that can select a minimum cross-section of the steel beams in consideration of the flexural strength by lateral-torsional buckling. To verify the proposed design method, the material quantities between the proposed and code-based design methods were compared at various gravity loads. The proposed design method successfully optimized the material quantity of the steel double-beam floor systems without the iterative analysis by simply choosing the LM index of the steel beams that can minimize objective function while satisfying the safety-related constraint conditions. In particular, under the high gravity loads, the proposed design method was superb at providing a quantity-optimized design option. Thus, the proposed optimal design method can be an alternative for designing the steel double-beam floor system.

A Displacement-Based Optimal Design Method of RC Frames Subjected to Minor Earthquakes

2012 ◽  
Vol 594-597 ◽  
pp. 795-799
Author(s):  
Gui Tao Chen ◽  
De Min Wei
Keyword(s):  
Optimal Design ◽  
Optimization Design ◽  
Virtual Work ◽  
Design Method ◽  
Horizontal Displacement ◽  
Target Displacement ◽  
Programming Technique ◽  
Direct Displacement Based Design ◽  
Rc Frames ◽  
Displacement Based

A displacement-based optimization design method of RC structure was proposed by combining direct displacement-based design method with nonlinear programming technique. To avert the influence of target displacement, the stationary constraint displacement was presented, and the target displacement can be updated during the optimal design process. Principle of virtual work and Gaussian integral method was employed to simplify the explicit relationship between horizontal displacement and the section dimension. Comparison analysis of the local optimal results corresponding to different displacement shapes was conducted to achieve global optimal design. The numerical tests presented demonstrate the computational advantages of the discussed methods and suggesting that the proposed method is a reliably and efficiently tool for displacement-based optimal design.

scholarly journals D-Optimal Design for Information Driven Identification of Static Nonlinear Elements

2021 ◽  
Author(s):  
Nalika Ulapane ◽  
Karthick Thiyagarajan ◽  
sarath kodagoda ◽  
Linh Nguyen
Keyword(s):  
Optimal Design ◽  
Model Calibration ◽  
Design Method ◽  
Single Input Single Output ◽  
Single Output ◽  
Order Polynomial ◽  
Information Maximization ◽  
Pros And Cons ◽  
Single Input ◽  
Optimal Design Method

<div>Identification of static nonlinear elements (i.e., nonlinear elements whose outputs depend only on the present value of inputs) is crucial for the success of system identification tasks. Identification of static nonlinear elements though can pose several challenges. Two of the main challenges are: (1) mathematical models describing the elements being unknown and thus requiring black-box identification; and (2) collection of sufficiently informative measurements. With the aim of addressing the two challenges, we propose in this paper a method of predetermining informative measurement points offline (i.e., prior to conducting experiments or seeing any measured data), and using those measurements for online model calibration. Since we deal with an unknown model structure scenario, a high order polynomial model is assumed. Over fit and under fit avoidance are achieved via checking model convergence via an iterative means. Model dependent information maximization is done via a D-optimal design of experiments strategy. Due to experiments being designed offline and being designed prior to conducting measurements, this method eases off the computation burden at the point of conducting measurements. The need for in-the-loop information maximization while conducting measurements is avoided. We conclude by comparing the proposed D-optimal design method with a method of in-the-loop information maximization and point out the pros and cons. The method is demonstrated for the single-input-single-output (SISO) static nonlinear element case. The method can be extended to MISO systems as well.</div>

Sign in / Sign up

Export Citation Format

Share Document