Design and Overall Strength Analysis of Multi-Functional Elastic Connections Floating Breakwater System

As a new type of marine structure,floating breakwater can provide suitable water area for coastal residents.In this paper,a multi-module floating breakwater with three cylinders was designed.According to the characteristics of each module,the elastic connector was created.The cabins with functions such as living,generating electricity and entertainment were arranged.A linear spring constrained design wave(LSCDW)method for strength analysis of floating marine structures with multi-module elastic connections was proposed.The numerical model was verified by 1:50 similarity ratio in the test tank.According to the analysis of design wave and extreme wave conditions,considering the mooring loads and environmental loads and connector loads,the overall strength of breakwater was analyzed by LSCDW method.These studies can provide new insights and theoretical guidance for the design of multi-module floating structures.

A new approach for free vibration analysis of a system of elastically interconnected similar rectangular plates

A new procedure is proposed to ease the analyses of the free vibration of an elastically connected identical plates system with respect to Kirchhoff plate theory.A structure of n parallel,elastically connected rectangular plates is of concern,whereby the motion is explained by a set of n coupled partial differential equations.The method involves a new change in variables to uncouple equations and form an equal system of n decoupled plates,while each is assumed to be elastically connected to the ground.The differential quadrature method is adopted to solve the decoupled equations.To unravel the original system,the inverse transform is applied.Decoupling the equations enables one to solve them based on the solution methods available for a single plate system.This also diminishes the computational costs of such problems.By considering different boundary conditions,a case study is run to present the method and to validate the results with its counterparts,for which excellent agreement is observed.Assessing the influence of dimensionless thickness,aspect ratio,and stiffness coefficients on the frequencies reveals the different effects of them at the low order of dimensionless natural frequencies in comparison with high orders and for different boundary conditions.

Transversal vibrations of double-plate systems

This paper presents an analytical and numerical analysis of free and forced transversal vibrations of an elastically connected double-plate system. Analytical solutions of a system of coupled partial differential equations, which describe corresponding dynamical free and forced processes, are obtained using Bernoulli＇s particular integral and Lagrange＇s method of variation constants. It is shown that one-mode vibrations correspond to two-frequency regime for free vibrations induced by initial conditions and to three-frequency regime for forced vibrations induced by one-frequency external excitation and corresponding initial conditions. The analytical solutions show that the elastic connec- tion between plates leads to the appearance of twofrequency regime of time function, which corresponds to one eigenamplitude function of one mode, and also that the time functions of different vibration modes are uncoupled, for each shape of vibrations. It has been proven that for both elastically connected plates, for every pair of m and n, two possibilities for appearance of the resonance dynamical states, as well as for appearance of the dynamical absorption, are present. Using the MathCad program, the corresponding visualizations of the characteristic forms of the plate middle surfaces through time are presented.

Infl uence of structural parameters on dynamic characteristics and wind-induced buffeting responses of a super-long-span cable-stayed bridge

A 3D finite element （FE） model for the Sutong cable-stayed bridge （SCB） is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wind data, the measured spectra expression is presented using the nonlinear least-squares regression method. Turbulent winds at the bridge site are simulated based on the spectral representation method and the FFT technique. The influence of some key structural parameters and measures on the dynamic characteristics of the bridge are investigated. These parameters include dead load intensity, as well as vertical, lateral and torsional stiffness of the steel box girder. In addition, the influence of elastic stiffness of the connection device employed between the towers and the girder on the vibration mode of the steel box girder is investigated. The analysis shows that all of the vertical, lateral and torsional buffeting displacement responses reduce gradually as the dead load intensity increases. The dynamic characteristics and the structural buffeting displacement response of the SCB are only slightly affected by the vertical and torsional stiffness of the steel box girder, and the lateral and torsional buffeting displacement responses reduce gradually as the lateral stiffness increases. These results provide a reference for dynamic analysis and design of super-long-span cable-stayed bridges.

Influence of the connecting condition on the dynamic buckling of longitudinal impact for an elastic rod

The stress wave propagation law and dynamic buckling critical velocity are formulated and solved by considering a general axial connecting boundary for a slender elastic straight rod impacted by a rigid body. The influence of connecting stiffness on the critical velocity is investigated with varied impactor mass and buckling time. The influences of rod length and rod mass on the critical velocity are also discussed. It is found that greater connecting stiffness leads to larger stress amplitude, and further results in lower critical velocity. It is particularly noteworthy that when the connecting stiffness is less than a certain value, dynamic buckling only occurs before stress wave reflects off the connecting end. It is also shown that longer rod with larger slenderness ratio is easier to buckle, and the critical velocity for a larger-mass rod is higher than that for a lighter rod with the same geometry.