Dynamic Behaviour of Minimum Platforms Under Random Seas

2003 ◽  
Author(s):  
Micaela Pilotto ◽  
Beverley F. Ronalds
Keyword(s):  
Dynamic Response ◽  
Dynamic Behaviour ◽  
Amplification Factor ◽  
Finite Element Models ◽  
Dynamic Amplification Factor ◽  
Maximum Value ◽  
Random Seas ◽  
Exponential Stretching ◽  
Structural Configurations ◽  
Dynamic Amplification

This paper describes the dynamic response of minimum facilities with different structural configurations which are subjected to random seas. The finite element models are kept simple with the aim of focusing on the physics of the phenomena involved. The response is studied in terms of the dynamic amplification factor (DAF), representing the ratio between the dynamic and the static response. Two different formulations of the DAF under random seas are compared. The first is defined in terms of standard deviation (DAF1), the second in terms of the most probable maximum value (DAF2). Ringing is observed to be a relevant feature of the dynamic response and to affect primarily the braced monopod configurations. Ringing is detected using DAF2. The paper also addresses the importance of the kinematic representation above the still water level. Different methods of stretching the velocity field in the wave zone (delta, Wheeler and exponential stretching) are shown to have a significant impact on the dynamic response of the platforms.

Dynamic Response of High Steep Rock Slopes Based on Wenchuan Near-Field Seismic Motion Characteristics

2010 ◽  
Vol 168-170 ◽  
pp. 1090-1097
Author(s):  
Shi Guo Xiao ◽  
Wen Kai Feng
Keyword(s):  
Numerical Analysis ◽  
Dynamic Response ◽  
Amplification Factor ◽  
Near Field ◽  
Seismic Load ◽  
Rock Slopes ◽  
Dynamic Amplification Factor ◽  
Seismic Motion ◽  
Dynamic Amplification ◽  
Motion Characteristics

Near-field seismic motion characteristics are analyzed in accordance with records of the 2008 Ms8.0 Wenchuan Earthquake measured at Wolong Station, upon which the determination of seismic load is introduced. Dynamic response features, such as acceleration, displacement and stress, of high steep rock slopes on the banks of Zipingpu Reservoir at a variety of locations resulting from horizontal seismic force are analyzed with a numerical analysis routine. The dynamic amplification factor on the slope top is determined, leading to a characterization of the mode of failure of the high steep slope. Analyses show that the dynamic amplification factor at the top of the slopes is about 1.34; however, dynamic response deformation features and stress state at different positions on the slope vary. Earthquake damage of the high steep rock slopes consists mainly of partial avalanche of the rock mass at the top of the slopes by joint cutting. Field investigations after the earthquake have partially confirmed the numerical analysis results presented in this paper.

scholarly journals Effect of temperature and porosities on dynamic response of functionally graded beams carrying a moving load

2017 ◽  
Vol 20 (K2) ◽  
pp. 24-33
Author(s):  
Tuyen Van Bui
Keyword(s):  
Dynamic Response ◽  
Temperature Rise ◽  
Material Properties ◽  
Amplification Factor ◽  
Moving Load ◽  
Functionally Graded ◽  
Effect Of Temperature ◽  
Element Formulation ◽  
Dynamic Amplification Factor ◽  
Dynamic Amplification

The effect of temperature and porosities on the dynamic response of functionally graded beams carrying a moving load is investigated. Uniform and nonlinear temperature distributions in the beam thickness are considered. The material properties are assumed to be temperature dependent and they are graded in the thickness direction by a power-law distribution. A modified rule of mixture, taking the porosities into consideration, is adopted to evaluate the effective material properties. Based on Euler-Bernoulli beam theory, equations of motion are derived and they are solved by a finite element formulation in combination with the Newmark method. Numerical results show that the dynamic amplification factor increases by the increase of the temperature rise and the porosity volume fraction. The increase of the dynamic amplification factor by the temperature rise is more significant by the uniform temperature rise and for the beam associated with a higher grading index.

scholarly journals Dynamic Response of Long Rectangular Floors Subjected to Periodic Force Excitation

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1417 ◽  
Author(s):  
Zsuzsa B. Pap ◽  
László P. Kollár
Keyword(s):  
Dynamic Response ◽  
Amplification Factor ◽  
Damping Ratio ◽  
Effective Width ◽  
Rectangular Plates ◽  
Dynamic Amplification Factor ◽  
Periodic Force ◽  
Static Loads ◽  
Dynamic Amplification ◽  
Force Excitation

Since damping in lightweight floors is usually low, dynamic amplification can be rather high. Long rectangular plates subjected to concentrated loads are often investigated by a replacement beam with a so called “effective width”. Although this approach is a reliable tool for static loads, the steady-state dynamic response of beams and long plates subjected to periodic loads are significantly different. The maximum displacements and accelerations of beams (and of not-long rectangular plates) are obtained by using a dynamic amplification factor, which in the case of resonance is equal to 1 / 2 ξ , where ξ is the damping ratio. For long plates (and for not-long orthotropic rib-stiffened plates), as discussed in the paper, the response and the amplification factor are substantially different from those of beams. Hence, design based on effective width may lead to 2–4 times higher acceleration than the real values. In an economic design, to avoid unnecessary damping enhancement, this effect must be taken into account.

Dynamic Response of Shallow Water Monopod Platforms

2002 ◽  
Author(s):  
Micaela Pilotto ◽  
Beverley F. Ronalds ◽  
Roman Stocker
Keyword(s):  
Dynamic Response ◽  
Shallow Water ◽  
Amplification Factor ◽  
Water Environment ◽  
Wave Theory ◽  
Wave Period ◽  
Dynamic Amplification Factor ◽  
Natural Period ◽  
Non Linear ◽  
Dynamic Amplification

This paper describes a systematic desktop study of the non-linear dynamic behavior of monopod platforms. The aim of this work is to highlight some important factors in the dynamics of minimum structures in shallow water. The analysis is performed in the time domain with regular wave loading. The non-linearities are due to the wave theory (Stream function of 8th order), to the shallow water environment and to the drag-dominated situation. Idealizations of two braced monopod configurations are compared with the simpler and more commonly studied unbraced monopod. Aspects highlighted for each configuration include the effect of wave period and top mass on the dynamic amplification factor. In particular, the analysis focuses on the highly non-linear behavior in the wave zone. The results show that braced monopods are dynamically more sensitive than unbraced monopods. In particular, braced monopods exhibit more energy at higher harmonics in the quasi-static response. This yields a consistently stronger dynamic response even if the wave period and the natural period of the structure are very different. The importance of the mass at the top of the structure in the dynamic response and in particular its role in increasing the dynamic amplification factor up the water column are highlighted.

ON THE MAXIMUM AMPLIFICATION FACTOR OF A MOVING POINT FORCE ON A SIMPLE BEAM

1992 ◽  
Vol 16 (1) ◽  
pp. 61-81 ◽  
Author(s):  
J.L. Urrutia-Galicia ◽  
A. Salazar-Hernández
Keyword(s):  
Dynamic Behaviour ◽  
Amplification Factor ◽  
Point Force ◽  
Dynamic Amplification Factor ◽  
Static Displacement ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Middle Cross Section ◽  
Dynamic Amplification ◽  
Maximum Amplification

The dynamic behaviour of a simply supported beam traversed at constant velocity by a point force is thoroughly reviewed. In this work it is shown that the maximum dynamic amplification factor of a simple beam under a travelling point force is 1.74 times the static displacement due to that point force statically applied at the middle cross section of any simply supported beam. Besides it is also shown that this maximum amplification factor of 1.74 occurs at x=0.53 times the length of the beam ℓ when the load has reached the point 0.76ℓ and it corresponds to a velocity of 0.625 times the currently termed “resonance” velocity.

Experimental study on the dynamic effects caused by vehicular traffic on a ferry boarding ramp

2002 ◽  
Vol 29 (1) ◽  
pp. 27-36
Author(s):  
Marc Savard ◽  
Marc-André Careau ◽  
Alain Drouin
Keyword(s):  
Dynamic Behaviour ◽  
Amplification Factor ◽  
Highway Bridges ◽  
Load Test ◽  
Heavy Vehicles ◽  
Dynamic Effects ◽  
Dynamic Amplification Factor ◽  
Dynamic Load Allowance ◽  
Factor Design ◽  
Dynamic Amplification

This article presents some of the results obtained during a load test conducted on a ferry boarding ramp operated by the Société des traversiers du Québec. The measurements highlight the sensitivity of these structures to the dynamic effects caused by two heavy vehicles. Since the dynamic behaviour of highway bridges is affected by parameters different from those that affect ferry boarding ramps, the article presents a reflection on the dynamic load allowance suitable for the evaluation or design of this latter type of structure.Key words: boarding ramp, bridge, dynamic amplification factor, design codes.

Analysis of test blanket module attachments under electromagnetic loads by using a dynamic amplification factor envelope

2018 ◽  
Vol 136 ◽  
pp. 1247-1251
Author(s):  
Raúl Muñoz ◽  
Francisco J. Calvo ◽  
Sergio Sádaba ◽  
Ana M. Gil ◽  
Javier Rodríguez ◽  
...  
Keyword(s):  
Amplification Factor ◽  
Dynamic Amplification Factor ◽  
Dynamic Amplification

scholarly journals A Study on Dynamic Amplification Factor and Structure Parameter of Bridge Deck Pavement Based on Bridge Deck Pavement Roughness

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Fei Han ◽  
Dan-hui Dan ◽  
Hu Wang
Keyword(s):  
Bridge Deck ◽  
Amplification Factor ◽  
Amplification Coefficient ◽  
Dynamic Amplification Factor ◽  
Vibration Load ◽  
Pavement Roughness ◽  
Composite Bridge ◽  
Dynamic Amplification ◽  
Cushion Layer ◽  
Bridge Deck Pavement

In order to study the coupled influence of deck pavement roughness and velocity on dynamic amplification factor, a 2-DOF 1/4 vehicle model is employed to establish the vehicle-bridge-coupled vibration system. The random dynamic load of running vehicle simulated by software MATLAB is applied on bridge deck pavement (BDP) through ANSYS software. Besides, the influence of BDP parameters on control stress under static load and random vibration load is analyzed. The results show that if the surface of BDP is smooth, the dynamic magnification coefficient would first increase and then decrease with increasing of vehicle velocity and reach its maximum value when v = 20 m/s; if the surface of BDP is rough, the maximal and minimum values of the dynamic amplification coefficient (DAC) occur, respectively, when the velocity reaches 10 m/s and 15 m/s. For a composite bridge deck with the cushion layer, the thickness of asphalt pavement should be not too thick or thin and better to be controlled for about 10 cm; with the increasing of cushion layer thickness, the control stress of deck pavement is all decreased and show similar change regularity under effect of different loads. In view of self-weight of structure, the thickness of the cushion layer is recommended to be controlled for about 4 cm.

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