scholarly journals Experimental study on dynamic effect of freestanding tower of sea-crossing bridge under wave load

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhou Daocheng ◽  
Zhang Bo ◽  
Xue Sisi ◽  
Wei Chengxun ◽  
Ou Jinping
Keyword(s):  
Experimental Study ◽  
Dynamic Effect ◽  
Pile Group ◽  
Test Model ◽  
Wave Loads ◽  
Test Results ◽  
Base Shear ◽  
Wave Load ◽  
Vibration Period ◽  
Bridge Tower

AbstractThere is a debate over whether the sea-crossing bridges undergo dynamic motions when exposed to wave loads. In order to verify the dynamic effect of the tower of sea-crossing bridge under wave load, an experimental study on dynamic effect of a freestanding tower of sea-crossing bridge is accomplished in this paper. Firstly, a test model for a typical bridge tower of pile group foundation under wave load is established by using a scale of 1:100. Secondly, a typical sea condition is designed for the response test of the bridge tower under wave load. The test results indicated that obvious vibration of top the tower occurs when the wave load period is close to the natural vibration period of the structure, and both displacement and base shear are amplified. The results in this paper will provide an important reference for whether the dynamic effect of wave load should be considered in the designs of bridge structure under wave load.

Experimental Study on Wave Loads of Flooded Ship

2007 ◽  
Author(s):  
B. W. Kim ◽  
D. C. Hong ◽  
S. Y. Hong ◽  
J. H. Kyoung ◽  
S. K. Cho ◽  
...  
Keyword(s):  
Model Test ◽  
Ship Motions ◽  
Test Model ◽  
Bending Moments ◽  
Wave Loads ◽  
Test Results ◽  
Ocean Engineering ◽  
Shear Forces ◽  
Engineering Research ◽  
Ship Model

This paper investigates wave loads of a flooded ship by model test. Model tests are performed in ocean engineering basin of MOERI (Maritime and Ocean Engineering Research Institute). Ship motions are measured by RODYM6D. Wave loads such as shear forces, bending moments and torsion moments are measured by ATI load cell mounted on segmented parts of the ship model. A 300 m-long barge ship with two flooded compartments is considered in model test. Responses of intact and flooded cases are compared. The test results are also compared with numerical analyses using boundary element method.

Experimental study of wave loads on elevated pile cap of pile group foundation for sea-crossing bridges

2020 ◽  
Vol 197 ◽  
pp. 106896 ◽  
Author(s):  
Bo Xu ◽  
Kai Wei ◽  
Shunquan Qin ◽  
Jie Hong
Keyword(s):  
Experimental Study ◽  
Pile Group ◽  
Wave Loads ◽  
Pile Cap

Dynamic Analysis of a Jack-Up Rig, SDOF Approach: Design Consideration — I

2013 ◽  
Author(s):  
Francisco J. Godoy ◽  
Fernando Lorenzo
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Dynamic Effect ◽  
Wave Loads ◽  
Inertial Load ◽  
Base Shear ◽  
Oil Drilling ◽  
Analogy Method ◽  
Specific Assessment ◽  
Jack Up

A jack up rig, such as those used for oil drilling in the Gulf of Mexico, is a dynamic sensitive system subjected to random and periodic environmental loads (wave, wind, current, etc.), in which the inertia forces cannot be ignored. However, a static load analysis approach can be justified only if an extra inertial load set, due to the dynamic effect response, is included in the analysis. The Society of Naval Architects and Marine Engineers, SNAME T&R 5-5A, “Guidelines for Site Specific Assessment of Mobile Jack-Up Units”[1], addresses the calculation of the inertial load set by using the classical Single Degree of Freedom (SDOF) analogy to calculate such dynamic effect. This study evaluates how far apart crucial structural members’ stresses/loads obtained by using the SDOF analogy method are from those values obtained from a more realistic modal dynamic analysis. The analysis is performed for wave loads at different heights and frequencies such as those existing on extreme or severe design conditions as a storm. Although a jack up rig structure presents some non-linearities, especially in the legs-hull contact areas and the spud-cans interaction with the soil; a modal superposition analysis can be used if proper linearization is considered. The results of this study for a jack show that the SDOF analogy method tends to underestimate the base shear loads for high wave periods and conversely overestimate some stresses on crucial members, such as the legs’ chords close to the hull for all the wave periods. This study shows that the stresses on one of the legs’ chord of the most loaded leg, due to the dynamic effect produced by the harmonic loads calculated with the SDOF analogy developed in this study tend to be overestimated as the wave period decreases. Conversely, the calculation of the base shear of the structure employing a quasi-static analysis with inertial load set (ILS) as calculated in this study shows that the base shear forces difference between the modal dynamic analysis and the quasi static analysis tends to decrease as the periods of the wave decreases.

scholarly journals Mechanical Behavior of Buried Pipelines Subjected to Faults

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Xiaolong Wei ◽  
Wenshuai Jiao ◽  
Xi Zeng ◽  
Danfu Zhang ◽  
Guofeng Du
Keyword(s):  
Compressive Strain ◽  
Small Deformation ◽  
Dynamic Effect ◽  
Element Model ◽  
Test Model ◽  
Test Results ◽  
Buried Pipelines ◽  
Backfill Soil ◽  
Full Scale Tests ◽  
Lab Test

The length of buried pipelines usually extends thousands of meters or more in engineering, and it is difficult to carry out full-scale tests in the laboratory. Therefore, considering the seriousness of pipeline damage and the difficulty of operating tests and other test limitations, it is necessary to develop a reasonable method to simplify the length of the model for a practical lab test. In this research, an equivalent spring model was established to simulate the small deformation section of the pipeline far away from the fault and the effect of fault displacements, pipeline diameters, wall thicknesses, buried depths, soil materials, and spring constraints on the mechanical properties of pipelines was analyzed. Based on the finite element model using ABAQUS software, the results of the shell model with fixed boundary at both ends were compared; in addition, the dynamic effect of pipelines was investigated. The results show that the two-end spring device can better control the size of the test model and enhance the reliability of the test results. The vibration response of the pipeline mainly depends on the inconsistent movement of soil at both ends of the fault. The analysis results show that choosing a larger pipeline diameter, smaller buried depth, noncohesive backfill soil, and spring with a smaller elastic coefficient is beneficial to reduce pipeline strain and resist pipeline deformation. A simplified formula of the axial compressive strain of buried pipelines across oblique-slip fault is obtained.

Wave and wave-current actions on a bridge tower: An experimental study

2018 ◽  
Vol 22 (6) ◽  
pp. 1467-1478 ◽  
Author(s):  
Chengxun Wei ◽  
Daocheng Zhou ◽  
Jinping Ou
Keyword(s):  
Pile Group ◽  
Ocean Waves ◽  
Experimental Results ◽  
Dynamic Responses ◽  
Wave Forces ◽  
Base Shear ◽  
Shear Forces ◽  
Natural Period ◽  
Motion Responses ◽  
Bridge Tower

With a scale of 1:100, an experimental model was set up to investigate the dynamic responses of a bridge tower subjected to ocean waves and wave-currents. The bridge tower was designed for a sea-crossing bridge. Based on a pile-group foundation, it was designed to be a typical gate-type structure. Wave-induced base shear forces on the foundation and motion responses of the tower were measured and analyzed. The experimental results show that when a wave period is close to the natural period of the structure, an obvious resonance will be induced on the structure. For different wave action angles, the longitudinal incident waves induced the largest longitudinal base shear forces on the foundation and the greatest dynamic motions on the upper tower of the structure. Because of the pile-group effectiveness, the incident directions of the waves and the wave periods affect the acting forces on the foundation of the structure. For wave-current actions, forward currents increase the forward wave forces on the foundation and decrease the backward forces, but do not significantly affect the motion responses of the upper tower. The experimental results can be used as the verification data for numerical calculations. With the structural forms of the pile-group and the gate-type tower being typical, the results given in this study can be used as a reference for similar engineering designs.

Effect of Sacrificial Anodes on Wave Loads on Jacket Structure

2017 ◽  
Author(s):  
Kasthuri Nallayarasu ◽  
Panneer Selvam Rajamanickam
Keyword(s):  
Offshore Structures ◽  
Total Weight ◽  
Depth Range ◽  
Wave Loads ◽  
Base Shear ◽  
Wave Load ◽  
Theoretical Evaluation ◽  
Design Engineers ◽  
Jacket Structures ◽  
Order Of Magnitude

Wave and current loads on offshore structures are an important factor in the design of offshore structures. These forces are usually evaluated by semi-empirical Morison equation for tubular members wherein the ratio of characteristic dimension to wavelength is less than 0.2. In many cases, offshore structures such as jackets will have appurtenances such as anodes fitted on to them for various purposes, which may not contribute to the overall stiffness. However, these items will contribute to the wave and current loads in the order of magnitude of 10 to 20%. The calculation of hydrodynamic loads on such singular tubular members fitted with appurtenances can be done by taking to account their contribution towards drag and inertia. However, for complex structures, such as jacket structures with numerous members, it becomes practically very difficult and time consuming to do this calculation. In the industry, the general practice is to increase the overall loading due to presence of anodes by around 10 to 20%, based on experience and thumb rules. This paper focuses on the evaluation of wave loads on jackets due to the presence of anodes on jacket legs and braces, and comparing them to that of a jacket without anodes. The evaluation of wave loads is done by both numerical modelling and theoretical evaluation. The numerical model is based on frame analysis using SACS software which has the facility to simulate the wave load on space frame structures. Three different anode-to-jacket weight ratios (total weight of anode to total weight of jacket) are considered. The anodes are modelled as per design requirements and distributed throughout the structure. Recommended hydrodynamic coefficients from codal provisions are used. The overturning moments and base shear are evaluated for design regular waves and current. Results are presented in terms of comparison of base shear and overturning moment to ensure consistency, for three different cases. The recommendations for design engineers within the depth range and region studied can be drawn from this study.

Experimental study of breaking wave loads on elevated pile cap with rectangular cross-section

2021 ◽  
Vol 227 ◽  
pp. 108878
Author(s):  
Jie Hong ◽  
Kai Wei ◽  
Zhonghui Shen ◽  
Bo Xu ◽  
Shunquan Qin
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Breaking Wave ◽  
Wave Loads ◽  
Pile Cap

scholarly journals Experimental Study on Improvement of Marine Soft Soil with Alkali Residue

2018 ◽  
Vol 53 ◽  
pp. 04021
Author(s):  
SHAO Yong ◽  
LIU Xiao-li ◽  
ZHU Jin-jun
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Void Ratio ◽  
Soft Soil ◽  
Compressive Modulus ◽  
Engineering Properties ◽  
Test Results ◽  
Use Of Resources ◽  
One Year

Industrial alkali slag is the discharge waste in the process of alkali production. About one million tons of alkali slag is discharged in China in one year. It is a burden on the environment, whether it is directly stacked or discharged into the sea. If we can realize the use of resources, it is a multi-pronged move, so alkali slag is used to improve solidified marine soft soil in this paper. The test results show that the alkali residue can effectively improve the engineering properties of marine soft soil. Among them, the unconfined compressive strength and compressive modulus are increased by about 10 times, and the void ratio and plasticity index can all reach the level of general clay. It shows that alkali slag has the potential to improve marine soft soil and can be popularized in engineering.

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