FloaTEC LLC

Houston, TX, United States

FloaTEC LLC

Houston, TX, United States
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Jin J.,Texas A&M University at Galveston | Meng B.,FloaTEC LLC
Ocean Engineering | Year: 2011

Recent hurricanes have caused severe structural damages to a number of coastal highway bridges along the US coast of the Gulf of Mexico. A large amount of bridge superstructure sections were displaced or pushed off the substructure by storm surge and wave action. To prevent such structural failure of coastal bridges, wave loads on bridge superstructures need to be quantified. In this study, two different numerical models were used to analyze wave-structure interaction and compute wave loads. Computational Fluid Dynamics (CFD) Software Flow-3D was used to analyze the effects of green water loading and superstructure elevation on wave forces. A 2D potential flow model was developed for computation of wave loads on bridge superstructures fully submerged in water. Wave induced pressure on bridge superstructures was obtained by solving complex velocity potential from Laplaces equation and boundary conditions using finite difference method. The 2D potential flow model was validated by large-scale laboratory measurements, and then used to perform parametric study using a range of wave parameters, water depth and bridge superstructure width. Equations for calculating wave loads on bridge superstructures were developed using results of the parametric study. © 2011 Elsevier Ltd. All rights reserved.


Chen B.,FloaTEC LLC | Nagarajaiah S.,Rice University
Structural Control and Health Monitoring | Year: 2013

The observer-based fault detection and isolation filter design method is a model-based method. By carefully choosing the observer gain, the residual outputs can be projected onto different independent subspaces. Each subspace corresponds to each monitored structural element, so that the projected residual will be nonzero when the associated structural element is damaged and zero when there is no damage. The key point of detection filter design is how to find an appropriate observer gain. This problem can be interpreted in a geometric framework and is found to be equivalent to the problem of finding a decentralized static output feedback gain. But it is a challenging task to find the decentralized controller by either analytical or numerical methods because its solution set is generally non-convex. In this paper, genetic algorithm is originally proposed to find the detection-filter-based decentralized controller, which can be applied in structural health monitoring. The numerical simulation and experimental results show that the developed method can successfully identify structural damage. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.


Yang C.K.,FloaTEC LLC | Kim M.H.,Texas A&M University
Ocean Engineering | Year: 2010

This paper deals with a numerical study of the transient effect of tendon disconnection on global performance of an extended tension leg platform (ETLP) during harsh environmental conditions of Gulf of Mexico (GoM). The ETLP has twelve tendons with twelve production top-tensioned risers (TTRs) and one drilling riser. The risers are attached by hydro-pneumatic tensioners. A time-domain nonlinear global-motion-analysis program for floating hulls coupled with risers/mooring lines is developed to model the transient effects associated with tendon disconnection at the top or the bottom. The sudden disconnection of one or more tendons causes the change of stiffness and natural periods, the imbalance of forces and moments of the total system, and possibly large transient overshoots in tension at the moment of disconnection. The breakage at the top and the unlatch at the bottom also make different impacts on the system. The transient responses and tensions are compared and discussed in the viewpoint of the robustness of the system. The survivability of a TLP with the loss of one or two tendons by accident during a lesser-than-extreme environment can also be checked by this kind of time-domain simulation technique.


Patent
FloaTEC LLC | Date: 2010-06-02

A riser disconnect and support mechanism for flexible risers and umbilicals on an offshore structure with low under keel clearance. A main body portion includes an inverted and truncated conical or convex section substantially at the center of the main body portion. The main body portion and conical section receive risers therethrough by means of a plurality of conduits through the main body portion and conical section. A plurality of projections extend radially outward from the main body portion. A plurality of arch-shaped riser supports are provided on each projection to support risers and/or umbilical lines and control their bending radii. The projections extend out from the main body portion at a distance that allows the portions of the risers below the main body portion to hang at an angle and bend radius in accordance with the design tolerances of the risers to prevent buckling or damage due to excessive bending while keeping the risers from contacting the sea floor.


Patent
FloaTEC LLC | Date: 2013-01-30

A mooring disconnect arrangement (10) for a floating offshore structure (16) and a mooring buoy (18). At least one high pressure water jet (12) is positioned to direct water between the floating offshore structure and the mooring buoy. The floating offshore structure and mooring buoy are also provided with specially shaped complementary surfaces (22, 24) to assist in disconnection and separation. One or more mechanical restraining devices (20) may be used to retain the floating offshore structure and mooring buoy connected together during normal drilling or production operations.


Patent
Floatec LLC | Date: 2013-07-11

A TLP design with improved motion characteristics and that is drawn to a means of reducing the required tendon stiffness and thereby reducing the overall cost of deepwater TLPs. The invention reduces the hydrodynamic added mass of the TLP hull. The horizontal pontoons that connect the vertical columns of the TLP are shaped to reduce the hydrodynamic added mass of the structure in the vertical direction.


Patent
FloaTEC LLC | Date: 2011-11-23

A spar hull centerwell arrangement wherein an adjustable buoyancy centerwell device (ABCD) is disposed within the centerwell of the structure. The adjustable buoyancy centerwell device is rigidly connected to the interior walls of the hard tank and defines an adjustable buoyancy centerwell device within the centerwell. The adjustable variable buoyancy unit is a water and airtight buoyancy chamber that allows the interior ballast to be changed as required. This device can also be used as a storage unit for on board fluids and other produced hydrocarbons.


Patent
FloaTEC LLC | Date: 2016-05-06

A semi-submersible structure with buoyant vertical columns and a buoyant pontoon. Unlike the typical semi-submersible where the pontoons are attached directly between the columns, the pontoon of the invention encircles the columns and is arranged outside of the columns. The pontoon encircling the columns simplifies construction and attachment of the pontoon and columns and improves the heave characteristics of the structure.


Patent
Floatec LLC | Date: 2014-04-17

A semi-submersible structure with buoyant vertical columns and a buoyant pontoon. Unlike the typical semi-submersible where the pontoons are attached directly between the columns, the pontoon of the invention encircles the columns and is arranged outside of the columns. The pontoon encircling the columns simplifies construction and attachment of the pontoon and columns and improves the heave characteristics of the structure.


Patent
FloaTEC LLC | Date: 2011-09-14

A truss type spar (10) that eliminates the need for the more complex and critical attachment of the buoyant hull to the truss section at a fabrication site/yard that is remote from the fabrication yard where the buoyant hull and truss sections were originally built. The buoyant hull (12) and initial truss sections (14) are constructed at the fabrication yard of choice, joined together, and transported to a dock or fabrication yard (a second location) that is as close as possible to the final offshore installation site. Transport of such completed structures, either separately or together, is normally done on a heavy lift vessel to reduce transport time and prevent damage to the buoyant hull and truss sections. Once at the fabrication yard/dock, the joined buoyant hull (12) and initial truss section (14) are floated off the heavy lift vessel and the draft adjusted to a position suitable for joining additional truss sections. One or more additional truss sections (16,18) can be attached to the initial section, and the completed buoyant hull and truss is then towed to the final offshore installation site.

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