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Commissioned in 1914 as the most powerful weapon in the world, the Battleship TEXAS (BB-35) is the last surviving Dreadnought and the only battleship left in existence today, which fought in both World War I and World War II. Time and nature have taken a major structural toll on the ship; she is in immediate need of critical repairs, as well as a long-term solution for her continued preservation. Although a major shell restoration project was completed in 1990, the internal structure of the inner bottom has continued to deteriorate. In 2012, Texas Parks and Wildlife issued a Request for Proposals to solicit bids to perform an in-situ repair of the deteriorated frames, longitudinals, and inner-bottom plating. This phase of structural repairs is largely complete and has employed some novel techniques to restore the strength of the structural members while retaining as much of the historic fabric as possible. Additionally, the restoration presented an unusual scenario of needing to support the original triple expansion steam engines from overhead deck structure while renewing the foundation supports. This paper will describe the engine support system and the structural analysis used to design the system as well as details of the repair procedures to replacing or doubling the existing keel, longitudinals, and framing throughout the aft end of the ship
When we design a skyscraper, we expect it will perform to specification: that the tower will support so much weight and be able to withstand an earthquake of a certain strength. We play with different designs, tinker with different setups, but, until we take it out for a test run, we don't really know what it can do or where it will fail. This technology is the neural network, which underpins today's most advanced artificial intelligence systems. Increasingly, neural networks are moving into the core areas of society: They determine what we learn of the world through our social media feeds, they help doctors diagnose illnesses, and they even influence whether a person convicted of a crime will spend time in jail. Yet "the best approximation to what we know is that we know almost nothing about how neural networks actually work and what a really insightful theory would be," said Boris Hanin, a mathematician at Texas A&M University and a visiting scientist at Facebook AI Research who studies neural networks.
Arresting gear engines are large, heavy pieces of machinery which are costly to replace because of expensive repairs and modifications to existing decks. These costs can be avoided and the units installed in a more timely efficient manner if the photogrammetric process is used. This paper outlines the methods and techniques for using photogrammetry as a planning tool. It also demonstrates the practicality of collecting dimensional data from existing ship structures and foundations and using these data directly in the manufacturing phase of the equipment.
Subsea pipeline networks with components such as Wye-pieces and Pipeline End Manifolds (PLEMs) require protection from mechanical impacts. Pipeline scour is well understood and scour at solid caissons/gravity base foundations and piled foundations has been studied (Whitehouse, 1998; Whitehouse, et al., 2011; Sumer and Fredsøe, 2002). The scouring at small subsea gravity protection structures has received less attention than those with piles (Ottesen Hansen, 1997; Fog and Krogh, 2001) and hence there is uncertainty about predicting scour at such structures (Whitehouse, et al., 2010). The design of subsea structures requires a composite assessment of scour and stability for the protected asset and the protection structure itself. A closed structure may lead to the formation of a scour footprint that is quite similar to a solid caisson or gravity base. For an open structure, the contribution to scour interaction from the different components is more difficult to assess. Large-scale mobile bed laboratory experiments evaluated scour for a surface laid pipeline, with a spur and valves, and a generic subsea protection structure with mudmats and a perimeter skirt. Bathymetry mapping was achieved with a high precision underwater laser scanner. The experiments evaluated the contributions to scour arising from the different subsea components. Sediment mobility was a key factor, with the perimeter skirt able to resist scour over part of its length when the mobility was low/moderate, whereas in a high mobility environment the skirt was completely undermined. The foundation beams were underscoured quite quickly and the eroded sediment was flushed out through the perforated mudmats, highlighting the importance of mudmat design. The scour pattern and rate was similar with or without the pipeline in place. The underscouring of the beams caused settlement and tilting of the structure, highlighting the importance of assessing scour and scour countermeasures for these types of structure. The scour assessment needs to be integrated into the structural, geotechnical and functional performance study for any structure and the new results illustrate the importance of understanding effects related to sediment mobility, the prevailing direction of currents, the design of mudmats and skirts, and the need for additional scour countermeasures.
- Europe (0.48)
- North America > United States > Texas (0.28)
- Europe > Norway > North Sea > Danish Basin (0.89)
- Europe > Netherlands > German Basin (0.89)
- Europe > Germany > German Basin (0.89)
- (2 more...)
ABSTRACT: Semi-empirical methods are widely used in the seismic response analysis of pile foundations because the complexity of the problem precludes 3-D dynamic finite element analysis. The most common approach for the analysis of pile foundations is the use of nonlinear Winkler springs and dashpots to simulate the interaction between piles and soil. The properties of these springs are specified by p-y curves. The most widely used curves are those recommended by the American Petroleum Institute. In order to include the effects of inertial interaction with the superstructure, a very simplified foundation-superstructure model is employed in the analysis. This paper evaluates the effectiveness of p-y curves and the simplified foundationsuperstructure model in simulating the response of pile foundations. The p-y curve approach is shown to be potentially unreliable. The simplified model is shown to work very well provided the pile foundations undergo very little rotation of the pile cap and the pile foundation is analyzed using a simplified nonlinear continuum model of the soil-foundation system. INTRODUCTION Seismic soil-structure interaction analysis involving pile foundations is one of the more complex problems in geotechnical earthquake engineering. The analysis involves modelling pile-soil-pile interaction, the effects of the pile cap, nonlinear soil response and inertial interaction with the superstructure. Commercial structural analysis programs can not include the pile foundations directly. Therefore in the seismic analysis of bridges and buildings on pile foundations, various semi-empirical procedures are widely used. Dynamic nonlinear finite element analysis in the time domain using the full 3-dimensional wave equations is not feasible for engineering practice at present because of the time needed for the computations. However, by relaxing some of the boundary conditions associated with a full 3D analysis, it is possible to get reliable solutions for nonlinear response of pile foundations with greatly reduced computational effort.
- North America > United States > California (0.30)
- North America > Canada > British Columbia (0.28)