The structural member (beam, pipe, elbow, or truss) is kept straight and constrained, and it is moved to different positions and orientations in different steps; where appropriate, it is given a uniform velocity and acceleration. The structural member is subjected to various drag and buoyancy loads in the different steps. The problems are described in detail in the input files. The *DLOAD and *CLOAD options are tested in these problems. The effective axial force (output variable ESF1) for beam, pipe, and truss elements is also tested.

The features and load types tested in each problem in the various steps are:

The individual steps are named alphabetically as listed above. These names appear in the step headings.

Length	10
Orientation	45° with horizontal axis
Pipe section data	= 1.0, = 0.05

Aqua – environment:

Seabed elevation	0.0
Mean water elevation	40.0
Max. water elevation	40.0
Min. water elevation	40.0
Gravitational constant	32.2
Fluid mass density	1.987
Steady velocity specification: two-dimensional
(, elevation)	(2.0, 1.0, 0.0)
(, elevation)	(2.0, 1.0, 2000.0)
Steady velocity specification: three-dimensional
(, , elevation)	(2.0, 1.0, 0.0)
(, , elevation)	(2.0, 1.0, 2000.0)
( = 0.0)

The structural member is positioned vertically in both the two- and three-dimensional cases, such that one-half of the structure is below the seabed and only the top half is subject to fluid loads.

Nodes of each element are constrained to a single node whose reaction force is monitored.

The features and load types tested in each problem in the various steps are:

Height of the structure	2
Section data	= 1.0 for beams, = 1.0 for trusses

Aqua – environment:

Seabed elevation	0.0
Mean water elevation	2.0
Gravitational constant	32.2
Fluid mass density	1.99
Steady velocity specification: 2-D/3-D
(, , , elevation)	(1.0, 0.0, 0.0, 0.0)
(, , , elevation)	(1.0, 0.0, 0.0, 2.0)

Airy wave parameters:

A box composed of three-dimensional rigid elements is immersed in water subject to a buoyancy load (PB). The buoyancy forces and moments produced are measured by the reaction force at the rigid body reference node in four distinct configurations: in the initial configuration, as well as in the configurations produced when the body is given 60° of heel and then followed by 10° and 20° of trim.

Frequencies of natural vibration are computed for slender structures with different boundary conditions, with and without the effect of added mass.

Length	1000
Beam section data (circular)	= 3

Young's modulus	4.32 × 109
Density	= 14.91

Aqua – environment:

Vertical structural members, fully submerged and constrained, are subjected to a steady current velocity that is uniform with respect to elevation but varies with position (-coordinate for two-dimensional cases, and - and -coordinate for three-dimensional cases). The drag forces on the individual members can be determined analytically and compared to the nodal reaction forces.

The fluid velocity is equal to 2.8961.

Height of the structure	10
Pipe section data	= 1.0, = 0.05

Aqua – environment:

Steady velocity specification: two-dimensional case:

(, , , -coord.)	(, 0.0, 0.0, 100.0)
(, , , -coord.)	(, 0.0, 0.0, 300.0)
(, , , -coord.)	(, 0.0, 0.0, 600.0)
(, , , -coord.)	(, 0.0, 0.0, 900.0)

Steady velocity specification: three-dimensional case:

(, , , -coord., -coord.)	(, 0.0, 0.0, 100.0, 200.0)
(, , , -coord., -coord.)	(, 0.0, 0.0, 300.0, 200.0)
(, , , -coord., -coord.)	(, 0.0, 0.0, 600.0, 200.0)
(, , , -coord., -coord.)	(, 0.0, 0.0, 900.0, 200.0)
(, , , -coord., -coord.)	(, 0.0, 0.0, 100.0, 800.0)
(, , , -coord., -coord.)	(, 0.0, 0.0, 300.0, 800.0)
(, , , -coord., -coord.)	(, 0.0, 0.0, 600.0, 800.0)
(, , , -coord., -coord.)	(, 0.0, 0.0, 900.0, 800.0)

This problem tests the dynamic pressure implementation and closed-end buoyancy loading for the three ABAQUS/Aqua wave options. A vertical pile is fully constrained and subjected to buoyancy loading. The Airy, Stokes, and gridded wave options are used to calculate the total reaction force on the structure during a *DYNAMIC procedure. Distributed load type PB is used with a 50-element model, and concentrated load type TSB is used with a one-element model.

Height of the structure	175.0 (100.0 below and 75.0 above mean water elevation)
Pipe section data	= 1.0, = 0.25

Aqua – environment:

This problem illustrates the creation of the gridded wave file. The unformatted binary gridded wave files used in “Dynamic pressure, closed-end buoyancy loads” in “Aqua load cases,” Section 3.10.1” (ep32pxx3.inp and ep23pxx3.inp) are created from ASCII format files containing the gridded wave data using a FORTRAN program.

This problem tests the implementation of the effective axial force output quantity ESF1. Coincident, one-element, vertical piles are partially submerged in a Stokes wave field such that the element integration points change between unsubmerged and submerged conditions during the analysis. The piles are fully constrained and subjected to distributed load type PB including internal fluid pressure. One pile is completely filled with internal fluid (Case A), and one is partially filled with internal fluid such that the element integration point is above the internal fluid free surface elevation (Case B). To test the *AMPLITUDE option, an amplitude variation is added to the *DLOAD option in Cases A and B to produce, respectively, Cases C and D. Cases A and C use PIPE21 elements, and Cases B and D use B21 elements with *BEAM GENERAL SECTION to define the element properties. With the results from this analysis, the effective axial force output is tested using the *POST OUTPUT option.

This problem tests loading types PB and TSB when the fluid properties are prescribed as part of the loading. The *BEAM GENERAL SECTION option is used to describe the section properties.