1	SACS Engineering Dynamics, Inc
2	Wave Load
3	Wave Load
4	Wave Load
5	Wave Load
6	Wave Load
7	Wave Load
8	Wave Load
9	Wave Load
10	Wave Load
11	Wave Load
12	Wave Load
13	Wave Load
14	Current Load
15	Wind Load Wind loads are calculated on all members above the mean water level as per API-RP2A guidelines. Typically a wind load for a 5-sec gust, is considered for global loading on the decks.
16	Wind Load Wind load criteria options available API ABS Australian criteria Cyclonic or Non-Cyclonic criteria
17	Wind Load API –RP2A 21^st Edition Criterion API-RP2A 20^th Edition Criterion Gust effects Included Gust effects not included
18	Wind Load API –RP2A 21^st Edition Criterion verses API-RP2A 20^th Edition Criterion
19	Wind Load ABS Criterion
20	Wind Load ABS 2000 Criterion
21	Wind Load Wind Load on Members
22	Wind Load Wind Load on Inclined Areas/Members
23	Wind Load Wind Areas Wind areas or are defined to account for the wind loading on un-modeled items such as derricks, buildings, mechanical equipment, flare booms, etc. A wind area is designated by a two character area identifier and consists of one or more surfaces defined using AREA input lines. The orientation of the surface is specified either by entering the projections of it on planes normal to the global axis or by specifying the area along with the azimuth and elevation angles.
24	Wind Load Wind Areas If more then one projected plane is specified for the same area identifier then the resultant area is used. It is recommended that if an object has projected areas in two or three planes that two separate wind areas be defined rather than specifying two projections together.
25	Wind Load Wind Areas The surface shape may be designated as flat or round together with a corresponding shape factor. The wind force components are calculated by multiplying the calculated wind pressure by the shape factor and the projected areas. The wind force is assumed to act at the specified centroid of the surface.
26	Wind Load Wind Areas The wind load is distributed over the specified number of joints. If more than one joint distribution is specified, the program assumes that these joints are connected to a rigid body to which the wind force is applied. The load is distributed to each joint by assuming the rigid body is supported at each joint by three translational and three rotational springs. The stiffness of the translational springs is unity while that of the rotational springs is 0.01 in the unit system the problem is defined. Wind Shield Zones By default, members located above the water surface receive wind loading. The program allows the specification of wind shield zones where members do not receive wind loading. Wind shield zones are defined by specifying the bottom and top elevation of the zone. Elevations are defined using global z elevation.
27	Special Elements SACS Special Elements : Wishbone Elements Gap Elements : Compression Only Element Tension Only Element No Load Element User defined Load Deflection Element Friction Element
28	Special Elements Wishbone Element: Wishbone Element is a factious element connecting two coincident joints used to model special boundary conditions between connecting structures.
29	Special Elements Compression only elements: Compression only element can be used to model supports during load out where loss of contact may occur between the structure and the support due to uneven fabrication yard surface or motion of barge. Initial gap spacing can also be defined on the MEMB2 input line.
30	Special Elements Tension only elements: Tension only elements/ Cable elements can be used to model slings for a lift analysis in conjunction with moment member end releases. Pre tension can be defined on the MEMB2 input line.
31	Special Elements No Load elements: No load elements can be used to model tie downs for the pre transportation analysis phase. The no load switch can then be turned off for the transportation analysis and the results from the two can then be combined directly. Same model can be used for both analysis. No load elements can also be used for loadout analysis to model loss of support.
32	Special Elements User defined load-deflection elements: User defined load deflection elements can be used to define non-linear load deflection characteristics. Many uses: Contact problems, suction pile behavior…etc
33	Special Elements
34	Special Elements
35	Special Elements
36	Post - Processing Member Design API-WSD API-LRFD Norsok Eurocode Danish British Canadian Linear Global (Section 17)
37	Post - Processing Element Code Check K-Factors / Effective Buckling Lengths K-factors or effective buckling length, but not both, may be specified for buckling about the local Y and Z axes. K-factors are specified on the pertinent GRUP line in columns but may be overridden on the MEMBER line in columns. When K-factors are used, the effective buckling length is calculated as the K-factor multiplied by the actual member length. When effective lengths are specified on the MEMBER line, then the effective buckling length is determined by multiplying the K factor from the GRUP line with the effective length value on the MEMBER line.
38	Post - Processing Element Code Check X Brace K-Factors For X bracing the K factor for compression elements is 0.9 when one pair of members framing into the joint must be in tension if the joint is not braced out of plane.
39	Post - Processing Element Code Check K Brace K-Factors For K bracing the K factor for compression elements is 0.8 when one pair of members framing into the joint must be in tension if the joint is not braced out of plane.
40	Post - Processing Element Code Check Reduction Factor Cm Cm can be based upon a constant value of 0.85, based upon end moments or axial load calculations or set to 1.0. The various options are defined on the GRUP line on column 47. Alternatively enter ‘M’ in column 34 of the OPTIONS line to exclude the value of the reduction factor Cm for combined axial compression and bending unity check, or enter ‘C’ to globally set the value of Cb to 1.0
41	Post - Processing Element Code Check Cb The value for Cb for members with Compact or Non-compact Sections with Unbraced length greater than Lb can be taken as 1.0 (default) or based upon end moment calculations as shown below by entering B in column 33 of the OPTIONS line.
42	Post - Processing Joint Can API RP2A 21^st Edition Supplement 2 guidelines implemented. Joints checked against API specified validity ranges. Where validity ranges have been infringed, Joint Can will report the lesser capacity based upon actual geometry or the limiting dimension.
43	Post - Processing Joint Can Basic Capacity of joints without overlap is given by:
44	Post - Processing Joint Can Chord Load Factor Q_f
45	Post - Processing Joint Can Joints with Thickened Cans
46	Post - Processing Joint Can Strength Check Interaction Ratio
47	Post - Processing Joint Can
48	Post - Processing Joint Can
49	PSI - Capabilities Foundations can be modeled using two approaches: (1) Adhesion (API + User defined) (2) P-Y, T-Z data (API + User defined) Adhesion – Linear (surface friction) P-Y, T-Z – Nonlinear load deflection curves. .
50	PSI - Capabilities Piles can be modeled as tubular or H sections. P-d Effects accounted for. Finite Difference approach used Mudslide condition simulation capabilities. Creates equivalent linearzied foundation super-elements to be used by dynamic analyses in lieu of pile stubs. Creates foundation solution file containing pile stresses to be used for fatigue analysis.
51	PSI - Capabilities The Pile and Pile3D programs, which are sub-programs of PSI, may be executed alone to calculate the behavior of a single pile. In addition to the features outlined above, the Pile program has the following features: Determines an equivalent pile stub that yields the same deflections and rotations as the soil/pile system.
52	PSI - Modeling Pile head Joint The interface joints between the linear structure and the nonlinear foundation must be designated in the SACS model by specifying the support condition ‘PILEHD’ on the appropriate JOINT input line. NOTE: The ‘PILEHD’ support condition represents fully fixed condition in lieu of a PSI analysis. Pile Local Coordinate System The pile default local coordinate system is defined with the local X axis pointing upward from the pile head joint along the pile axis defined by the pile batter joint or batter coordinates. By default, the local Y and Z axis orientations are load case dependent. For each load case, the local Y axis is automatically oriented such that it coincides with the direction of maximum pilehead deflection. The orientation of the local Y and Z axes may be overridden by the user by specifying the rotation angle about the local X axis in columns 51-56 on the PILE line
53	PSI - Modeling Specifying Elevations for Soil Resistance Curves Within a soil stratum, the PSI program connects the input P-Y or T-Z points with straight lines to fully define the pile/soil interaction curve for arbitrary displacements in that stratum. At depths between specified soil strata, PSI has the ability to linearly interpolate between curves or to use a constant T-Z curve. Interpolation between different strata may be achieved by omitting the bottom of strata location.
54	PSI Solution Procedure (P-Y, T-Z)
55	PSI Solution Process
56	Solution Objectives
57	Stiffness Table Approximation Approximate model of the pile head behavior Pile head forces are sampled for a range of points Linear interpolation between the points Reduction of computation time Improved chance of solution for highly non-linear problems Automatically generated (internal) … OR … User-specified with the TABR line
58	TABR lines
59	User-specified TABR lines PSI Listing File Cut and paste into PSI Input File Manually refine using Datagen Single Pile Analyses (Pile, Pile3D) Generate SPA Data Additional refinement as needed
60	PSI Convergence Tolerances
61	Convergence Report ITERATION DATA FOR LOAD CASE XXXX ITERATION RMS DEFLECTION RMS ROTATION 1 0.039673 0.000027 2 0.001083 0.000003 3 0.000070 0.000000 MAXIMUM PILEHEAD FORCE DIFFERENCE= 7.53085 % 4 0.022679 0.000026 MAXIMUM PILEHEAD FORCE DIFFERENCE= 7.67680 % 5 0.000626 0.000001 MAXIMUM PILEHEAD FORCE DIFFERENCE= 0.35047 %
62	Trouble Shooting – A checklist Review convergence report If necessary, use TABR lines Check tolerances and controls Review soil data Investigate each pile using Single Pile Analysis Fully constrain the pile heads and run SACS
63	Future Developments Shallow Foundations Spud-can Foundations Soil Plasticity Models (Collapse only) API RP 2A-WSD /21 Supplement 3 CPT Methods (loose soils, dense silt) Scour Depth Guidelines
64	Solution Objectives (lateral)
65	PSI/Pile Module
66	Grouted Joints – Joint Can
67	Grouted Joints – Joint Can/Fatigue
68	Grouted Joints – Joint Can/Fatigue
69	Grouted Joints – Joint Can/Fatigue
70	Grouted Joints – Fatigue
71	Ring Stiffened Joints – Fatigue
72	Modal Extraction : DYNPAC Some of the main features and capabilities of the DYNPAC MODULE are: Determines Natural Frequencies and modes of vibration. Accounts for structural mass and fluid added mass automatically Supports lumped or consistent mass generation Determines modal mass participation to allow determination of number of modes required for subsequent forced dynamic analysis.
73	Modal Extraction : DYNPAC Analysis Procedure: Linearize Foundation (Pile Superelement) - identify load cases for pile linearization, load cases dependent upon type of analysis. - include dead load - run PSI to generate Pile superelement. Modal Analysis - specify retained degrees of freedom. - Identify load cases to be converted to mass. - check cumulative mass participation factors. - check natural frequency and period (dynamic response low if period less that 2 seconds)
74	Load Path Dependent SCF’s For any tubular connection, all braces that lie in a plane with the Chord or within 15 degrees of that plane are considered in the calculation of load path SCF’s The chord member is selected on the following hierarchy: 1. Largest diameter 2. Largest wall thickness 3. Highest Yield stress 4. Members that are in-line with a 5 degree tolerance
75	Load Path Dependent SCF’s Joint Classification KT-connection: Axial load in middle brace opposes axial load from outside brace. For a KT connection the load to be transferred is taken as the smallest value of: 1) Center brace axial load 2) Twice the axial load component normal to the chord. The KT percentage for each brace is ratio of the transferred KT normal axial load component and the original axial load value. The remaining axial loads are then considered for K joint load transfer.
76	Load Path Dependent SCF’s Joint Classification For a K joint the axial load component normal to the chord is balanced by the axial load component normal to the chord in other braces (on the same side of the chord). The brace with the smallest normal axial load component is considered first with the brace containing the largest opposing normal axial load component. The balanced load is subtracted from the opposing brace and the process is repeated until all K joints are identified. Any X joint load paths are considered next for braces on opposite sides of the chord. The largest opposing normal axial force is considered first. The balanced load is subtracted from opposing brace and the process is repeated until all X joints are identified. Braces with remaining unbalanced axial loads are treated T/Y joints.
77	Load Path Dependent SCF’s SCF Determination The load path dependent SCF is calculated as a weighted average of the applicable KT, K, X and TY joints as: SCF = R_KTSCF_KT+ R_KSCF_K + R_XSCF_X + R_TYSCF_TY where R_KT, R_K , R_X , and R_TY are the ratios of each type of joint action.
78	Importing FE Joint Mesh Joint Meshing Two approaches are available for importing meshed joints into a SACS ‘stick’ model. 1. FEMGV Precede can generate a FEMGV batch file once a joint has been isolated by inserting a joint on the braces and chord members to define the portion of the joint that needs to be meshed. Precede will require the joint name, the number of elements around the circumference of a brace with the smallest diameter and also the element type. The batch file can then be subsequently read into FEMGV and the mesh is generated automatically. FEMGV can generate a FEMGV neutral file which can be read back into Precede and the mesh can be incorperated into the rest of the model by tools provided in Precede.
79	Importing FE Joint Mesh Joint Meshing (Continued) 2. SACS Mesh Joint Utility Very simple to use. Provide joint name to mesh, the mesh intensity ( limits 0.5 – 2, mesh intensity 1 = approx 28 nodes around the circumference of the smallest brace) and the model file name. The mesh utility will automatically mesh the joint and output a OCI file containing the ‘stick’ model with the joint mesh incorporated. FEMGV - Mesh Joint Utility FEMGV allows the user to control the length of brace/chord to be meshed. Also gives choice of element types. Cannot mesh joints with overlapped braces. Mesh Joint Utility allows the meshing of overlapped joints. No user control over the length of brace/chord member to be meshed. Meshing restricted to triangular palte elements (this is not a disadvantage).
80	Fatigue Analysis Fatigue analysis is required due to the cyclic loading imposed on the Jacket tubular joints by wave loads. Fatigue analysis could be of two types: Deterministic Fatigue Spectral Dynamic Fatigue
81	Fatigue Analysis In Deterministic Fatigue, discrete number of waves are used to characterize the total fatigue environment Partial Damage from the sea state = Damage is accumulated over all sea states (Miners Law): Deterministic analysis has been done for many years and has proven to be a reliable approach for dynamically insensitive structures, and for situations where all fatigue waves are of sufficiently long wave periods to avoid peaks and valleys of the structures transfer function. Very sensitive to the waves chosen for the analysis
82	Fatigue Analysis The spectral fatigue approach utilizes wave spectra and transfer functions, thus allowing the relationship of the ratio of structural response to wave height as a function of wave frequency to be developed for the wave frequency range. Therefore spectral fatigue accounts for the actual distribution of energy over the entire wave frequency range. In Dynamic Spectral Fatigue , Spectrum used to define the fatigue environment are: JONSWAP Ochi-Hubble Pierson-Moskowitz These Spectra are in-built in SACS
83	Fatigue Analysis Fatigue program features are as below Includes a wide range Stress Concentration Factor (SCF) theories and allows user defined input. Automatic redesign of chords or braces may be done to determine required joint can or brace stub thickness API, AWS and NPD fatigue failure (S-N) curves are built into the program. Also allows user defined input.
84	Dynamic Spectral Fatigue Analysis Procedure: Linearize Foundation -choose load cases for developing foundation superelement Modal Analysis to generate mass and mode files - check cumulative mass participation factors Run Wave Response to generate Transfer Function for each direction. - use waves of constant steepness to generate transfer function. - avoid waves under 1 foot ( 30cm ) - check transfer function for overturning moment and base shear. - solve for equivalent static loads. Run Fatigue - choose appropriate spectrum - choose S-N and SCF options
85	Earthquake Analysis
86	Earthquake Analysis
87	Earthquake Analysis
88	Earthquake Analysis
89	Earthquake Analysis
90	Earthquake Analysis
91	Earthquake Analysis
92	Earthquake Analysis
93	Earthquake Analysis
94	Earthquake Analysis
95	Earthquake Analysis
96	Spectral Wind Fatigue
97	Spectral Wind Fatigue
98	Spectral Wind Fatigue
99	Spectral Wind Fatigue
100	Non-Linear Analysis : Collapse Salient Features of Collapse Module are Linear and non-linear material behavior Includes member Global / Local buckling including 8 or more hinge points per member Includes tubular joint flexibility, joint plasticity and joint failure due to excessive strain Includes strain hardening and residual stress Creates analysis results file which is read by Collapse View Program which shows failure progression and the gradual plastification and collapse mechanism graphically
101	Pushover Analysis Pushover Analysis conducted to determine the reserve strength ratio of a jacket structure. Loading applied to the structure in sequence. Apply all gravity loads first. Apply environmental storm loading. Increase magnitude of environmental loading until the structure fails. RSR = Base Shear at 100% storm Load Base Shear at Failure Other approaches define failure with 100, 500, 1000, 5000,…year storms First Failure
102	Ship Impact Analysis (Static)
103	Dynamic Response
104	Dynamic Response
105	Dynamic Response
106	Dynamic Response
107	Dynamic Response
108	Dynamic Response
109	Dynamic Response
110	Dynamic Response
111	Dynamic Response
112	Dynamic Response
113	SACS