The annulus between the pile and leg in jacket type offshore platforms may be filled with cement grout mainly to reduce horizontal deflections, inhibit corrosion, and increase the energy absorption capacity. This paper discusses an approach, which can be used to demonstrate an enhanced structural performance due to the both presence and lack of grouted piles. The compressive stress-strain response of the grout has been derived from the performed experiments. Having this response, the fiber beam column post-buckling element in the commercial code, DRAIN-3DX, was being used to investigate the behavior of grouted and ungrouted jackets and also the relative pile-leg interaction. It is therefore concluded that in the cases where the existing structure is ungrouted or incompletely grouted, adequate grouting can be considered as a relatively inexpensive method to improve the strength and performance of the structure. In fact, the cement filling of a tubular member increases its overall strength and also provides additional stability. The lateral force-deformation curves are equivalents for the cases where the axial force is less than 30% of the yielding force, Pyielding. However, as the axial force increases, the grouted portal element gradually gives a much better performance compared to the ungrouted element. By increasing the axial force, the lateral hysteretic behavior deteriorates in both grouted and ungrouted cases; however, this deterioration is more severe in the case of an ungrouted portal element.

1.
Zayas
,
V. A.
,
Mahin
,
S. A.
, and
Popov
,
E. P.
, 1980, “
Cyclic Inelastic Behavior of Steel Offshore Structures
,” Report No. UCB/EERC-80/27,
University of California
, Berkeley, CA.
2.
Asgarian
,
B.
,
Aghakouchak
,
A. A.
, and
Bea
,
R. G.
, 2005, “
Inelastic Post-Buckling and Cyclic Behavior of Tubular Braces
,”
J. Offshore Mech. Arct. Eng.
0892-7219,
127
, pp.
256
262
.
3.
Prakash
,
V.
,
Powell
,
G. H.
, and
Campbell
,
S.
, 1994, “
DRAIN-3DX Base Program Description and User Guide, Version 1.10
,” Report No. UCB/SEMM-94/07, Department of Civil Engineering,
University of California
, Berkeley, CA.
4.
Prakash
,
V.
, and
Powell
,
G. H.
, 1993, “
DRAIN-2DX, DRAIN-3DX and DRAINBUILDING: Base Program Design Documentation
,” Report No. UCB/SEMM-93/16, Department of Civil Engineering,
University of California
, Berkeley, CA.
5.
Zayas
,
V. A.
,
Shing
,
P. B.
,
Mahin
,
S. A.
, and
Popov
,
E. P.
, 1981, “
Inelastic Structural Modeling of Braced Offshore Platforms for Seismic Loading
,” Report No. UCB/EERC-81/04,
University of California
, Berkeley, CA.
6.
Kayvani
,
K.
, and
Barzegar
,
F.
, 1993, “
Modeling of Tubular Members in Offshore Steel Jacket Under Severe Cyclic Loading
,” Report No. R-324,
University of New South Wales
, Australia.
7.
Asgarian
,
B.
,
Aghakouchak
,
A. A.
, and
Bea
,
R. G.
, 2006, “
Nonlinear Analysis of Jacket-Type Offshore Platforms Using Fiber Elements
,”
J. Offshore Mech. Arct. Eng.
0892-7219,
128
, pp.
224
232
.
8.
Wimpey Offshore Engineers & Constructors Ltd.
, 1987, “
New Test Data on the Capacity of Cement-Filled Steel Tubulars
,” Paper No. OTC005484.
9.
Wimpey Laboratories Ltd.
, 1982, “
The Reappraisal of Steel Jacket Structures Allowing for the Composite Action of Grouted Piles
,” Paper No. OTC004194.
10.
Skallerud
,
B.
, and
Amdahl
,
J.
, 2002,
Nonlinear Analysis of Offshore Structures
,
Research Studies Press Ltd.
,
Baldock, Hertfordshire, England
.
11.
Higginbortham
,
A. B.
, 1973, “
The Inelastic Cyclic Behavior of Axially-Loaded Steel Members
,” disseration, University of Michigan, Ann Arbor, MI.
12.
Ikeda
,
K.
, and
Mahin
,
S. A.
, 1984, “
A Refined Physical Theory Model for Predicting the Seismic Behavior of Braced Steel Frames
,” Report No. UCB/EERC-84/12,
University of California
, Berkeley, CA.
13.
Maison
,
B.
, and
Popov
,
E. P.
, 1980, “
Cyclic Response Prediction for Braced Steel Frames
,”
ASCE J. Struct. Div.
0044-8001,
106
, pp.
1401
1406
.
14.
Marshal
,
P. W.
, 1978, “
Design Considerations for Offshore Structures Having Nonlinear Response to Earthquake
,”
ASCE Annual Convention and Exposition
,
Chicago, IL
.
15.
Sriregan
,
K.
, and
Marshal
,
P. W.
, 2000, “
Improved Marshal Strut Element to Predict the Ultimate Strength of Braced Tubular Steel Offshore Structures
,”
Proceeding of IMPLAST 2000
,
Melbourne, Australia
, Oct. 4–6.
16.
Powell
,
G. H.
, and
Campbell
,
S.
, 1994, “
DRAIN-3DX Element Description and User Guide for Element Type 01, Type 04, Type 05, Type 08, Type 09, Type 15, Type 17, Version 1.10
,” Report No. UCB/SEMM-94/08, Department of Civil Engineering,
University of California
, Berkeley, CA.
17.
Taucer
,
F.
,
Spacone
,
E.
, and
Fillipou
,
F. C.
, 1991, “
A Fiber Beam-Column Element for Seismic Response Analysis of Reinforced Concrete Structures
,” Report No. UCB/EERC-91/17, Earthquake Engineering Research Center,
University of California
, Berkeley, CA.
18.
Yang
,
Y. B.
, and
Kuo
,
S. R.
, 1994,
Theory and Analysis of Nonlinear Framed Structures
,
Prentice-Hall
,
Englewood Cliffs, NJ
.
19.
Amoco Production Co.
, 1983, “
Lateral Stability of Piles in Ungrouted Jacket Legs
,” Paper No. OTC004645.
20.
API
, 1993, “
Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms, Working Stress Design
,” Paper No. API(RP2A-WSD).
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