This paper presents the failure pattern, the ultimate strength, and the stress concentration factor of unstiffened T-joints obtained from experimental and numerical investigations conducted on them under axial brace compression loading. The numerical modeling was performed on the whole joint using ANSYS software package. This modeling has predicted the ultimate strength accurately when compared with that of the conventional modeling of only a portion of the joint. The nominal diameter and thickness of the chord of the unstiffened T-joints were 324 mm and 12 mm, respectively, and the corresponding values of the brace were 219 mm and 8 mm, respectively. The T-joint was approximately one-fourth the size of the largest joints in the platforms built in a shallow water depth of 80 m in the Bombay High field. The bending of the whole chord member combined with punching shear failure due to its ovalization was observed to be the predominant behavior of the unstiffened joint. The numerical analysis has simulated the behavior of the joint as was observed in the experiment and has also helped establish its correct failure pattern. It was also observed in these investigations that the unstiffened joint was stiffer in ovalization mode than in flexural deflection. The results obtained from the numerical modeling were observed, in general, to be in good agreement with that obtained from the testing. The stress concentration factor predicted by the numerical analysis is in close agreement with that measured in the experiment as well as that computed using well established parametric equations.

1.
Clauss
,
G.
,
Lehmann
,
E.
, and
Ostergaad
,
C.
, 1994,
Offshore Structures: Conceptual Design and Hydrodynamics
,
Springer-Verlag
,
London
, p.
1
.
2.
Thandavamoorthy
,
T. S.
, 2002, “
Finite Element Modelling of the Behaviour of Internally Ring Stiffened T-Joint of Offshore Platform
,”
J. Institution of Engrs. (India)
,
83
, pp.
139
145
.
3.
Chen
,
W. F.
, and
Han
,
D. J.
, 1985,
Tubular Members in Offshore Structures
,
Pitman Advanced Publishing Program
,
Boston, MA
.
4.
Digre
,
K. A.
,
Krieger
,
W.
,
Wisch
,
D. J.
, and
Petrauskas
,
C.
, 1997, “
API RP 2A Draft Section 17 Assessment of Existing Platforms
,”
BOSS 94: Behaviour of Offshore Structures
,
C.
Chryssostomidis
,
Oxford
, pp.
467
478
.
5.
Thandavamoorthy
,
T. S.
, 2000, “
Investigations on Internally Ring Stiffened Steel Tubular Joints of Offshore Platforms
,”
ASME J. Offshore Mech. Arct. Eng.
0892-7219,
122
(
4
), pp.
233
242
.
6.
Marshall
,
P. W.
, 1992,
Design of Welded Tubular Connections
,
Elsevier Science Publishers
,
Amsterdam
.
7.
Puthli
,
R. S.
,
van Foeken
,
R. J.
, and
Romeijn
,
A.
, 1996, “
Guidelines on the Determination of Stress Concentration Factors of Circular and Rectangular Hollow Section Joints
,”
Fatigue in Offshore Structures
,
W. D.
Dover
and
A. G.
Madhava Rao
, eds.,
Oxford & IBH Publishing Co.
,
New Delhi
, Vol.
1
, pp.
129
153
.
8.
Nazari
,
A.
,
Guan
,
Z.
,
Daniel
,
W. J. T.
, and
Gurgenci
,
H.
, 2007, “
Parametric Study of Hot Spot Stresses Around Tubular Joints With Doubler Plates
,”
Pract. Period. Struct. Des. Constr.
1084-0680,
12
(
1
), pp.
38
47
.
9.
Straub
,
D.
, and
Faber
,
M. H.
, 2005, “
Risk Based Acceptance Criteria for Joints Subject to Fatigue Deterioration
,”
ASME J. Offshore Mech. Arct. Eng.
0892-7219,
127
, pp.
150
157
.
10.
Thandavamoorthy
,
T. S.
, 2005,
Analysis of Structures: Strength and Behaviour
,
Oxford University Press
,
New Delhi, India
.
11.
Ghanameh
,
M. F.
,
Thevenet
,
D.
, and
Zeghloul
,
A.
, 2005, “
Effect of Joint Configuration and Loading Type on Stress Concentration in Offshore Welded Tubular Joints
,”
Proceedings of APM 2005, Advanced Problems in Mechanics
, St. Petersburg, Jun. 28–Jul. 5, pp.
1
8
.
12.
Dutta
,
D.
, 1996, “
Parameters Influencing the Stress Concentration Factors in Joints in Offshore Structures
,”
Fatigue in Offshore Structures
,
W. D.
Dover
and
A. G.
Madhava Rao
, ed.,
Oxford & IBH Publishing Co.
,
New Delhi, India
, Vol.
1
, pp.
77
128
.
13.
UEG
, 1985, “
Design of Tubular Joints for Offshore Structures
,” Publication No. UR 33, Vol. 1, Underwater Engineering Group, London.
14.
UEG
, 1985, “
Design of Tubular Joints for Offshore Structures
,” Publication No. UR 33, Vol. 2, Underwater Engineering Group, London.
15.
UEG
, 1985, “
Design of Tubular Joints for Offshore Structures
,” Publication No. UR 33, Vol. 3, Underwater Engineering Group, London.
16.
1993, “
Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms-Load and Resistant Factor Design
,” API RP 2A-LRFD, American Petroleum Institute, Washington, DC.
17.
2007, “
Petroleum and Natural Gas Industries—Offshore Structures—Part 2: Fixed Steel Structures
,” ISO, 19902, Revised ISO 13819-2, London.
18.
Bhuyan
,
G. S.
,
Arockiasamy
,
M.
, and
Munaswamy
,
K.
, 1985, “
Analysis of Tubular Joint With Weld Toe Crack by Finite Element Methods
,”
Commun. Appl. Numer. Methods
0748-8025,
1
(
6
), pp.
325
331
.
19.
Hellier
,
A. K.
,
Connolly
,
M. P.
, and
Dover
,
W. D.
, 1990, “
Stress Concentration Factors for Tubular Y- and T-Joints
,”
Int. J. Fatigue
0142-1123,
12
(
1
), pp.
13
23
.
20.
Haswell
,
J.
, 1991, “
Simple Models for Predicting Stress Intensity Factors for Tubular Joints
,”
Fatigue Fract. Eng. Mater. Struct.
8756-758X,
14
(
5
), pp.
499
513
.
21.
Chiew
,
S. P.
,
Gupta
,
A.
, and
Wu
,
N. W.
, 2001, “
Neural Network-Based Estimation of Stress Concentration Factors Steel Multiplanar Tubular XT-Joints
,”
J. Constr. Steel Res.
0143-974X,
57
(
2
), pp.
97
112
.
22.
Bian
,
L. C.
, and
Lim
,
J. K.
, 2003, “
Fatigue Strength and Stress Concentration Factors of CHS-to-RHS T-Joints
,”
J. Constr. Steel Res.
0143-974X,
59
(
5
), pp.
627
640
.
23.
Chiew
,
S. P.
,
Lie
,
S. T.
,
Lee
,
C. K.
, and
Huang
,
Z. W.
, 2004, “
Fatigue Performance of Cracked Tubular T Joints Under Combined Loads. I: Experimental
,”
J. Struct. Eng.
0733-9445,
130
(
4
), pp.
562
571
.
24.
Ghanameh
,
M. F.
,
Thevenet
,
D.
, and
Zeghloul
,
A.
, 2006, “
Evaluation of Stress Concentration of Planar Joints
,”
Trans. Nonferrous Met. Soc. China
1003-6326,
16
(
1
), pp.
S1
S10
.
25.
1975, “
Indian Standard Specification for Structural Steel (Standard Quality)
,” IS, 226, Bureau of Indian Standards Institution, New Delhi.
26.
Ramachandra Murthy
,
D. S.
, 1993, “
Corrosion Fatigue Behaviour of Steel Tubular Joints of Offshore Structures
,” Ph.D. thesis, Anna University, Chennai, India.
27.
Thandavamoorthy
,
T. S.
, 1998, “
Assessment and Rehabilitation of Damaged Steel Offshore Structures
,” Ph.D. thesis, Anna University, Chennai, India.
28.
Ramachandra Murthy
,
D. S.
, 1996, “
Static and Fatigue Strength of Steel Tubular Joints
,”
Fatigue in Offshore Structures
,
W. D.
Dover
and
A. G.
Madhava Rao
, eds.,
Oxford & IBH Publishing Co.
,
New Delhi, India
, Vol.
1
, pp.
311
333
.
29.
Soh
,
A. K.
, and
Soh
,
C. K.
, 1992, “
SCF Equations for TK Square-to-Round Tubular Joints
,”
Int. J. Offshore Polar Eng.
1053-5381,
2
(
2
), pp.
141
150
.
30.
Lee
,
M. M. K.
, and
Dexter
,
E. M.
, 2004, “
Finite-Element Modelling of Multi-Planar Offshore Tubular Joints
,”
ASME J. Offshore Mech. Arct. Eng.
0892-7219,
126
(
1
), pp.
120
128
.
31.
Lie
,
S. T.
,
Chiew
,
S. P.
,
Lee
,
C. K.
, and
Huang
,
Z. W.
, 2004, “
Fatigue Performance of Cracked Tubular T Joints Under Combined Loads. II: Numerical
,”
J. Struct. Eng.
0733-9445,
120
(
4
), pp.
572
581
.
32.
Lloyd’s Register of Shipping
, 1997, “
Stress Concentration Factors for Simple Tubular Joints Assessment of Existing and Development of New Parametric Formula
,” Health and Safety Executive Offshore Technology Report No. OTH 354.
33.
Yamasaki
,
T.
,
Takizawa
,
S.
, and
Komatsu
,
M.
, 1979, “
Static and Fatigue Tests on Large Size Tubular T-Joints
,”
Proceedings of the 11th Annual Offshore Technical Conference
, Houston, TX, Apr. 30–May 3, Paper No. 3424, pp.
583
591
.
34.
Berge
,
S.
, 1996, “
Fatigue Strength of Tubular Joints
,”
Fatigue in Offshore Structures
,
W. D.
Dover
and
A. G.
Madhava Rao
, eds.,
Oxford & IBH Publishing Co.
,
New Delhi, India
, Vol.
1
, pp.
335
358
.
35.
Hauch
,
S. R.
, and
Bai
,
Y.
, 2000, “
Bending Moment Capacity of Pipes
,”
ASME J. Offshore Mech. Arct. Eng.
0892-7219,
122
(
4
), pp.
243
252
.
36.
Leen
,
S. B.
, and
Hyde
,
T. H.
, 2000, “
On The Prediction Of Elastic-Plastic Generalized Load-Displacement Responses for Tubular Joints
,”
J. Strain Anal.
0022-4758,
35
(
3
), pp.
205
220
.
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