Application of Orthogonalised Load-Deflection States to the Study of Grout-Filled Damaged Tubular Members

Framed off-shore structures are normally made of tubular members. These members are prone to damage by collision from supply boats or by the impact of dropped objects.

The damage usually takes the form of a dent, overall bending (out of straightness) or a combination of both of these effects.  Experimental and theoretical work has indicated that such damage can cause a significant loss of member strength and that grouting is an effective way of repair for tubular members with a moderate degree of damage.

As part of a Masters thesis,  the residual strength of damaged off-shore structures was studied and the effectiveness of grouting on strengthening an entire platform was investigated [1-3].  This study extended an existing software program based on Orthogonalised Load-Deflection States for establishing the pre- and post-ultimate force-displacement relationships of damaged tubes and grout filled damaged tubes.  Numerical modelling of small scale specimen of damaged grouted tubes was found to be in good agreement with experimental results.  Numerical results of a parametric study of a complete offshore platform showed that the initial strength of the platform, prior to damage of a critical member, can be recovered by the proposed grouting method.  A set of typical load-deflection curves from the parametric study can be seen below.

1. Saleh, A. and Parsanejad, S, : Application of orthogonalised load-deflection states to the collapse of grout filled damaged tubular members. Proceedings of the Fifth International Conference on Civil And Structural Engineering Computing. Edinburgh 17-19 August, 1993.

2. Zhou, T., Saleh, A., and Parsanejad, S : Effect of grouting of damaged tubular members on the behaviour of framed offshore structures. Proceedings of the Australasian Structural Engineering Conference, 21-23 September, 1994, Sydney Australia.

3. Zhou, T., Saleh, A., and Parsanejad, S : On The Section Capacity of Grout Filled Damaged Tubular Members.