Ultimate Strength Of Damaged Tubular Members

Duan, L. (California Department of Transportation) | Chen, W.F. (Purdue University) | Loh, J.T. (Exxon Production Research Co)

OnePetro 

ABSTRACT:

A moment-thrust-curvature·based procedure for calculating the behavior and ultimate strength of damaged tubular members is presented. The new set of moment-thrust-curvature expressions for damaged or undamaged tubular members developed by the authors is used. A computer program, BCDENT, was developed, whose capability includes analysis of single or multident tubular members subjected to axial compression, end moments, and distributed or concentrated lateral loads. In this paper the validity and accuracy of the moment-thrust-curvature approach for determining the ultimate strength of damaged tubular members are verified by comparing analytical predictions with the available 151 test results.



INTRODUCTION


Owing to their low drag coefficient in comparison to other structural shapes, tubular members are used extensively in offshore structures. These members are generally subjected to gravity, wind, wave and current loads. For members in the wave zone, they often experience localized damage caused mainly by supply workboat collisions or dropped heavy object impacts. In the last two decades, experimental and analytical research on structural tubes has made significant progress in establishing refined criteria for the design of undamaged cylindrical tubular members in offshore platforms (Marshall, 1970; Sherman, 1976; Chen and Ross, 1977; Toma and Chen, 1979; Sherman, 1982; Chen and Han, 1985; Loh, 1990). However, available design specifications (API-RP-2A, 1989; API-RP-2A-LRFD, 1989; AISC-LRFD, 1986; AISC-LRFD, 1989) give no specific information on how localized damage affects the behavior and strength of dented tubular members under field service conditions. To assess the fitness of these offshore structures in service, technical information is needed for these dented members in terms of both their behavior and ultimate strength. Research reported in the open literature has, in the past, focused particular attention on dented members subjected to axial compression combined with negative bending (compression at the dent).