Prediction of Offshore Foundation Performance under Combined Horizontal-Moment loading in the Niger Delta of Nigeria

The performance of offshore foundation with varying area, A, on clay in the Niger Delta subjected to combined horizontal – moment load has been studied. Undrained shear strength,su, of soil were evaluated from triaxial test results of offshore soil samples. Horizontal forces were evaluated from the impact of varying wave heights on circular piles from which moment loads, M, were subsequently evaluated. Under pure moment loading, the maximum moment ,Mu, ranged from M of 0.997Mu to 1.00Mu ,but under combined loading, the maximum moment, M of 1.085Mu coincided with a horizontal load ,H, of 0.56Asu for ratio of foundation depth to breadth less than one (Df /B<1). For cases of Df/B>1.0, it is noticed that at zero horizontal load, the ratio of moment to maximum moment is equal to one ((M/Mu=1) irrespective of the foundation size. Under combined loading, the maximum moment capacity occurred at M of 1.0886 Mu and it coincided with a horizontal load, H, of 0.492Asu.