Finite Element Analysis of Raft Foundation under Coupled Moment

Abstract

Due to wind wave actions, ships impacts, high-speed vehicles and others resources of loading, structures such as high buildings rise bridge and electric transmission towers undergo significant coupled moment loads. In this study, the effect of increasing the value of coupled moment and increasing the rigidity of raft footing on the horizontal deflection by using 3-D finite element using ABAQUS program. The results showed that the increasing the coupled moment value leads to an increase in lateral deflection and increase in the rotational angle (α◦). The rotational angle increases from (0.014, 0.15 to 0.19) at coupled moment (120 kN.m), (0.29, 0.31 and 0.49) at coupled moment (240 kN.m) and (0.57, 0.63 and 1.03) at coupled moment (480 kN.m) with decreasing the raft thickness from (1.5, 1.0 to 0.5m), respectively. The computed maximum lateral deflection decreases with increasing the rigidity of raft. The maximum deflection decreases from (40 to 3mm) at coupled moment 120 kN.m, (150 to 60mm) at coupled moment 240 kN.m and (210 to 118mm) at coupled moment 480 kN.m with increase raft thickness from (t = 0.5 to 1.5m) and the maximum reduction in maximum stress value and lateral deflection mobilized due to applied coupled moment is noticed when width to thickness of footing ratio is less than (w/t<12). The failure of the footing is noticed when the rotational angle is more than 4◦ (α > 4◦)