Some structures such as tall buildings, offshore platforms, and bridge bents are subjected to lateral loads of considerable magnitude due to wind and wave actions, ship impacts, or high-speed vehicles. Significant torsional forces can be transferred to the foundation piles by virtue of eccentric lateral loading. The testing program of this study includes one group consists of 3 piles, four percentages of allowable vertical load were used (0%, 25%, 50%, and 100%) with two L/D ratios 20 and 30, vertical allowable load 110 N for L/D = 20 and 156 N for L/D = 30. The results obtained indicate that the torsional capacity for pile group increases with increasing the percentage of allowable vertical load, when the percentage of allowable vertical load was 100% and L/D ratio (20) the torsional capacity for pile group increases about 42% if compared with the torsional capacity when the percentage of allowable vertical load was 0% for the same L/D ratio. Also increasing L/D ratio leads to increasing the torsional capacity of pile group, when the percentage of allowable vertical load is 100% and L/D ratio (30), the torsional capacity for pile group increased about 51% if compared with torsional capacity when L/D ratio was (20) for the same groups and the same percentage of allowable vertical load. At failure the twist angle for pile group remain constant 3° when the percentage of allowable load change from 0% to 100 and L/D ratio 20, while it decreases from 2.9° to 2.7° when the percentage of allowable load change from 0% to 100% respectively and L/D ratio 30.
