Effect of Tie Beam Rigidity on Strip Footings

This paper presents the effect of the tie beams that connect footings on the contact stress under footings applying the 2-D finite element (FE) technique. It showed that the tie beam rigidity has a significant effect on the average contact stress (P_sm) and corresponding differential settlement under footings. For the inner footing, P_sm decreased with the increase of the tie beam rigidity, whereas P_sm under outer footing increased with the increase of the tie beam rigidity. These effects tend to decrease the differential settlement under the footings. Tie beams redistribute the force acting on the footings. Therefore, it affects P_sm under footings that affects the settlement and the differential settlement. Due to the increase of outer P_sm, the outer footing is required to be increased to reach the standards safety factor for the bearing capacity of soil. In addition, tie beams redistribute the acting loads on footings that are carried from the columns. Therefore, it affects the straining actions of the superstructure members. This paper also clarified that the outer footing settled more than that was estimated regardless of the soil structure interaction. It is important to note that the tie beam rigidity also leads to increase the tilting of outer footings, which is necessary to be accurately calculated and checked with standard requirements.