Load redistribution pattern in a RC moment frame due to excavation-induced ۳D ground surface settlement profiles

Abstract

Following abnormal events, identification of load redistribution pattern in the load-bearing elements is an important issue in the field of structural engineering. As a possible event, one can imply to initiation of excavation-induced large differential settlements under the columns of common reinforced concrete (RC) moment frames. A large portion of existing literature have studied the effect of single-column settlement scenarios or tunnel-induced ground movements on 2D frames, however. Using two series of real ground surface settlement profiles (called medium and large) representing deep excavation adjacent to the construction site, 8 analysis cases were defined to gradually impose differential settlements under the columns in this paper. Apart from different 3D settlement profiles, the structure was assumed to be located on the corner or center of excavation edge, and two directions were also considered for the building plan. Based on the findings of the numerical models, the axial compressive force significantly decreased in a series of highly settled columns. Also the columns which were relatively far from the location of maximum settlement made key contribution to redistribution of loads. Moreover, a large number of columns experienced tensile axial forces in some of the cases with larger surface settlement imposed. The change in the direction of beam flexural moments in conjunction with some columns (not limited to the column having the largest settlement) shed light on possibility of damage in an extensive area of the building plan.