Abstract
The effect of opening width is not properly taken into account with the conventional 2D frame analysis, in which hinges are installed at the top and bottom of a virtual beam with decreased stiffness at the opening part. This research proposes a 2D frame analysis method, which can take into account the effect of opening width by installing the rotation spring with torsional stiffness according to the opening width and shape of remaining haunch. This paper investigates the influence of opening at side wall on the members of existing cut-and-cover tunnels by means of 3D FEM. The proposed 2D frame analysis method is also verified by comparing the results with those of 3D FEM and enables to judge the necessity of reinforcement.
