Negative Shear Lag in Framed‐Tube Buildings

Abstract

Occurrence of negative shear lag in framed‐tube buildings under lateral loading is reported in the literature, but explanation of its origin and comprehensive studies of it are lacking. The present paper separates column axial‐force distribution in a story into two modes; one contributing to the positive shear lag and the other to the negative shear lag. The net shear lag, positive or negative, is the resultant of the axial‐force distributions in these modes. Further, an analogy between shear‐lag behavior of a uniform box girder and uniform framed‐tube building is established by interpreting structural parameters occurring in the closed‐form solution of a box girder in terms of those of the framed‐tube building. Adequacy of the proposed analogy is demonstrated. Structural parameters governing the shear‐lag behavior are identified, and their effect and of different loading types is studied.