Effects of belt trusses on drift control of frame-core tube structures

Abstract

One of the main problems in high-rise buildings is the excessive drifts experienced during earthquake shakings. When dealing with frame-core tube structures, one strategy that could be adopted to reduce lateral deformations when only a limited stiffening is required is to introduce belt trusses. This strategy also has smaller adverse effects on the building space and construction in comparison to the coupled use of outriggers. However, no systematic studies have been conducted on the frame-core tube structures stiffened with only belt trusses. In the present study, an equivalent frame-wall structural model and the corresponding simplified response calculation method were proposed to conduct parametric studies on frame-core tube structures with belt trusses under lateral loadings. The results of parametric analyses indicate that the degrees of the variations of the cross-sectional dimensions of columns and shear walls basically do not change the shape of the IDR profile and the level where the maximum IDR is located. The effectiveness of the belt trusses in reducing the IDRs decreases as the ratio of the story stiffness of the shear walls to the columns, kw/kc, and the ratio of the story stiffness of the beams to the columns, kb/kc, increase or the ratio of the story stiffness provided by the second moment of the column cross-sectional areas about their common centroid to that of the columns, ka/kc, decreases. The optimal stiffening levels for minimizing the maximum IDR move upward as kw/kc increases or ka/kc decreases, whereas kb/kc has negligible influence on the optimal stiffening levels. Simplified equations were also developed to determine the optimal stiffening levels and the corresponding effects in reducing the maximum IDRs.