High-Rise Structures with Belt Bracing Subject to Lateral Load

Abstract

This paper presents simple methods of analysis for preliminary design of high-rise structures comprising reinforced concrete shear walls or steel trussed frames with a perimeter belt bracing structure consisting of steel trusses, subjected to horizontal loading. The methods are based on the analysis of facade rigger braced structures where horizontal steel trusses (web riggers), located in the two end facades (web frames), are positioned in a direction parallel to the lateral loading on the building. Perpendicular to the horizontal load additional horizontal steel trusses in the wind and lee sides of the building, “flange trusses”, complete the belt bracing structure. The method is focused on the contribution of the flange trusses to the lateral stiffness of the structure. The shear-lag due to differential strain in the flange frame columns along the wind and leeward facades is caused by bending and racking shear deformations in the flange trusses and is taken into account. In an approximate method the flange columns are replaced by a continuous medium of equivalent axial stiffness, i.e. a beam on an elastic foundation. The proposed methods of analysis, for use in the initial stages of the structural design of proposed tall buildings, offer simple and rapid means of establishing the influence of belt structures on horizontal deformations of the high-rise structure and internal forces.