The shear wall configuration makes generally access difficult to the public lobby area at the base in tall buildings. Larger openings at ground floor level can be achieved by the use of large transfer girders to collect the vertical loads from the shear walls and then distribute them to widely spaced columns that support the shear walls. Unlike normal deep beams, there is no particular span-depth ratio for estimating the structural behaviour and failure mechanism of transfer beams. When a transfer beam supports an in-plane loaded shear wall, strong interaction takes places....[ Read more ]

The shear wall configuration makes generally access difficult to the public lobby area at the base in tall buildings. Larger openings at ground floor level can be achieved by the use of large transfer girders to collect the vertical loads from the shear walls and then distribute them to widely spaced columns that support the shear walls. Unlike normal deep beams, there is no particular span-depth ratio for estimating the structural behaviour and failure mechanism of transfer beams. When a transfer beam supports an in-plane loaded shear wall, strong interaction takes places.

The thesis systematically investigates the failure mechanisms of the transfer beams supporting shear walls in tall building. The non-linear finite element analysis has been conducted to investigate the failure modes, the failure loads and load transfer mechanism. It is shown that the mode of failure for the transfer beam changes from a shear failure to a flexural-shear failure then turning into a flexural failure according to different span-depth ratio or the width of the beam. The cracking loads and the failure loads under different span-depth ratio and width of the transfer beams have been investigated. Based on the failure mechanisms analysis, the recommendations for preliminary sizing of the transfer beam are presented. The results have been helpful for engineers to choose an efficient and reasonable size for the transfer beams in the preliminary design.

The detailed linear finite element analysis has been conducted using the finite element code SAP2000. The interaction between the transfer girder and the shear wall has been investigated. The stress distributions in the shear walls, the distribution of the flexural moments and the tension forces in the transfer beams are presented. The relevant parameters that significantly affect the structure behaviour, such as the span-depth ratio, stiffness of the support columns and the width of the transfer beam, have been highlighted. Based on the calculation and reasonable simplification, a transfer beam-shear wall system can be reduced to an equivalent interaction-based portal frame. A set of interaction-based design tables is constructed for the transfer beam and support columns, from which, the useful internal forces in the wall-beam system can be quickly calculated.

Furthermore, based on the box-foundation analogy, design formulas for determining the bending moment and axial force of the transfer beams are developed. Some new parameters are introduced, which present the interaction behaviour between the wall and the beam. With the proposed formulas, the flexural moment and the axial force at mid-span of the transfer beam can simply and quickly be calculated. In addition, from the formulas, the interactive behaviour can also be clearly presented by the new parameters. The proposed formulas provide a simple, efficient and accurate simplified method for practical design of transfer beams supporting in-plane loaded shear walls.