Assessment of low-rise building with transfer beam under seismic forces

An overview of the structural performance of a transfer structure in Hong Kong under potential seismic actions is presented. A hypothetical but realistic low-rise building model has been developed comprising a seven-storey reinforced concrete frame structure with reinforced concrete transfer beams at first floor level. Structural design has been based on the British Standard BS8110 and local practices. Parametric analyses of the moment–curvature relationship of each component have been conducted. By adopting the displacement-based (DB) approach, various seismic assessment methodologies, including response spectrum analysis (RSA), manual calculation, pushover analysis (POA) and equivalent static analysis (ESA) have been implemented. The deformations induced by the predicted seismic actions in Hong Kong are compared with those arising from POA in terms of average lateral drift ratios and maximum interstorey drift ratios arising in the building. Factors influencing the performance of this form of transfer structure are highlighted and discussed. This paper also provides a general indication of seismic vulnerability of common low-rise transfer structures in regions of low to moderate seismicity.