Dynamic testing and modelling of existing buildings in Hong Kong

Abstract

The dynamic response of building structures under wind and earthquake-induced loading is primarily dependent on the natural vibration periods and the damping ratios. Accurate determination of those dynamic parameters is of utmost importance for design of buildings subjected to dynamic lateral loads. In-situ ambient vibration tests and computer modeling are conducted for six existing reinforced concrete buildings in Hong Kong. Period prediction formulae for real buildings and bare frame models are suggested. Very high discrepancy leading to possible overestimation of the lateral vibration period by 100% using the bare frame models is encountered. The results indicate that bare frame models without consideration of stiffening effects from non-structural components at low-amplitude vibration and the actual stiffness of reinforced concrete at working conditions are unlikely to produce reliable results for dynamic analysis of buildings in particular under service conditions. The implications on wind and earthquake-induced loading due to the inaccurate prediction of the lateral periods by the bare frame model are discussed in detail.