Seismic Assessment of Buildings in Hong Kong with Special Emphasis on Displacement-Based Approaches

This dissertation, "Seismic Assessment of Buildings in Hong Kong With Special Emphasis on Displacement-based Approaches" by MD Neaz, Sheikh, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Seismic Assessment of Buildings in Hong Kong with Special Emphasis on Displacement-Based Approaches Submitted by MD. NEAZ SHEIKH for the degree of Doctor of Philosophy at The University of Hong Kong in June 2005 Given its location far away from any tectonic plate margin, Hong Kong is considered to be a region of low to moderate seismicity. Traditionally, seismic risk to infrastructure in Hong Kong has been considered low, but as a result of the rapid construction of high-rise buildings, complex infrastructure, and industrial facilities during the second half of the twentieth century, seismic risk has increased significantly. The aim of this thesis is to develop a straightforward and comprehensive displacement-based procedure for the seismic assessment of buildings, using existing calculations as a reference, to decide if further seismic investigation is required. Several key studies on the seismic hazard assessment for Hong Kong region have been critically reviewed. Design response spectral parameters at rock sites have been predicted by combining the outcome of the key seismic hazard studies in a logic tree approach. Due to the constraints of the natural topography and the high demand for housing and commercial buildings, reclamation of land from the sea has been widely practiced in Hong Kong. Conditions for reclamation sites along the waterfront provide a classical setting for developing soil resonance, which is notorious for its displacement amplification characteristics. A simplified and rational manual procedure has been developed, based on the results of numerous non-linear time history analyses of 18 representative soil columns in Hong Kong, which can be used to construct realistic soil displacement response spectra that account completely for the effect of soil resonance. Ambient vibration tests have been carried out on some common types of building in Hong Kong. The test results indicate that buildings in Hong Kong are stiffer, and hence fundamental periods are lower, than elsewhere in the world. Significant stiffness contributions from non-structural components (NSC) to the total lateral stiffness of buildings have been observed. The extent of the contribution depends on the structural form and the type of the component. Given the shortcomings inherent in the standard force-based (FB) procedure widely employed for seismic design and assessment, an alternative procedure based directly on displacement (drift) has been developed. Significantly, in the developed drift model the effects of building height (period), deflection shape, and higher mode contributions are accounted for by a series of scaling factors, termed multipliers. These multipliers have been developed from extensive parametric studies and field measurements. The model enables the maximum total inter-storey drift in multi- storey buildings to be accurately determined. Buildings in Hong Kong are not designed for earthquake resistance, and hence NSC are unrestrained. The concept of elastic displacement floor response spectra to model the behaviour of unrestrained NSC has been introduced. Major trends associated with the behaviour of both acceleration and displacement floor response spectra are identified. In order to prevent a possible earthquake disaster, a suitable disaster response plan may