Evaluation of high-strength concrete interior beam-column joints under simulated seismic loading
Leong, Chee Lai
Date of Issue2012
School of Civil and Environmental Engineering
With the rapid proliferation of high-rise buildings, the use of high strength concrete in construction is becoming increasingly common. High strength concrete provides many benefits such as a smaller column area as a result of higher compressive strength thereby creating more useable space within the buildings which can lead to higher commercial value. However, the strength, ductility, and energy dissipation capacity of these beam-column joints may not be adequate to sustain earthquake-induced loads due to the inherent brittle characteristics of high strength concrete. In this research program, the behaviour of high strength concrete interior beam-column joints under reversed cyclic loading was investigated through a rigorous test programme, finite element analysis and parametric studies. The research program summarised in this thesis is aimed at investigating the performance of normal strength concrete and high strength concrete beam-column joints subjected to earthquake actions, which are hitherto not addressed in Singapore. A total of eight high strength concrete beam-column joints were built and tested under reversed cyclic loadings to study the structural behaviour of high strength concrete beam-column joints. All specimens only partially met the seismic detailing requirements in NZS 3101: 2006 and the respective test findings explored the possibility of improving upon the design code NZS3101 to accommodate the use of high strength concrete. Four specimens were tested with zero column axial compressive loading while another four specimens were tested with a column axial compressive loading of 0.3Acfc’. Based on the test results, some relaxation of the bond requirements in beam-column joints is possible as improvement of bond strength was noticed where the bond strength increases with the increase in concrete compressive strength. The congestion of reinforcement in a high strength concrete beam-column joint can be improved when the usage of larger bars are allowed.