Seismic behaviour of hybrid-fibre reinforced concrete shear keys in immersed tunnels

Abstract This study aims to develop hybrid fibre reinforced concrete (HFRC) for shear keys used in conjunction with immersed tunnels in the Hong Kong–Zhuhai–Macau megaproject. First, HFRC was developed for shear keys, and its mixture proportions were optimised. Second, a testing programme was carried out with 15 specimens, to investigate the seismic behaviours of shear keys with the developed HFRC. The test results reported the failure mode, displacement with respect to the load, energy dissipation capacity, and the ductility of the shear keys with HFRC in the presence of horizontal hysteretic loads. The influences of different material parameters on the seismic behaviours of shear keys were analysed and discussed. Analytical models were also developed to predict the ultimate load-carrying capacity of the shear keys by regression based on the test results. Validations of the predictions from the developed analytical models confirmed their accuracy when compared with test results.