Experimental studies of embedment length of precast bridge pier with socket connection to pile cap

•Socketed pier to pile cap can achieve comparable seismic performance as CIP one.•Reduced embedded length (0.5D) is verified reliable under lateral cyclic loading.•Embedment length greatly affects the numerically calculated stress of socket wall.•Minimum embedment length is proposed based on the allowable grouting stress. Socket connections are recommended to connect precast members in accelerated bridge construction (ABC) due to their advantages over other connecting methods. The primary objectives of this study are to evaluate the seismic behavior of socketed piers with different embedment lengths, and explore the minimum embedment length for designing pier-pile cap socket connections. The numerical analysis suggested that the stress distribution of the socket wall was greatly influenced by the embedment length, and proposed a way to estimate the minimum embedment length based on the allowable stress of grouting. Accordingly, specimens were designed and tested under lateral cyclic loading with a constant vertical load. The experimental results showed the seismic behavior of all specimens were comparable. That is, different embedment lengths could reach the same expected flexural failure mode, i.e., the plastic hinge region formed at the bottom of the pier above the pile cap. And the results also verified that the embedment length for socketed piers into pile caps can be reduced due to a different load mechanism as compared to that of a spread footing. Considering the strength degradation of bonding grout for the real bridge practices, the minimum embedment length should be multiplied a safe factor.