The seismic damage mechanism of Huilan interchange

which was severely damaged during Wenchuan earthquake

was studied through numerical simulation and post-earthquake investigation.The simulation results show that the bearing at the top of the most shortest No.1 pier was firstly damaged due to sliding.Then

seismic action concentrated on the next shortest No.2 rigid frame pier which has a larger stiffness.No.2 pier firstly yielded in flexure

and as the lateral displacement increased

the No.2 pier was dominated by shear capacity

and eventually failed in flexure-shear modes.By field investigation

it was found that the short rigid frame piers with largest lateral stiffness suffered severely damage while other piers suffered slight-to-moderate damage

which including concrete cover spalling

concrete cracking and sliding damage of the rubber bearing on the top of piers.It is concluded that the simulation results agree well with post-earthquake investigations.