Seismic response of a multi-span bridge is investigated in this study using an Internet based testing platform. The platform, NetSLab, was developed based on client/server concept along with a proposed data model and communication protocols. The platform is capable of transferring control and feedback data and signals among remotely located structural testing laboratories or computers connected by Internet. In these tests, a three-pier bridge system was simulated in which a Glass Fiber Reinforced Plastic (GFRP) retrofitted reinforced concrete pier was tested physically in Hunan University and a Carbon Fiber Reinforced Plastic (CFRP) reinforced concrete retrofitted pier was tested physically in Harbin Institute of Technology and the third one was simulated numerically in Tsinghua University. The bridge was loaded to simulate the responses under ground motions corresponding to earthquake hazards for a highly seismic location with 63%, 10%, 2% chance of exceedance in 50 years. The experiments demonstrate that the bridge structure with retrofitted piers has adequate behavior under earthquake loading even in areas of high earthquake intensity.