| Bridge dynamic loads are very important for pavement and bridge design. However, traditional methods can only measure static axle loads and are therefore, subject to bias. The main objective of this study is to develop a moving force identification system (MFIS) to identify moving time-varying axle loads on bridges. The secondary objective account for the dynamic axle loads with the aid of the MFIS developed.; The moving force identification system (MFIS) developed, consists of four methods which are the interpretive method I (IMI), interpretive method II (IMII), time domain method (TDM) and frequency-time domain method (FTDM). A preliminary comparison of the four methods involved in the MFIS has been carried out based on bridge-vehicle model in the laboratory. The singular value decomposition (SVD) technique has been introduced to solve the over-determined equation sets for improvement of accuracy of the MFIS. In addition to the force identification from bending moment responses of bridges, acceleration responses are also used to investigate the feasibility of moving force identification. The MFIS has been further applied to the identification of multiple axle loads on bridges. Different vehicles with three suspension systems and two connection ways between tractor and trailer have been simulated theoretically as well as in the laboratory. The effects of the characteristic parameters of both vehicle and bridge have been assessed based on the identified results.; Much effort has concentrated on investigating the correlation of higher impact factors with different parameters of two bridge-vehicle systems. One is various multiple axle vehicles and beam-like bridge system, and the other the short span multi-girder plate bridge and vehicle system.; It is concluded that the MFIS developed is a successful moving force identification system. After introducing the SVD technique, the system has been significantly improved, particularly for the FTDM method involved in the system. The SVD makes the system more stable and effective. In addition, the MFIS can be effectively used to account for bridge dynamic loads. The impact factors of the bridge can be evaluated and the bridge-friendly vehicles can then be identified. |
