To further understand the impact factor (IF) of bridges under moving vehicular loads

key problems such as the basic concept of IF

IF for different responses and positions were discussed in detail by combining theoretical derivation and numerical simulation and considering the physical significance of IF. Results show that the IF in the current specification was only a median parameter for convenient design

which had no actual physical meanings. IFs of different responses were not the same

and IF of moment was smaller than that of deflection in most cases. Moreover

IF in various sections were different

where the IF of pier-top section was the largest

followed by that of abutment span

and then that of center span. For two sections located symmetrically

the IF of the latter section in the direction of moving vehicles was bigger. Due to different principles

a more conservative value of IF can be used for design

but it cannot be directly utilized in evaluation. In the end

recommendations of IF for design and evaluation of dynamic performance of bridges subjected to moving vehicular loads were proposed

respectively.