Abstract: A comparison of dynamic amplification factors calculated from bridge strain and deflection of a simply-supported beam and a continuous beam is conducted. Firstly, the strain and deflection dynamic amplification factors are theoretically derived and compared based on a simply-supported beam and a continuous beam under the action of a constant moving force. To consider the effect of dynamic vehicle loading, numerical simulations are performed using a developed vehicle-bridge coupled model while adopting a moving spring mass vehicle model. The results from both the theoretical analysis and numerical simulation show that the strain dynamic amplification factor is less than the deflection dynamic amplification factor and that their ratio is influenced by a number of factors, among which the number of vibration modes used in calculating the bridge responses has a significant influence.