In order to estimate the strain extreme value of bridges accurately, selecting a reasonable threshold of GPD model is significant to fit the strain peaks caused by vehicle loads. In this paper, according to the estimated extreme values based on a GPD model with different thresholds, the characteristics and application scope of four commonly used threshold estimation methods were discussed. Results show that the estimated extreme values of GPD model are larger than the theoretical values in general. Threshold selection of GPD model should balance the deviation and variance of estimated extreme values. With the increasing of the threshold, the deviation starts to decrease rapidly first, and then slowly, while the variance starts to decrease first, then increases. Based on this, a new threshold selection method of GPD model to estimate the extreme values of bridge strain caused by vehicle loads is given, finally a real bridge is chosen to verify the method and satisfied results are obtained.
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