Assessing Dynamic Load Allowance of the Negative Bending Moment in Continuous Girder Bridges by Weighted Average Method

Abstract

Accurate acquisition of dynamic load allowance (DLA) based on measurement data is essential to the safety assessment of a bridge. When static load tests cannot be achieved, and filtering fails, the estimated DLAs from the experimental method vary widely due to the choice of a left or right band. In this paper, the proposed weighted average method (WAM) is used to possibly solve the above problem in continuous gird bridges. Two-span and three-span precast concrete box-gird bridges were selected to optimize intercepted segments of WAM for the first time with the assistance of standard deviation and coefficient of variation in statistics. Then, a DLA measurement case of the negative bending moment was utilized to verify the validity of the WAM. The results show that the intercepted segments of 10/16 to 1 times the span length were suitable for the WAM to calculate the DLA of the negative bending moment due to small offset moments and stable variation coefficients. The WAM had a strong anti-interference ability of outliers filtering in “bad data,” which differed significantly from the experimental method. In three measurements of a field bridge, DLAs obtained by the WAM had less dispersion than the experimental and low-pass filtering methods.