Evaluation of the load distribution of timber slab bridge and the efficiency of the retrofit methods

Abstract

Timber slab bridges are commonly used in rural regions because of their simple construction and low costs. However, a review of the bridge manual indicates that there is no specific guidance or very similar guidance to the current nationwide bridge codes with respect to the calculation of wheel load distribution and strengthening/enhancing methods. The objective of this research is to evaluate the load distribution for timber slab bridges and the efficiency of the retrofit methods. To achieve this objective, ten timber slab bridges were identified for a program of bridge live load tests. Three of them were tested twice, once before and once after bridge strengthening measures were employed. The data collected from the field test program was utilized to calculate the equivalent strip width (ESW), and the results were compared with the codified values. In addition, a series of finite element (FE) models were created based on these ten field-tested bridges and validated against the field-collected data. The validated FE models were utilized for a parametric study to evaluate the wheel load distribution and the performance of various retrofit methods on the bridges with different truck loading, bridge geometry, and retrofit approaches. Based on the results from the field tests and analytical simulation, an equation to predict the equivalent strip width for the timber slab bridges was developed with consideration of numerous variables.