Study of the Impacts of Implements of Husbandry on Bridges Volume I: Live Load Distribution Factors and Dynamic Load Allowances, TR-613 August 2017

(2017) Study of the Impacts of Implements of Husbandry on Bridges Volume I: Live Load Distribution Factors and Dynamic Load Allowances, TR-613 August 2017. Transportation, Department of

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Abstract

The objectives of this study were to develop guidance for engineers on how implements of husbandry loads are resisted by traditional bridges, with a specific focus on bridges commonly found on the secondary road system; provide recommendations for accurately analyzing bridges for these loading effects; and make suggestions for the rating and posting of these bridges. To achieve the objectives, the distribution of live load and dynamic impact effects for different types of farm vehicles on three general bridge types—steel-concrete, steel-timber, and timber-timber—were investigated through load testing and analytical modeling. The types of vehicles studied included, but were not limited to, grain wagons/grain carts, manure tank wagons, agriculture fertilizer applicators, and tractors. Once the effects of these vehicles had been determined, a parametric study was carried out to develop live load distribution factor (LLDF) equations that account for the effect of husbandry vehicle loads. Similarly, recommendations for dynamic effects were also developed. The live load distribution factors and dynamic load allowances are the primary subjects of this first of three report volumes. Finally, suggestions on the analysis, rating, and posting of bridges for husbandry implements were developed. Those suggestions are covered in the second volume of the report. The third volume of the report contains six appendices that include the 19 mini-reports for field tested and analytically modeled steel-concrete, steel-timber, and timber-timber bridges, the farm implement and bridge inventories for the project, and survey responses.