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原文传递 Load Rating and Retrofit Testing of Bridge Timber Piles Subjected to Eccentric Loading.

题名：	Load Rating and Retrofit Testing of Bridge Timber Piles Subjected to Eccentric Loading.
作者：	Andrawes, B.; Caiza, P.; Shin, M.
关键词：	Bridges(structures); Deflection; Dynamic Structural Response; Laboratory Tests; Load Bearing Tests; Loads(forces); Maintenance; Mechanical Properties; Roadbeds; Service Life; Structural Timber; Trestl
摘要：	This report first evaluated the load rating procedure currently in use by the Illinois Department of Transportation (IDOT) for rating timber piles supporting multiple-span, simply supported bridges. For simplicity, these piles are often rated under concentric loads, and the effect of bending in the piles is neglected. Recent studies have shown, however, that under highly eccentric live loads, the effect of bending moments in the piles is of great importance and could have an impact on the piles load rating. The report proposed an alternative structural load rating method for timber piles based on the National Design Specification for Wood Construction (NDS), which took into consideration the effect of combined compression-flexure behavior of piles. This method was used to conduct a parametric study to investigate the effect of several geometric and structural parameters on the load rating of bridge timber piles using 3-D finite element models of concrete deck bridges supported on groups of timber piles. The results showed that the proposed load rating method produced significantly lower ratings for piles with moderate to high levels of deterioration, as compared to the ratings obtained using the conventional approach. Among the studied parameters, the length of piles was found to have the most significant impact on the load rating of the piles. The report also presents a study on examining a fiber reinforced polymer (FRP)-based retrofitting method for timber piles subjected to combined axial and bending loading. A total of twenty pile specimens were tested in the study, four under compressiononly load and sixteen under compression-flexure load. Each specimen was tested twice, before and after retrofitting with glass FRP (GFRP) or carbon FRP (CFRP) sheets. To assess the impact of realistic field conditions, different details of the FRP retrofit technique were investigated, including using mortar shell, introducing a mortar-filled wedge in the tested specimen to mimic
报告类型：	科技报告