Experimental evaluation of bearing stiffness of concrete under longitudinal bar in ultra high performance concrete

Document Type : Research Paper

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Abstract

In the recent years, extensive experimental and analytical studies on the effect of longitudinal bars in shear transferring (dowel action) has done. Almost all the models presented the theory of Beam on Elastic Foundation (BEF) as the best way to simulate the behavior of dowel action. In this model, the subgrade stiffness of concrete is the most important parameter. This paper presents results of an experimental study on the bearing stiffness of concrete under dowel bars. The tests have been done on Ultra High Performance Concrete (UHPC) . The effect of concrete compressive strength, bar diameter and location of the bar on bearing stiffness of concrete by means of 39 samples were studied. According to the test results, three empirical equations by taking into account various parameters are proposed. Afterward, the ability of these equations as well as relations proposed by previous researchers to predict the amount of bearing stiffness of ultra high performance concrete is evaluated. The results show that the relationships proposed by previous researchers do not sufficient accuracy to calculate the bearing stiffness of UHPC. This can be due to differences in the UHPC ingredient and normal concrete ingredient.

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