Experimental Evaluation of Dowel Action in Ultra-High Performance Concrete

To analyze and design the reinforced concrete structural members correctly, their behavior must be evaluated under different loadings. The efficiency, accuracy and speed of the methods of structural analysis depend on the use of suitable behavior models. In reinforced concrete structures, the concrete will be cracked under normal loadings since it has a relatively low tensile strength. Therefore, it is important to understand stress transfer mechanisms in the cracked surfaces to evaluate the response of reinforced concrete structures. In the present study, an experimental program is developed to identify the cracked surface behavior under shear loading. The test specimens made of ultra-high performance concrete are used to measure the shear transferred by longitudinal bars (dowel action). Based on the results of the tests and other studies, we present a suitable model for the shear mechanism through the bars in the cracked surfaces of ultra-high performance concrete. The results show that inclined crack decreases the dowel capacity, so that the dowel capacity of samples B6, B7, and B8 decreases to 33%, 50%, and 61% compared to sample B5 (with a 90° angle between notch and bar). The results show the proper accuracy of the equations proposed for estimating the dowel shear-displacement curve in which the correlation was in range 0.972–0.997, between the proposed model and test results.