Characterization and Prediction of Microcracking in Reinforced UHPFRC Beams under Bending

摘要

The capacity of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) to develop multiple micro-cracks instead and delay the localization of major cracks has great impact on the permeability and durability at serviceability state. In order to assess the durability of reinforced UHPFRC structures or rehabilitation layers, methods that accurately predict the microcrack width are necessary. This work aims at assessing the accuracy of some current analytical models to predict the crack width and growth of reinforced UHPFRC beam in bending by means of Digital Image Correlation (DIC) analysis of 4-point bending tests. DIC analysis was successfully employed to estimate the microcrack width and their spacing during loading. In particular, the following methods for predicting the growth of cracks of a reinforced FRC member are considered: (ⅰ) Eurocode 2; (ⅱ) RILEM TC 162-TDF; (ⅲ) the one proposed by Moffatt; (ⅳ) the one proposed by Deluce. As expected Eurocode crack model overestimates the crack width as it does not consider the fiber contribution. RILEM and Moffatt models well predict the maximum crack width, but Deluce method is the most accurate to predict the mean crack width. The estimation of the crack spacing seems to the be critical factor which may require further improvement, especially for the crack spacing at serviceability states.