Research On Shear Capacity And Reliability Of Recycled Concrete Beam

This research is developed from “analysis on mechanical properties andmicrostructure of recycled concrete” that is funded by Natural Science Foundation ofHeilongjiang province.On the basis of the recycled concrete mechanical properties and the shearexperiments of recycled concrete beams all over the world, we investigated the factorsthat influence the shear capacity and the calculation method of shear capacity. Besides,the reliability analysis for the advised formulas of shear capacity was conducted. Themain work and conclusion of the research were shown as follows:(1) Through the investigation of sixty three recycled concrete beams of shearexperiments all over the world, we found that the recycled concrete beams have littledifference in failure modes with virgin concrete beams. In addition, the effect of stirrupratio, shear span to depth ratio and concrete strength to the ultimate shear load of RRCbeams are the same to that of RCC beams.(2) Computer numerical simulations by ANSYS were performed. In order toconfirm the model is correct, firstly, we should build a recycled concrete beam modelaccording to the exist experiment, then, the comparison between the test results and thecalculated results should be done. Lastly, we designed a new shear experiment in orderto study how the longitudinal reinforcement ratio and the sectional dimension influencethe beam shear capacity and deflection.(3) The conversion between the strength indexes of recycled concrete weredetermined. Furtherly, the shear bearing capacity calculated by the code formulas ofChina, USA, Europe were compared to the test values and it showed that the three codeformulas were all applicable to the recycled concrete beams.(4) Based on the plastic theory, we put forward a new shear formula considering theeffect of cracking on the shear capacity. The calculated value using new formula can fitthe test value well.(5) The reliability analysis of shear formula of RC beams was given. The influenceof different factors (such as concrete and steel strength, shear span to depth ratio, load effect ratio, live load types and stirrup ratio) on the reliability index was studied. Theresults showed that live load types and load effect ratio have a siginificant influence onthe reliability index, and then were stirrup ratio, shear span to depth ratio and steel type,however, concrete strength has little influence on the reliability index.