Research On The Seismic Behavior And Design Methods Of Recycled Aggregate Concrete Under Torsion

The use of recycled aggregate concrete（RAC）is a very important issue in environmental sustainability.But they are still sufficient for practical application in civil engineering.A limited number of studies have investigated basic members and frame structure of RAC,whereas investigation on RAC beams under torsional loads do not seem to be sufficient.The main objective of this study has been to know more about the performance of RAC beams under torsion.The first group of numerical experiments were designed according to Box-Behnken theory to obtain the effect of recycled coarse aggregate replacement percentage,compressive strength and some other factors on RAC beams under torsion.Further research,based on the first group of numerical experiments was carried out to know more about the effect of yield stress of reinforcement,cross section dimension and stirrup space on torsion strength of RAC beams and this study had the second group of numerical experiments.The response surface was got by numerical experiment results which were from numerical simulation of ABAQUS and custom code based on the Rotating Angle-Softened Truss Model（RA-STM）.Modification coefficients related to the replacement ratio of recycled aggregate and cross section dimension were got by comparing the difference between the numerical experiment results and the ultimate torque calculated according to concrete structure design codes（ACI318-14,GB50010-2010,EN.1992.1.1:2004 etc.）.The results of this studied showed that lager cross section reduced the difference between calculating by code and experimental results.The correction coefficients were proved to be accurate by the full-scale test results which were form response prediction.