Unified Model Of The I-shaped Reinforced Concrete Members Under The Combined Loads

The I-shaped reinforced concrete member is often under the loads combination of tension,compression,bending,shear and torsion in the actual projects.There is not a complete theoretical system for solving complex problems of the I-shaped reinforced concrete members under the combined loads in the world.Many design codes are the empirical formulas based on the experimental data,and its accuracy needs to be improved.The unified failure calculation model of the I-shaped reinforced concrete members under the combined loads is suggested in this dissertation.The improved ultimate equilibrium theory is used to solve the problem,which is built on the basis of traditional ultimate equilibrium theory.There are two kinds of traditional theories used to solve complex problems of the I-shaped reinforced concrete members under the combined loads,one is the space-truss theory,and another is the ultimate equilibrium theory.But whether the space-truss theory or the ultimate equilibrium theory,the calculation model has imperfections to solve complex problems of the I-shaped reinforced concrete members under the combined loads.Some models ignore the shear resistant effect of the concrete,and some models' formulas are too complex to use,which even need the help of a large computer program,and it is inapplicable in engineering.Compared with space truss theory and limit equilibrium theory,the suggested calculation model takes the advantage of the shear resistant effect of the concrete,through the variation of the twist failure surface angles,the twist failure surface could be determined.After that,the improved ultimate equilibrium theory can deduce the ultimate failure mode,failure mechanism and ultimate bearing capacity of the I-shaped reinforced concrete members under the combined loads.Its concepts are clear.The unified failure formulas are concise,and it can be adopted in engineering.Meanwhile,in order to verify the correctness of the unified failure formulas for the I-shaped reinforced concrete members under the loads combination of tension,compression,bending,shear and torsion,two representative tests are choose.Through the comparison of unified model and test results,the difference and defect can be found,and the unified failure calculation model can be improved.In addition to the use of test data,the numerical analysis is used to adjust the parameters and improve the unified model.The unified model of the I-shaped reinforced concrete members under the combined loads which is suggested by the author is in line with the test data and the numerical analysis results.The research results can provide a reference for engineering and code modifications.