Analysis On Equivalent Cross Section Parameters For RC Composite Column Subjected To Secondary Load

At present, the reinforcement and reconstruction is being developed rapidly in China.Strengthening with reinforced concrete cover is an economical and efficient method that isbeing widely used. In the design of composite columns, the present code suggest thedesigners to simply superimpose the capacity of newly casted concrete to the oldcounterparts; and then a reduction factor is introduced to compromise the overall bearingcapacity. In the seismic calculations, the traditional way is to consider the capacity ofnewly casted concrete as the old counterparts. However, this method may lead to error instiffness estimation of reinforced components. Since the current structural design softwarecannot input appropriate composite column parameters, the thesis is aim at deducing theformula of equivalent cross-section parameters, which is of theoretical and engineeringimportance.The article focused on the section-enlargement Method which is widely used inpractical engineering. Many important situations and factors are taken into consideration.They are the fact that the sustained load cannot be completely released, the strength ratioand area ratio of new concrete and old concrete. Deducing the theoretical solution ofnormal section bearing capacity, we obtain the simplified formula of composite column.To verify the validity of the formula, a numerical model is established using ANSYSbased on the data from literature. Finally, the deduced formula is applied to a establishedmodel analysis. And by further analysis the internal force and reinforcement configuration,the case study verifies the applicability of the deduced formula.Based on the related theories and results of the experimental results, the finiteelement analysis and the case study, the Section-Enlargement Method is verified. Theresults show that: the equivalent cross-section method can factually reflect the behavior ofthe composite column. This method provide a practical basis for numerical simulation ofcomposite column in existing structural design software.