Issue 35

W. Xu et alii, Frattura ed Integrità Strutturale, 35 (2016) 481-491; DOI: 10.3221/IGF-ESIS.35.54 490 Figure 15: Curves of load-displacement (corrosion rate 15% ). The above figures demonstrate that, bearing capacity and ultimate displacement both decrease with the increase of axial compression ratio; when corrosion is mild, rigidity of component increases with increase of axial compression ratio; component with large axial compression ratio yields early and bearing capacity and ultimate displacement declines greatly. When corrosion rate is low or steel reinforcement is not corroded, curves of load-displacement when axial compression ratio is 0.6 differ greatly with curves when axial compression ratio is 0.2 and 0.4. That is because that, excessively higher axial compression ratio severely affects ducility of the structure. Moreover, when protective layer cracks and corrosion rate is high, bearing capacity and ultimate displacement decline steadily with the increase of axial compression ratio. Under the same corrosion rate, joint model which is not corroded or slightly corroded is less affected by axial compression ratio; the influence is the most notable when corrosion rate is 5%. When axial compression ratio is 0.4, joints have stronger bearing capacity and ultimate displacement. But when axial compression ratio is 0.2, bearing capacity fails to be stronger. When it is 0.6, bearing capacity and ultimate displacement decrease sharply. C ONCLUSION o sum up, corrosion rate of steel reinforcement and axial compression ratio have large influence on corroded reinforced concrete framework joints; joints show obvious degeneration with the increase of corrosion rate. Changes of mechanical performance can be summarized as declined bearing capacity, degraded rigidity, changed ducility and decreased ultimate displacement. Under coupling effect of inside corrosion and external load, bearing capacity of component remains unchanged, but ultimate displacement decreases obviously, when corrosion rate is excessively large (15%). Corrosion rate is a key factor influencing mechanical performance of component, which can impact endurance quality of old framework. R EFERENCES [1] Cairns, J., Du, Y., Law, D., Influence of corrosion on the friction characteristics of the steel/concrete interface, Construction and Building Materials, 21(1) (2007) 190-197. [2] Zou, D.J., Liu, T.J., Qiao, G.F., Experimental investigation on the dynamic properties of RC structures affected by the reinforcement corrosion, Advances in Structural Engineering, 17(6) (2014) 851-860. [3] Ye, L.P., Fang, E.H., Research overview of stress performance of steel reinforced concrete elements, China Civil Engineering Journal, 33(5) (2000) 1-12. [4] Xue, J.Y., Zhao, H.T., Yang, Y., Seismic behavior and construction method of steel reinforced concrete joint, World Information on Earthquake Engineering, 18(2) (2002) 61-64. [5] Xu, M., Su, L.L., Cheng, W.R., Chen, Z.F., Test on combined steel and concrete column and reinforced concrete composite frame joint, Building Structure, 33(7) (2003) 36-39. [6] Yang, Z.Y., Hu, J.N., Zhang, Z., Reinforcement of damaged frame joint with carbon fiber by finite element analysis, Procedia Earth and Planetary Science, 5 (2012) 198-202. T