دانلود رایگان مقاله انگلیسی بررسی تجربی بر روی رفتار لرزه ای ستون های بتنی تقویت شده توسط خاموت ها - الزویر 2018

abstract

To understand the seismic behaviors of concrete columns confined by corroded stirrups, low-reversed cyclic loading tests were carried out on eight corroded reinforced concrete columns to study their mechanical characteristics and failure mechanisms. The influence on seismic performance indicators such as bearing capacity, hysteresis characteristics, ductility, strength degradation, stiffness degradation, and energy dissipation was analyzed comparatively based on parameters such as stirrup diameter and stirrup-spacing changes. The experimental results showed that the restraint of concrete provided by corroded stirrups is reduced, which leads to a decline in seismic performance, and with increasing stirrup corrosion, the failure limit displacement of columns decreases. The pinch phenomenon of the hysteresis curve gradually increases, the attenuation degree of strength and stiffness increases, and the ductility and energy-dissipation capacity is reduced, while the accumulated energy increases under the same control displacement. A method for predicting the lateral strength of reinforced concrete columns confined by corroded stirrups is presented based on the axial-shear-flexure interaction approach for conventional concrete columns, with modifications to consider the effect of stirrup corrosion. There was good agreement is achieved between the test results and theoretical values.

5. Conclusions

Through the low-reversed cyclic loading test of concrete columns confined by corroded stirrups, a contrast analysis of the failure process, the failure pattern, hysteresis performance, and energy-dissipation capacity has been carried out, leading to the following conclusions. (1) Due to the effect of corrosion on bonding enhancement between the reinforcement and concrete, the seismic performance of the concrete column is not degraded but improved when stirrup corrosion is slight. (2) When stirrups suffer serious corrosion, the confinement effect on the core concrete and transverse reinforcement is weakened, the seismic behavior of the columns is reduced, and the damage feature points that appears in the process of destruction is advanced. Meanwhile, the failure mode gradually changes from ductile failure to brittle failure as the weight loss of the stirrups increases. (3) With the increasing weight loss of the stirrups, the ductility and total energy-dissipation capacity of reinforced concrete columns decreases, and the degree of decline is related to the degree of confinement of the corroded stirrup. The greater the degree of confinement of a concrete column by stirrups, the greater is the degree of degradation of the ductility coefficient and total energy-dissipation capacity after stirrup corrosion. (4) For concrete columns confined by seriously corroded stirrups, the amount of energy dissipation and cumulative energy dissipation is greater than for RC-1 under the same control lateral displacement in the elastic-plastic stage. (5) A lateral strength-prediction method is proposed for reinforced concrete columns confined by corroded stirrups. There is good agreement between the test results and theoretical values.