Abstract
To explore the influence of the applied axial compression ratio and preloaded axial compression ratio on the seismic performance of unbonded prestressed concrete columns, pseudo‐static tests were carried out on four prestressed columns and one ordinary column in this study. The seismic performance indexes of test columns were studied and analyzed, including failure modes, hysteresis curves, skeleton curves, stiffness, ductility, and energy dissipation. The test results show that compared with concrete columns with ordinary reinforcement, the hysteresis curve of reinforced concrete columns with prestressed tendons has a pinch phenomenon to a certain extent, and the energy dissipation performance becomes worse. For the prestressed columns, the greater the applied axial compression ratio, the worse the fullness of hysteresis curves and the energy dissipation performance, the greater the residual displacement, the faster the strength attenuation, and the worse the self‐centering performance. For the posttensioned unbonded prestressed concrete columns, the greater the preloaded axial compression ratio, the worse the energy dissipation performance of the test column, the slower the strength attenuation, and the better the self‐centering performance.
Highlights
Regardless of the axial compression ratio, the greater the loading displacement of each test column, the greater the equivalent damping coefficient; the larger the applied axial compression ratio and preloaded axial compression ratio of each test column, the smaller the equivalent damping coefficient. It shows that the increase in the applied axial compression ratio and the preloaded axial compression ratio leads to the deterioration of the energy dissipation capacity of the column
The low-cycle repeated loading tests were conducted on one ordinary reinforced concrete column and four reinforced concrete columns with posttensioned unbonded prestressed tendons under different axial compression ratios. e conclusions are obtained as follows: (1) Adding posttensioned unbonded prestressed tendons to ordinary reinforced concrete columns can lead to poor energy dissipation performance, but it can effectively improve the self-centering performance of the test columns and reduce the residual displacement of the columns
(2) Axial compression ratio is an important factor affecting the seismic performance of test columns
Summary
In this test, four concrete columns with posttensioned unbonded prestressed tendons (marked as PURC) and one ordinary reinforced concrete column (marked as PTRC) were designed and fabricated in the proportion of 1/2. E size of the prestressed members used in this test was smaller than that in the actual project; the reduction in length can cause a large amount of prestress loss [14] To solve this problem, a support foot device developed by the China University of Mining and Technology was used to supplement the tension by the insert gasket [15]. E loading system was as follows: the yield displacement Δ of each test column was obtained by the load control with an increase of 10 kN. When the load dropped below 85% of the maximum load value, the specimen was considered to be destroyed and the test was terminated
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