دانلود رایگان مقاله انگلیسی عملکرد لرزه ای اتصالات داخلی بتنی ستون میله ای با الحاق فولاد T-section تحت بارگیری چرخان - اشپرینگر 2018

Abstract:

An experimental investigation was conducted to study the performance of precast beam-column concrete connections using T-section steel inserts into the concrete beam and joint core, under reversed cyclic loading. Six 2/3-scale interior beam-column subassemblies, one monolithic concrete specimen and fi ve precast concrete specimens were tested. One precast specimen was a simple connection for a gravity load resistant design. Other precast specimens were developed with different attributes to improve their seismic performance. The test results showed that the performance of the monolithic specimen M1 represented ductile seismic behavior. Failure of columns and joints could be prevented, and the failure of the frame occurred at the fl exural plastic hinge formation at the beam ends, close to the column faces. For the precast specimens, the splitting crack along the longitudinal lapped splice was a major failure. The precast P5 specimen with double steel T-section inserts showed better seismic performance compared to the other precast models. However, the dowel bars connected to the steel inserts were too short to develop a bond. The design of the precast concrete beams with lap splice is needed for longer lap lengths and should be done at the beam mid span or at the low fl exural stress region.

7 Conclusions

The experimental results of a research study on the seismic behavior of precast concrete connections designed for earthquake resistance are presented herein. Six beam-to-column subassemblage frames were tested under cyclic loading to observe the hysteresis behavior and seismic performance of these connections. The following conclusions are drawn: The monolithic specimen represented seismic behavior very well. The column and joint failure was prevented by forming a potential plastic hinge at the beam ends, close to the column faces. Shear capacity, ductility, energy dissipation and stiffness degradation were very well obtained seismic parameters.

- For specimens P1-P4, the splitting crack was a major failure mode in the precast specimens. At the joint region, the top reinforcement composed of a longitudinal lapped splice with high strength non-shrink grout concrete was the weakest point. The crack developed along the splice length at the top of the precast beam section. This led to both slippage and bond degradation of the overall frame specimens.

- The maximum strength of all precast specimen was lower than the expected maximum strength because the splitting cracks along the splice length in the high strength non-shrink region appeared.

- The splitting cracks in the high strength nonshrink region resulted in the dramatic degradation of story shear capacity after peak loading.