دانلود رایگان مقاله انگلیسی تحقیق در مورد رفتار لرزه ای و مقاومت برش ستون های فریم SRHC - اشپرینگر 2017

Abstract:

The seismic behavior of steel reinforced high strength and high performance concrete (SRHC) frame columns was investigated through pseudo-static experiments of 16 frame columns with various shear span ratios, axial compression ratios, concrete strengths, steel ratios and stirrup ratios. Three kinds of failure mechanisms are presented and the characteristics of experimental hysteretic curves and skeleton curves with different design parameters are discussed. The columns’ ductility and energy dissipation were quantitatively evaluated based on seismic resistance. The research results indicate that SRHC frame columns can withstand extreme bearing capacity, but the abilities of ductility and energy dissipation are inferior because of SRHC’s natural brittleness. As a result, the axial load ratio should be restricted and some construction measures adopted, such as increasing the stirrup ratio. This research established effect factors on the bearing capacity of SPHC columns. Finally, an algorithm for obtaining ultimate bearing capacity using the fl exural failure mode is established based on a modifi ed planesection assumption. The authors also established equations to determine shearing baroclinic failure and shear bond failure based on the accumulation of the axial load force distribution ratio. The calculated results of shear bearing capacity for different failure modes were in good agreement with the experimental results.

5 Conclusions

Based on the low-cycle repetitive loading test and theoretical analysis of the SRHC frame columns, the following conclusions can be generalized: (1) All seismic performance indexes of SRHC frame columns designed properly are adequate and can be applied in engineering practice. However, due to the natural brittleness of HSHPC, their ductility and energy dissipation capacity are inferior to those of ordinary SRC frame columns. Therefore, the axial compression ratio should be strictly limited, and some construction strengthening measures such as increasing stirrups should be adopted. (2) As the shear span ratio increases, the failure modes of the specimens subjected to the compound action of compression, bending and shearing are ordinal shearing compression failure, shearing splitting failure and fl exural failure, and the horizontal bearing capacity decreases gradually but the rate of deterioration slows down after the maximum horizontal load. The ductility and energy dissipation capacity is gradually enhanced. (3) As the concrete strength and axial compression ratio heighten, the horizontal bearing capacity increases gradually but the rate of decay increases after the maximum horizontal load. The ductility and energy dissipation capacity reduce gradually. (4) When the stirrup ratio and steel ratio grow, the horizontal bearing capacity increases gradually, and the rate of deterioration slows down. The ductility and energy dissipation capacity intensifi es gradually. (5) The calculation method proposed for shear bearing capacity of SRHC frame columns in different failure modes is reasonable and its corresponding expressions are accurate; hence, they can be applied to engineering design.