Nonlinear Finite Element Analysis On Steel Reinforced Ultra High Strength Concrete Structures

With the building structure development to the high-rise and long-span, ultra high strength concrete (UHSC) is more and more widely used. The bearing capability and durability of steel reinforced high strength concrete structures is much better than ordinary concrete structure. Compared with ordinary concrete, the bearing capability and durability of ultra high strength concrete is much better. But with the concrete grade rising, UHSC becomes more and more brittle. It is necessary research on the seismic performance of UHSC. With finite element simulation we can better understand the whole loading process of structural, steel bar, steel shape and concrete. Finite element simulation combined with the test can reduce the financial and human inputs.In this paper, used AN SYS finite element software, analyses the ultra high strength concrete frame columns and frame column joints on the mechanics performance in the low-cyclic reversed loads. In the paper, the author firstly research on the Strain-Stress relationship of UHSC materials, the Failure Criteria and Failure Surface. Then various Failure Models of steel bar, steel shape, concrete are discussed respectively. Used Separate model, finite element models of 12 ultra high strength concrete short columns,13 ultra high strength concrete frame columns,6 ultra high strength concrete frame column joints are established. Ignore the bond between steel and concrete and the bond between steel and concrete slip.Based on high strength concrete columns reinforced and the frame joint experiments, simulate the performance of component in the low-cyclic reversed loads. The hysteretic curves, skeleton curves were obtained. The calculated hysteretic curves and skeleton curves compared with the experiment and found good agreement. The characteristics of the hysteretic performance, the stress development of steel bar; steel shape, concrete in the loading process, the location and trend of crack development, the failure modes of component were analyzed. About the seismic performance of the ultra high strength concrete structures, the impact factors contains the shear span ratio, stirrup ratio and axial compression ratio.