Study On Seismic Performance Of Partially Concrete-filled Steel Circular Cross-section Brigde Piers

Concrete-filled steel tube(CFST) was developed on the basis of steel structure, reinforcedconcrete structure, steel reinforced concrete structure. Concrete-filled steel tube, which has highbearing capacity, good ductility and many other features, is more and more widely used in theproject. However, the concrete-filled steel tube structure in bridge application is not verycommon. Especially Steel tubular bridge piers with partial concrete-filled, is still in the theoreticalphase in the country. With the development of the national economy, the city steel bridge viaductis necessarily the development direction of future urban transport. This paper is based on theresearch and practical application of the box-section steel bridge piers with partial concrete-filledby some developed countries, such as Japan, Europe and the United States. It studies the seismicperformance experiment of twelve circular cross-section steel piers with partial concrete-filled.The parameters of study are mainly considered about the factors of the slenderness ratio, radiusto thickness ratio, concrete strength and concrete-filled height. The purpose of the experiment isto inspect the advantage of partial concrete-filled steel bridge piers compared with steel bridgepiers seismic performance, and to study its strength degradation, stiffness degradation, ductilityand energy dissipation capacity, as well as the effect of seismic performance of steel bridge piersby the built-in concrete-filled height under different parameters.The experiment result shows that the steel bridge piers with partial concrete-filled,compared with steel bridge piers, have superior seismic performance. The carrying capacity willincrease as the partial concrete-filled height increases, but the increase amplitude is at a modestrate. And the hysteretic curve is the more and more full. When the concrete-filled reaches to aceitain height, even though the bearing capacity increases, the carrying capacity and ductilitywill sharply decline as the load deflection increases, the seismic performance turns out to be poor.So I concluded that the optimal built-in concrete-filled rate is between30%and50%. Whenslenderness ratio of the steel bridge piers is relatively small and radius to thickness ratio isrelatively large, the optimal concrete-filled rate takes the maximum within the range. Whenslenderness ratio of the steel bridge piers is relatively large and radius to thickness ratio isrelatively small, the optimal concrete-filled rate takes the minimum within the range.This paper is simulated four steel tubes with partial concrete-filled using ABAQUS finiteelement analysis of bridge piers. On the basis of finite element coincides with the experimentalresults, expanding the parameters analysis and simulating65specimens. The results of analysisshows that,(1) Under the circumstances of different slenderness ratios and other conditionsequally the same, the carrying capacity of simulated specimens will increase as the built-in concrete-filled height increases, but the overall increase of the amplitude is not too large. Theslenderness ratio is the main factor that affects the ductility coefficient. Ductility coefficientdecreases rapidly as the slenderness ratio λ increases.(2) Under the circumstances of differentradius to thickness ratio and the same other conditions, the differences in the bearing capacitiesof different radius to thickness ratio Rtspecimens are greater. The smaller Rtis, the higher thecarrying capacity is. The ductility reduces as radius to thickness ratio Rtincreases. The greaterthe Rtis, the poorer the ductility is, that is the poorer seismic performance.