Steel pipe from the stress-free vibration of concrete under axial compression column design theory 

Abstract: steel concrete structure can give full play to the role of steel and concrete of the two materials with superior mechanical properties. Concrete filled with steel pipe, uniform, dense, will affect the mechanical properties of concrete filled steel tube, thereby affecting the safe use of the entire structure. How to ensure the construction quality of the core concrete construction problems, accidents arising from poor quality of the core concrete construction. Normal concrete shrinkage in the hardening process, reduce the constrained role of the steel pipe. In addition, continuous loads, concrete creep causes the steel pipe stress gradually increased,Mild Steel Pipe the stress will cause the steel pipe local damage to a certain extent. p>
The self-stressing concrete and concrete filled steel tube used in self-compacting concrete technology, the use of self-compacting concrete mobility without segregation of characteristics, to ensure the uniformity and density of the core concrete, to overcome the difficulties of the arch and long-column construction. Volume expansion in the hardening process of self-stressing concrete core concrete under the constraints of the tubes before loading in the three compression loading process steel lateral restraint role into full play, making the steel pipe from the stress of concrete mechanical properties as compared with ordinary steel pipe concrete increased. Previous studies have shown that the self-stressing concrete expansion deformation and stress can be long-term stability, which means that in the pipe, pouring of self-stressing concrete can be completely avoided ordinary concrete due to shrinkage of the binding effect to reduce the problem; the same time, the use of loads significantly less than that of ordinary concrete under the stress of concrete creep and creep, steel pipes and long-term strain from the stress of core concrete coordination, to ensure that the steel pipe bearing capacity of self-stress concrete long-term stability. p>
Through experiments and theoretical analysis to study the deformation and mechanical properties of steel pipe from the stress compacting concrete columns, mainly in the following areas: p>
A test, time-varying pattern of early self-stressing concrete mechanical properties and swelling deformation. The experiments show that: the use of sulphoaluminate self-stressing cement co-ordination of self-stressing concrete, can be prepared by adjusting the self-compacting the self-stressing concrete. The sulphoaluminate self-stressing concrete early strength development is very fast, one day compressive strength can reach 50% in 28 days or more, the elastic modulus of more than 80% in 28 days. Under the constraints of the steel pipe, the initial lateral stress from the stress of concrete up to 3 ~ 6MPa. Computational analysis found that the creep deformation and elastic deformation can be accounted for approximately 2/3 of the effective free expansion and deformation, both part of the deformation can not be ignored in the Carbon steel pipe calculation; The calculation of the effective free expansion mode of creep deformation changes with age of formula. On this basis, through regression analysis of the relationship between the different ratio of the steel under the conditions of limited expansion and deformation and the effective free expansion and deformation calculation results with the experimental results. Can calculate the various age formula is derived limit expansion and deformation types with limit expansion and deformation rate of steel, according to the internal force equilibrium conditions can be the initial value since the stress. p>
Steel tube axial compression of self-stressing concrete short columns test the impact of the initial self-stress on mechanical properties. The strength grade of concrete, steel ratio, since the stress level and other factors on the ultimate bearing capacity of Testp>
Key words: self-stressing self-compacting concrete filled steel tube change from the stress levels Xup>
[Degree-granting units: Dalian University of Technologyp>
[Degree level: Dr site:>
[Degree-granting Year: 2006p>
【Key Words】: TU398.9