Study On Precast Concrete Pipe Column

Precast concrete pipe column is constructed by pouring concrete into precast pipe column, which acts as mould as well as resists loads with concrete pouring in site. Precast concrete pipe column, as a kind of resistance member of buildings, is a kind of standardized production with high quality, and has a high bearing capacity as the utility of high strength concrete. Its construction process is effective under assembly process, and without secondary decoration by adopted as cast finish concrete. It can be widely used and has a low cost as low quantity of mould and steel is applied.On the basis of current research on constitutive model of concrete and reinforcement and their interaction, taking into account of theory concerning constrain on concrete by reinforcement and concrete damage, numerical model concerning elastoplastic damage model and nonlinear behavior was developed using FEM software ABAQUS, in order to study on the resistance capacity and deflection of precast concrete pipe short column. Formulation and its simplified vision concerning ultimate resistance capacity of precast concrete pipe short column were developed. The compressive strength and corresponding ultimate strain and stress-strain diagram of core concrete was proposed. It is concluded that the value of the simplified enhanced coefficient of resistance capability is between 1.05and 1.3. Among the three factors of wall thickness, stirrup characterize value, stirrup spacing that affect resistance capability, stirrup characterize value has the most significant impact, and wall thickness, stirrup spacing have the secondary impact. The ultimate resistance capability of short column increases by 10%~40%,10%~30%,10%~20%,10%~30% as the increase of core concrete strength ,the increase of stirrup ratio, the increase of wall thickness ,and the decrease of stirrup spacing separately. The compressive strength of the core concrete increases by 20%~60%,20%~50%,5% as the increase of stirrup ratio ,the increase of wall thickness and the decrease of stirrup spacing separately, but the increment decreases gradually. The ultimate strain increases as the increase of stirrup ratio, the increase of wall thickness, and the value was between 0.002and 0.004. The stress-strain diagram of core concrete obtained was in accordance with current research result.It is indicated that from the research the resistance capability of medium long column (the slenderness ratio is less than 20) is similar to that of short column, and there is no lateral deflection in the column. The transverse stain was 0.3~0.5 times of longitude stain, that is to say the calculation Passion's ratio is 0.3~0.5. The resistance capability-moment relationship of beam-column was in accordance with the axial force-moment diagram obtained by current calculation method, but the resistance capability increases by 20%. The initial eccentric was taken into account when the slenderness ratio is 30, and the effect of second-order effects is notable.Taking into account of quasi-static experiment method and damage factor, the ultimate displacement of short column is 30~40mm, 60~80mm, and the resistance capability of short column is 30~40kN, 135~145kN when axial compression ratio of short column is 0, 0.2 separately under monotonous transvers loads. The data above are 20%, 25%, 25%, and 30% larger than that corresponding data of precast concrete hollow pipe separately. And the ductility factors are all bigger than 6 under different conditions. Under cyclic loadings, the hysteresis loop obtained is full and spine curve is in good condition, and the ratio of strength degradation is between 0.95~0.98.