Slender waist software#
Slender waist series#

Bi-axial stress state of steel tube was considered for failure modelling of steel. A modified stress-strain model was used to capture the constitutive behaviour of confined concrete. CFSTAs were modelled using fibre section beam-column elements available in OpenSees.

Slender waist software#

Numerical modelling was carried out using open-source finite element (FE) software OpenSees. This paper presents a simple yet accurate numerical modelling approach to predict the behaviour of CFSTAs considering in-plane instability failures.

While some of the existing numerical models are able to capture the constitutive behaviour of the materials in CFSTAs accurately, they are computationally expensive to be used for studying the effect of key parameters affecting the CFSTA behaviour. Numerical modelling approaches are favoured in studying the instability failures of concrete-filled steel tube arches (CFSTAs) due to the complexity and high cost of experimental testing of such structural members. Finally, based on the limit equilibrium theory, the suggested formula is given in this study to predict the ultimate axial capacity of these new shaped hybrid columns. The numerical modelling approach for the proposed CFST columns is elaborated and validated by comparing with the test data. The axial load-bearing capacity can significantly improve by pasting FRP on the surface at the middle position of the column. It can be found from the failure mode of the slender-waist shaped columns that the middle section is still the weakest. And the local inward buckling of the outer steel tube is suppressed by the infilled concrete, leading to a very ductile response.

Compare with traditional CFST columns, the slender-waist shaped CFST has a longer elastic stage and its lateral confinement pressure is activated earlier. The test results demonstrate that the core concrete of novel columns is effectively confined by the steel tube.

Slender waist series#

A series of axial compression tests on newly proposed stub columns are carried out. A novel slender-waist shaped CFST is proposed in this study, with the shape of the outer steel tube smaller in the middle section and larger in both end sections. Due to the transverse expansion speed of the steel in the elastic stage is greater than that of the concrete, the confinement hysteresis effect will occur in the concrete-filled steel tube (CFST) under axial loading case.