This dissertation aims at understanding the behaviour of circular concrete-filled steel tubular members and finding a proper simplified numerical model for modelling this type of structural members under lateral loading or lateral loading... more
This dissertation aims at understanding the behaviour of circular concrete-filled steel tubular members and finding a proper simplified numerical model for modelling this type of structural members under lateral loading or lateral loading combined with axial load. Two numerical models are investigated, namely detailed 3D numerical modelling using the software ABAQUS and 2D numerical modelling with distributed plasticity approach using the software OpenSees. Both finite element models are validated by comparing the results with experimental test data. The detailed 3D numerical model has shown to be accurate in predicting the behaviour of circular CFST columns while the 2D numerical model using OpenSees with uniaxial material properties always underestimates the lateral capacity of the members. Prior research studies attributed this difference to enhancement of concrete properties due to the confinement effect of steel tube on the concrete core. It is shown in the 2D numerical results that even by accounting for confinement effects, using several proposed confined concrete models available in the literature, there is still underestimation of the lateral capacity of circular CFST members. Detailed 3D numerical models show that this over-strength in the ultimate lateral capacity of circulars CFST members is attributed not only to the concrete confinement effect but also to the change of steel properties due to the bi-axial stress state developing in the steel tube. Finally, a simplified 2D numerical model using OpenSees with modified material properties based on 3D models is suggested and validated through comparison with experimental results. Keywords: circular concrete filled steel tubes; rubberized concrete; simplified numerical model; distributed plasticity; bi-axil stress state; over-strength
Growing construction activities requires increase in construction materials. The conventional method of constructions results in a rise in construction waste. Formwork as a main factor to generate construction waste has been the topic of... more
Growing construction activities requires increase in construction materials. The conventional method of constructions results in a rise in construction waste. Formwork as a main factor to generate construction waste has been the topic of investigation. The permanent formwork has been introduced with the aim to: promote the construction technology process that put quality, safety and environment issues into account, reduce the cost of workers and reduce the overall time of construction project. At present the permanent formwork available in the market are made from steel, and plastic and the cost is still high. Therefore this study is looking at the potential of commercial wood-wool cement board (WWCB) as permanent formwork. A series of concrete columns were constructed with and without integrated WWCB with different configurations of WWCB as permanent formwork. These columns were subjected to axial load and the compressive strength and failure modes were recorded. The results show that the present of permanent formwork from WWCB improves the compressive strength of the column. With the permanent formwork, the size of concrete column can be reduced and able to support the same load as column without permanent formwork. Therefore this construction method can reduce the overall cost of construction.
This paper presents a finite-element (FE) analysis of hybrid fiber-reinforced polymer (FRP)-concrete-steel double-skin tube (FSDT) in the form of columns. The FSDT columns that were examined consisted of a concrete wall sandwiched between... more
This paper presents a finite-element (FE) analysis of hybrid fiber-reinforced polymer (FRP)-concrete-steel double-skin tube (FSDT) in the form of columns. The FSDT columns that were examined consisted of a concrete wall sandwiched between an outer FRP tube and an inner steel tube. A FE software was used to develop a pushover analysis of three-dimensional FSDT models to simulate seismic loading. The FE models were validated against the experimental results gathered from seven FSDT columns tested under cyclic loading. The FE analysis results were in good agreement with the experimental backbone curves. The maximum error was 9% in predicting the bending strengths of the columns. Aparametric study evaluated the effect of axial load level, concrete wall thickness, concrete strength, diameter-to-thickness ratio (D=t) of the steel tube, and number of FRP layers on the FSDT columns’ behavior. This study revealed that the behavior of FSDT columns is quite complex. It also revealed that this behavior is controlled by the interactions that occur among the steel tube’s stiffness, the concrete wall’s stiffness, and the FRP hoop’s stiffness. Local buckling occurred in all of the specimens examined. This buckling caused the FSDT system to rupture. Two modes of failure were defined as follows: (1) steel/concrete compression failure, and (2) FRP rupture. Compression failure was relatively gradual whereas failure due to FRP rupture was quite abrupt. Finally, the bending strength increased as the applied axial load, concrete compressive strength, and number of FRP layers increased. The bending strength also increased as both the concrete wall’s thickness and the D=t decreased.
"Proceedings of the sixth International Conference on Composite Construction in Steel and Concrete held at the Devil’s Thumb Ranch in Tabernash, Colorado, July 20–24, 2008. Sponsored by Engineering Conferences International; the... more
"Proceedings of the sixth International Conference on Composite Construction in Steel and Concrete held at the Devil’s Thumb Ranch in Tabernash, Colorado, July 20–24, 2008. Sponsored by Engineering Conferences International; the Structural Engineering Institute of ASCE.
This collection contains 63 technical papers representing the state-of-the-art in composite construction worldwide.
Topics include:
+ composite bridges,
+ composite slabs,
+ shear connectors,
+ composite columns,
+ innovative composite structural systems,
+ fire and seismic resistance of
composite structural systems, and
+ practical applications.
These papers will be valuable to structural engineers and allied professionals engaged in construction with steel and concrete composites.
"
... Seismic Multi-Axial Behavior of Concrete-Filled Steel Tube Beam-Columns Tiziano Perea Roberto T. Leon Georgia Institute of Technology Atlanta, Georgia August 14, 2009 Page 2. Introduction NEESR-II: System Behavior Factors for... more
... Seismic Multi-Axial Behavior of Concrete-Filled Steel Tube Beam-Columns Tiziano Perea Roberto T. Leon Georgia Institute of Technology Atlanta, Georgia August 14, 2009 Page 2. Introduction NEESR-II: System Behavior Factors for Composite and Mixed Structural Systems ...
