Fire resistance of partially encased composite columns subjected to eccentric loading

PurposeInvestigate the fire performance of eccentrically loaded concrete partially encased column (PEC), using the advanced calculation method (ANSYS 18.2, 2017) and the simple calculation method in Annex G of Eurocode 4 (EN 1994-1-2, 2005). This work examines the influence of a range of parameters on fire behaviour of the composite column including: eccentricity loading, slenderness, reinforcement, fire rating and fire scenario. In this study, ISO-834 (ISO834-1, 1999) was used as fire source.Design/methodology/approachCurrently, different methods of analysis used to assess the thermal behaviour of composite column exposed to fire. Analytical method named simplified calculation methods defined in European standard and numerical simulations named advanced calculation models are treated in this paper.FindingsThe load-bearing capacity of the composite column becomes very weak in the presence of the fire accident and eccentric loading, this recommends to avoid as much as possible eccentric loading during the design of construction building. The reinforcement has a slight influence on the temperature evolution; moreover, the reinforcement has a great contribution on the load capacity, especially in combined compression and bending. When only the two concrete sides are exposed to fire, the partially encased composite column presents a high load-bearing capacity value.Originality/valueThe use of a three-dimensional numerical model (ANSYS) allowed to describe easily the thermal behaviour of PEC columns under eccentric loading with the regard to the analytical method, which is based on three complex steps. In this study, the presence of the load eccentricity has found to have more effect on the load-bearing capacity than the slenderness of the composite column. Introducing a load eccentricity on the top of the column may have the same a reducing effect on the load-bearing capacity as the fire.

Non-Linear Numerical Modelling of Sustainable Advanced Composite Columns Made from Bamboo Culms

The present article uses the finite element analysis (FEA) software ABAQUS to model a bamboo-based advanced composite column for construction. Different numerical models were analysed to be able to predict the behaviour of a bamboo-based composite column tested by the same group. Bamboo-based composites maintain the inherent excellent mechanical properties of raw bamboo whilst adding a certain degree of processing and engineering. Thus, the composite individual samples are more consistent and reliable when compared with their raw counterparts. A buckling analysis is carried out to determine the response of the composites to axial compressive loading. Different modelling elements and imperfection parameters were implemented separately in different FEA models so that the efficacy of each could be established and suggestions could be made with regard to the modelling elements and size of imperfection that should be used in future models. The results are compared to empirical findings, giving insights into the quality of results that can be obtained using numerical modelling. This also allowed for an evaluation of the methods and assumptions applied in the model. The load at rupture and displacements obtained by the numerical model were comparable to the experimental findings, with only minor differences observed.

Cross-section optimization of thin-walled open-section composite column for maximizing its ultimate strength

This paper focuses on the optimization of thin-walled open cross-section laminated composite column subjected to uniaxial compressive load. The cross-section of the column is parameterized in such a way that it can represent a variety of shapes including most of the regular cross-sections such as H, C, T, and I sections. The objective is to obtain the best possible shape of the cross-section, by keeping a constant total material volume, which can maximize the ultimate load carrying capacity of the column. The ultimate strength of the column is determined by considering both buckling instability and material failure. For material failure, Tsai-Wu composite failure criterion is considered. As analytical solutions for these parameterized column models are not tractable, the ultimate loads of the composite columns are computed through finite-element analysis in ANSYS. And, the optimization is carried out by coupling these finite-element results with a genetic algorithm based optimization scheme developed in MATLAB. The optimal result obtained through this study is compared with an equivalent base model of cruciform cross-section. Results are reported for various lengths and boundary conditions of the columns. The comparison shows that a substantial increase of the ultimate load, as high as 610%, can be achieved through this optimization study. Thus, the present paper highlights some important characteristics of open cross-sections that can be useful in the design of thin-walled laminated column structures.

Effect of Geopolymer Concrete Encased I-Section and Geopolymer CFST Column Under Fire

Geopolymer concrete can resist fire quite well when compared with conventional concrete. Recent studies to observe the behaviour of geopolymer composite column under the effect of fire are very few. In this paper results in terms of stress, strain and deformation of geopolymer composite column expressed to elevated temperature are presented. It was observed that geopolymer composite column performs better at elevated temperatures than the conventional composite column. This tests are performed with four composite column with geopolymer concrete and conventional concrete which is tested at four elevated temperatures i.e., 400 oC, 500 oC, 600 oC, 700 oC and 800 oC to evaluate the strength parameters. It results geopolymer concrete column can be used where fire disaster chances are high.

Evaluation of Stability of Embankment Constructed on Soft Consolidating Soil with Lime–CFG Composite Column System

Effectiveness of providing lime and CFG composite column system on the safety factor of embankment constructed on consolidating soil is studied at different time intervals during consolidation of foundation soil. The effectiveness of providing composite column system is compared with the effectiveness of providing only lime or CFG columns. In addition, the effectiveness of composite column system on settlement of foundation soil and consolidation process is also investigated. Embankment, foundation soil and columns are modeled using finite element method. Numbers of trial surfaces with different center and radius are generated at each time interval and the critical surface is selected to calculate the safety factor using the effective stresses obtained by finite element analysis. From the study, it is concluded that provision of lime or CFG columns, either individually or in combination, reduces the settlement and improves the safety factor. However, the most effective type of columns and their arrangement to reduce the settlement may not be the most effective to enhance the safety factor and hence, the type of columns and their arrangements has considerable influence on the purpose for which columns are provided.

Mechanical Behavior of Silica Fume Concrete Filled with Steel Tubular Composite Column

Recycling or utilization of industrial waste is becoming more popular as people become more environmentally conscious. Silica fume is a by-product of the smelting process in the silicon and ferrosilicon industries. This study examines the mechanical behavior of steel tubular composite column filled with conventional concrete and silica fume concrete experimentally under axial compressive loading. For the study, variability in steel tube thickness and column height with a constant diameter are considered. To explore the influence of silica fume in concrete, microstructural analyses are carried out by SEM, XRD, and FTIR. The experimental results reveal that the use of silica fume as a replacement of cement is feasible; the silica fume concrete-filled steel tubular (SCFST) column has marginal enhancement strength capacity compared to CFST column as thickness increases.