Experimental and Numerical Analysis of Battened Built-up Lightweight Concrete Encased Composite Columns subjected to Axial Cyclic loading

R Thenmozhi,N Divyah,M Neelamegam

doi:10.1590/1679-78255745

Abstract

In the recent era, built-up columns have been continuously used by the engineers in the design and analysis of tall buildings and bridges. Vibration analysis of these types of columns is essential to understand the failure modes of such columns. In that aspect, this study aims to analyze a concrete-encased built-up column made by configuring cold-formed steel angle sections connected by means of battens encased by normal weight and lightweight concrete with and without the inclusion of basalt fibre. Eight columns with battens were simulated, and it is encased with four different types of concrete and subjected to axial cyclic loading. The experimental results were correlated with the numerical investigation performed using FEA. The results indicated that the type of concrete dramatically influences the behaviour of columns. Higher ultimate strength and ductility was observed for all specimens, which is due to lower shear capacity of the battens. It was observed that the intensity of the axial cyclic load has a significant effect on the ultimate strength and deflection of columns, but it is less influential on the yield strength. It was concluded the results of experimental and FEA shows good compatibility between each other and depicts an error of 7.48%.

Highlights

The steel-concrete composite columns are not well pronounced for its behavioural aspects as conventional reinforced columns, due to traditional separation between-steel and concrete
The difference in codal provisions for concrete-encased composite columns proves to be a proof for such conflicts
A battened built-up column is a one-type compression member consisting of two identical longitudinal elements separated by a small distance and connected to each other by means of battens at some predefined spacing

Summary

Introduction

The steel-concrete composite columns are not well pronounced for its behavioural aspects as conventional reinforced columns, due to traditional separation between-steel and concrete. The difference in codal provisions for concrete-encased composite columns proves to be a proof for such conflicts. The codes governing reinforced concrete design provides sufficient ductility and the concrete is well confined (Muguruma et al, 1991). The inadequate codal provisions on confinement effects of reinforced concrete and encased composite columns are always uncertain (Collins et al (1993). Numerous researches are in progress in steel-concrete built-up columns to identify precisely the behaviour of such members under various loading conditions. A battened built-up column is a one-type compression member consisting of two identical longitudinal elements separated by a small distance and connected to each other by means of battens at some predefined spacing. The axial buckling strength of these columns are low due to increased shear deflections or due to compound buckling (Duan L, Reno M, Uang C.(2002) when compared to solid columns

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