Thermal numerical analysis of steel and steel and concrete composite columns in a fire situation aimed at the evaluation of the simplified method of ABNT NBR 14323:2013

Abstract

The design of steel and steel and concrete composite columns in a fire situation is directly linked to the reduction of strength and stiffness, among other properties, which are manifested in response to rising temperatures. The normative codes that deal with the design of these elements under the action of fire consider the thermal action based on heating on the four faces of the column, an aspect that does not cover most cases in buildings due to the presence of walls. In this context, given the importance of the correct determination of the thermal field for design purposes, as well as given the simplification adopted by the normative codes, the present work deals exclusively with a study basically aimed at obtaining a representative thermal field for purposes of thermo-structural verification of steel and steel and concrete composite columns. With the focus on the analysis of cases that differ from the prescribed configurations in standards, purely thermal numerical models are proposed, validated through experimental results, whose analyses show an evident reduction in temperature in the steel column when encased with concrete, and with even greater evidence when additionally inserted into walls as a compartmentalizing element. To verify the simplified method proposed by ABNT NBR 14323: 2013, comparative analyses between the numerical thermal fields and obtained by the standardized model were carried out for steel and steel and concrete composite cross sections. For the isolated steel columns, as expected, the normative method proved to be consistent, but conservative when it came to columns inserted into walls. In relation to the composite columns, the results obtained indicate the need for adjustment in the standards for purposes of determining the thermal field and, consequently, of design these elements.

Experimental and Numerical Analysis of Thermo-Mechanical Behaviour of Glass Panes Exposed to Radiant Heating

“…Due to the rapidly increasing computational power of computers and the availability of advanced software tools, the application of numerical analysis methods in fire-related investigations has become very popular in the recent year for various materials and feature types, see e.g., ref. [19][20][21][22]. Among the intrinsic advantages of numerical tools and techniques that can support structural design and research investigations, the reliable thermo-mechanical characterisation of glass and related materials under thermal exposure can represent a critical step for predictions about structural performance.…”