Reliability Analysis of RC Beams Exposed to Fire

Abstract

A procedure for conducting reliability analysis of reinforced concrete beams subjected to a fire load is presented. This involves identifying relevant load combinations, specifying critical load and resistance random variables, and establishing a high-temperature performance model for beam capacity. Based on the procedure, an initial reliability analysis is conducted using currently available data. Significant load random variables are taken to be dead load, sustained live load, and fire temperature. Resistance is in terms of moment capacity, with random variables taken as steel yield strength, concrete compressive strength, placement of reinforcement, beam width, and thermal diffusivity. A semi-empirical model is used to estimate beam moment capacity as a function of fire exposure time, which is calibrated to experimental data available in the literature.The effect of various beam parameters were considered, including cover, beam width, aggregate type, compressive strength, dead to live load ratio, reinforcement ratio, support conditions, mean fire temperature, and other parameters. Using the suggested procedure, reliability was estimated from zero to four hours of fire exposure using Monte Carlo simulation. It was found that reliability decreased nonlinearly as a function of time, while the most significant parameters were concrete cover; span/depth ratio when axial restraints are present, mean fire temperature; and support conditions.

Reliability-based evaluation of the inherent safety presumptions in common fire safety design

“…Sidibé et al investigated the reliability of concrete columns exposed to the ISO 834 standard fire curve [7], while Wang et al [8] and Eamon and Jensen [9,10] used an analytical formulation to assess the reliability of concrete beams. Recently, Guo et al [11] presented a framework for assessing the reliability of structural elements, taking into account an uncertain fire load, and Van Coile et al proposed an easy-to-use reliability-based framework for assessing the residual load bearing capacity after fire exposure [12].…”

Towards a reliability‐based post‐fire assessment method for concrete slabs incorporating information from inspection

“…In recent years, numerical tools and finite element models have been developed for analysing the performance of concrete structures during fire exposure [2][3][4][5]. Some studies have even investigated the reliability of structural elements during fire exposure [6][7][8][9], ultimately allowing, for example, optimization of the design by balancing upfront investments in safety with a reduced probability of failure during the lifetime of the structure [10]. However, few studies focus on the residual structural capacity after fire exposure (see [11,12], for example), and to the best of the authors' knowledge, no userfriendly method for assessing the maximum service load after fire exposure has been proposed.…”

Complex and comprehensive method for reliability calculation of structures under fire exposure

“…Their results showed among others the effect of live load ratio, concrete cover, reinforcement ratio and the type of fire curve on the structural reliability. In other studies [12,13] they presented the reliability analysis of reinforced concrete columns and conventional beams. Colie et al [14] analysed simple supported one-way concrete slabs using ISO standard fire model.…”