Critical temperature evaluation for steel column exposed to fire – Rankine–Merchant approach

Chemical Degradation of Refractories—An Iterative Thermodynamic Simulation Framework for Corrosion

In the field of refractories, service conditions—often involving high temperatures and extended duration—make the systems more likely to evolve according to the thermodynamics laws. In steelmaking ladles, the chemical degradation of the refractory lining is a critical factor determining its performance and durability. This work revisits the application of thermodynamic to explain the chemical resistance of Al2O3–MgO–C (AMC) refractories used in ladles by the introduction of an iterative thermodynamic simulation framework to cover both oxidation and slag corrosion behavior, demonstrating it as a powerful analytical tool. In contrast to the most common thermodynamic calculations, the iterative method consists in successive calculations, each of them using critical data from the previous one, in order to simulate how the corrosive process proceeds and ends. Four different bricks were studied under distinct high‐temperature conditions in order to assess two processes: oxidation by air and slag corrosion. The analysis focuses on linking the thermodynamic data with experimental indicators to validate the explanatory/predictive power of the simulation models. The simulation for slag corrosion successfully predicted the resistance ranking of all materials while the oxidation model offered a consistent explanation for the materials behavior, related to the graphite consumption, for three of the four AMC bricks. The thermodynamic simulation correctly identified that higher MgO content leads to the lowest slag corrosion resistance, while the presence of Si antioxidant significantly reduces the sensitivity to the atmospheric oxygen attack. The findings demonstrate that the proposed iterative thermodynamic simulation is a time‐saving, and cost‐effective method for anticipating wear resistance and optimizing refractories design, although its reliability depends on the effect of dismissed factors such as the materials’ texture. This approach directly contributes to increasing resource efficiency and promoting more sustainable practices in the steelmaking industry.

A unified design method for concrete-filled composite columns under fire exposure

Concrete-filled double steel tubular (CFDST) columns possess higher fire resistance than concrete-filled steel tubular (CFST) and double-skin CFST (DCFST) columns. However, there is a lack of a simple and practical fire design method for such concrete-filled composite (CFC) columns. This paper proposes a unified method for the design of CFC columns exposed to fire, including CFDST, CFST, and DCFST columns. The unified method is developed based on the Rankine approach, in which the temperature-dependent sectional resistance, Euler buckling load, global buckling reduction, and loading eccentricity effect are consistently incorporated. A total of 474 finite element models were developed using Abaqus to simulate the fire behavior of CFDST columns. A new buckling curve for CFDST columns is derived from Rankine's theory. The buckling coefficients are calibrated by the finite element analysis results. A parameter is proposed to account for the influence of loading eccentricity on the column behavior. Furthermore, a MATLAB-based post-processing program is developed to monitor the temperature evolution of CFC columns. The average temperatures are calculated to approximate the temperature fields in a composite column. The accuracy of the proposed unified method is validated by 118 experimental results and 1040 finite element simulations of CFC columns exposed to fire. The unified method is shown to be an accurate and efficient tool for practical design of CFC columns under fire exposure.

Nonlinear buckling and post-buckling response of steel trusses under localized fire exposure

This paper develops a nonlinear finite element framework for buckling and post-buckling of steel dome truss - es under combined mechanical loads and non-uniform temperature fields from localized fires. A weak coupling sequential strategy using McCaffrey’s plume model with Gaussian lateral distribution determines the temperature field, which is then mapped onto the structural model. Fire location is parameterized by polar coordinates . The Updated Lagrangian (UL) formulation accounts for large displacements, thermal expansion, and temperature-dependent degradation of steel properties per Eurocode 3. The generalized displacement control (GDC) method traces full equilibrium paths. Validation against published results shows good agreement. Parametric study on an S275 steel truss under five fire scenarios (FS1–FS5) reveals that a fire at the dome center (FS1) increases the criti - cal load by up to 109% due to arching, while a fire at the boundary (FS5) reduces it by approximately 4% – the most hazardous scenario. Elastoplastic analysis consistently yields lower critical loads than elastic analysis. These findings provide practical guidance for performance-based fire design of large-span steel dome trusses, highlight - ing that fires near the boundary are more dangerous than those near the center.

Finding a generalized compaction model for 19 oedometric tests on granular salt

The time required to compact initially loose granular salt into an impermeable backfill body, for example for the final disposal of radioactive waste in salt formations, is foremost determined by the on-site rate of cavity convergence. However, this rate decreases with the increasing load resistance of the salt backfill, which, in turn, is controlled by a range of complex interacting factors, whose relative contributions have not yet been fully quantified. Hence, forecasting when a backfill body will reach its impermeable compaction state is still challenging. In this empirical approach, we re-evaluate 19 oedometric compaction tests, in which the increase of backfill resistance was experimentally determined for varying boundary conditions. We show to what extent the increase varies across all experiments and highlight how this variation correlates with the deliberately varied test conditions. To this end, polynomial prediction models of varying degrees were fitted for each test. Based on the adjusted coefficient of determination $$ \left({R}_{adj}^2\right) $$, a fourth-degree polynomial was found to provide the best representation of the observed variability within the data $$ \left({R}_{adj}^2=0.27\right) $$. When fitting prediction models based on data grouped by compaction rate the mean adjusted R 2 improves over all groups to 0.67 leading to a more precise estimation of the underlying data and provides a promising outlook to eventually extrapolate for in-situ compaction rates. Further data grouping seems valuable if additional tests (1) allow a well-maintained moisture content throughout the test duration and (2) expand the value range and distribution for temperature, grain size and material type.

Numerical Analysis and Design for Residual Patch-Loading Resistance of S690 HSS Corrugated Web I-Girders Subjected to Elevated Temperatures

A Critical Review of Full-Scale Fire Tests and Prediction Methods for Timber–Concrete Composite Slab Floors

With growing demand on low-carbon and fire-safe building solutions, timber–concrete composite (TCC) floors have emerged as a sustainable and efficient alternative. This paper provides a critical review of the fire performance of slab-type TCC floors, with an emphasis on studies reported in the past five years, including 25 full-scale furnace tests. Results show that cross laminated timber (CLT) concrete floors are prone to char fall-off, leading to sharp inner temperature rises and highly variable fire resistance (30–214 min), mainly influenced by load ratio, lamella thickness, and connection type. The fire resistance of slabs generally exceeded 90 min under service loads, and higher load ratios caused earlier failure. By contrast, nail-laminated timber– and laminated veneer lumber–concrete systems exhibited stable charring and consistently higher resistance ( > 190    min ). Emerging simulation approaches that model char fall-off and temperature-dependent connector degradation show improved agreement during extended fires, though broader validation is still needed. Simplified analytical methods, such as the γ -method, provide useful estimates but require calibration across load levels. Future research should refine delamination modeling, incorporate temperature-dependent connector behavior, and recalibrate analytical methods using full-scale data to ensure reliable fire design of TCC floors.