Influence of fire-resistant coating on the physical characteristics and residual mechanical properties of E350 steel section exposed to elevated temperature

Abstract

PurposeMost of the industrial buildings which are designed to moderate loads are constructed using light gauge cold-formed steel (CFS) sections. Residual mechanical properties of CFS sections exposed to elevated temperature need to be investigated as it is necessary to predict the deterioration of elements to avoid failure of the structure or its elements. Also, it would be helpful to decide whether the structural elements need to be replaced or reused. The use of fire-resistant coatings in steel structures significantly reduces the cost of repairing structural elements and also the probability of collapse. This study investigates the effect of fire-resistant coating on post-fire residual mechanical properties of E350 steel grade.Design/methodology/approachIn this study, an attempt has been made to evaluate the residual mechanical properties of E350 steel. A tensile coupon test was performed for the extracted specimens from the exposed CFS section to determine the mechanical properties. Four different fire-resistant coatings were selected and the sections were coated and heated as per ISO 834 fire temperature curve in the transient state for time durations of 30 minutes (821°C), 60 minutes (925°C), 90 minutes (986°C), and 120 minutes (1,029°C). After the exposure, all the coupon specimens were cooled by either ambient conditions (natural air) or water spraying before conducting the tension test on these specimens.FindingsAt 30 min exposure, the reduction in yield and ultimate strength of heated specimens was about 20 and 25% for air and water-cooled specimens compared with reference specimens. Specimens coated with vermiculite and perlite exhibited higher residual mechanical property up to 60 minutes than other coated specimens for both cooling conditions. Generally, water-cooled specimens had shown higher strength loss than air-cooled specimens. Specimens coated with vermiculite and perlite showed an excellent performance than other specimens coated with zinc and gypsum for all heating durations.Originality/valueAs CFS structures are widely used in construction practices, it is crucial to study the mechanical properties of CFS under post-fire conditions. This investigation provides detailed information about the physical and mechanical characteristics of E350 steel coated with different types of fire protection materials after exposure to elevated temperatures. An attempt has been made to improve the residual properties of CFS using the appropriate coatings. The outcome of the present study may enable the practicing engineers to select the appropriate coating for protecting and enhancing the service life of CFS structures under extreme fire conditions.

Web-Crippling Capacity of High Performance Cold-Formed Lipped Steel Sections Subjected to Elevated Temperature

“…Notably, the ITF specimen exhibited approximately a 10-15% higher carrying capacity compared to the ETF condition. Similar trends were observed in the previous studies [1,2,23]. At elevated temperatures, the CFS WH and WCH specimens displayed a reduction in web-load-carrying capacities, measuring 13.82 kN, 8.14 kN, 6.58 kN, 4.86 kN and 8.5 kN, 5.8 kN, 3.27 kN, 1.56 kN, for 30, 60, 90, and 120 min, respectively.…”

“…Furthermore, the web strength reduction in CFS specimens was more pronounced in the water cooling compared to air cooling. The cooling of steel specimens with water results in reduced yield strength and ductility due to changes in the microstructure [1]. Therefore, the residual moment carrying capacity of the steel primarily depends on the temperature magnitude, heating duration, and cooling method.…”

“…In recent times, high-performance cold-formed steel (CFS) structures have become increasingly popular in construction practices due to their strength, durability, and versatility of construction. This is primarily due to the several advantages offered by highperformance CFS, including the use of light-gauge sections, innovative profiles of preferable size, high strength-to-weight ratio, requirement of less manpower, and ease of transportation and assembly [1]. Moreover, in various countries, the design standards and guidelines for CFS elements have been well established, thereby increasing the demand for CFS members in construction practices and for other applications [2].…”

Influence of elevated temperature on buckling capacity of mild steel-based cold-formed steel column sections– experimental investigation and finite element modelling

“…The properties of the material used for the analysis of CFS columns were extracted from the temperature-dependent coupon test results (Kumar et al ., 2022). The properties of materials like Young's modulus (E), ultimate stress (fu), yield stress (fy), strain (ε) and Poisson's ratio (v) were defined in the CAE model.…”

The partial fire protection of steel members: a comparative study

“…When excessively large amounts are used, the insulating properties of the spray can deteriorate, and microcracks can form immediately after application of the spray. These cracks enlarge with time and can cause entire sections of the spray to fail (Jaya Kumar et al, 2022;Dai et al, 2022).…”