Standard Fire Exposure Research Articles

Experimental study to assess the impact of different connection types on the fire resistance of composite concrete-topped CLT slabs

This paper summarizes the results of an experimental study of fire resistance of composite concrete-topped cross-laminated timber (CT-CLT) slabs exposed to fire at their soffit. Six composite CT-CLT slabs and one untopped CLT slab were tested under ISO 834 standard fire exposure while subject to an applied load equal to 20 % of the slab ultimate capacity. Test variables included the type and configuration of shear connection between the topping and CLT. Large bending deflections were observed as the slabs reached their fire resistance. Although the untopped CLT slab exhibited a fire resistance of only 16 min, all CT-CLT exhibited fire resistance greater than 1 h. The improved behavior is attributed to the stiffer CT-CLT behavior. CT-CLT slabs exhibited delamination of the lowermost layer of the CLT following through-layer charring. Observed charring rates were approximately 46 mm/h. Observed charring depths were well-predicted by existing design standard-recommended equations. Importantly, the interface between the concrete topping and CLT remained close to 30 °C and never exceeded 65 °C in any test. This is a promising result for employing adhesive systems to affect composite behavior between the topping and CLT.

Experimental investigation into the effect of transparent fireproof coatings on charring behavior of glued laminated timber exposed to fire

As timber structures evolve towards greater heights and longer spans for buildings, there is a pressing need to enhance the fire resistance of timber structures. Considering the charring behavior of timber is crucial to the fire resistance of timber structures, it is a promising way to retard the charring behavior of timber and further enhance the fire resistance by applying transparent fireproof coatings. In this study, a series of fire tests were conducted to investigate the effect of transparent fireproof coatings on the charring behavior of Douglas fir glued laminated timber (Glulam) under small-scale ISO 834 standard fire conditions. Different coating types, coating quantities, exposed time to fire and member sizes were considered in the experiments. The experimental results including temperature profiles, maximum temperature, and charring rates for uncoated and coated Glulam specimens were carefully recorded and analyzed. Then, the effect of transparent fireproof coatings was quantified by the proposed ratio of delayed charring. The main mechanism of the delayed charring in fire was finally discussed. This study demonstrated that two transparent fireproof coatings can both effectively lower the temperature at different depths and delay the charring behavior of timber. The reduction in charring rates increased with the increase of coating quantity and decreased as the fire exposure time progressed. The ratio of delayed charring for two coatings can be over 30 % in the initial stage of fire and over 20 % for 1-h standard fire exposure. This study can provide technical support for enhancing the fire resistance of timber structures using transparent coatings.

Fire performance of CFRP-strengthened piloti-type columns with fire-resistant materials during standard fire exposure

This paper presents a numerical investigation into the fire endurance of carbon fiber reinforced polymer (CFRP)-strengthened columns, shielded with fire-resistant materials, in piloti-type reinforced concrete buildings. The strengthened column, equipped with a fire protection system, underwent exposure to the ASTM E119 standard time-temperature curve for a duration of 4 h. To comprehensively evaluate the thermal and structural performance of the strengthened column at elevated temperatures and substantiate the effectiveness of the fire protection system, a fully coupled thermal-stress analysis was conducted. The numerical modeling approach employed in this study was rigorously validated through previous experimental studies in conjunction with adherence to the ACI design guideline, specifically ACI 440.2R-17. Using the validated structural fire model, the thermal and structural behaviors of the RC column with an insulated CFRP strengthening system were investigated based on four key performance criteria: glass transition temperature, ignition temperature of polymer matrix, critical temperature of reinforcing bars, and the design axial load capacity at elevated temperatures. Furthermore, a comparative assessment of fire endurance was performed using diverse fire-resistant materials, including Sprayed Fire-Resistive Material (SFRM) and Sikacrete®-213 F, with insulation thicknesses ranging from 10 to 30 mm, during the 4-hour fire exposure period.

Thermal behavior of adhesively bonded timber‐concrete composite slabs subjected to standard fire exposure

AbstractFire tests were performed for the first time on adhesively bonded timber‐concrete composite slabs. The two medium‐scale (1.8 × 1.25 m) slabs were produced by gluing an 80‐mm thick three‐layer cross‐laminated timber (CLT) board to a 50 mm thick prefabricated reinforced concrete (RC) slab with epoxy and polyurethane (PUR) adhesives, respectively. The behavior of the composite slabs under elevated temperature was monitored by (1) observing the burning behavior of the used CLT, for example, charring and delamination and (2) measuring the temperature development at different locations of the CLT slabs, in the adhesive bond between concrete and timber boards, and in RC slabs. It was found that employing a one‐dimensional charring model for pure softwood, as prescribed by Eurocode 5‐1‐2, underestimated the charring depth of CLT due to the delamination effects. Measurements revealed that the average charring rates in the middle layer of CLT panels were approximately 0.65 mm/min, suggesting that the presence of concrete does not significantly affect the thermal behavior of the CLT panel. Delamination within the CLT was observed when its adhesive temperature was around 230°C. It was followed by the free‐fall of delaminated wood plies, which progressed slowly and lasted until the end of the test. At 90 min into the test, the temperatures of epoxy at the nine locations ranged between 55°C and 130°, while that of PUR between 60°C and 100°. The adhesive between concrete and CLT could lose stiffness significantly along the rising of temperature after surpassing of glass transition temperature (58°C for epoxy and 23°C for PUR in this study). The results indicated a high risk of weakening the composite action between the concrete slab and timber board. The measured temperatures of steel rebar were lower than 50°C. However, the concrete temperature reached about 120°C and the concrete cracked due to the distinct thermal expansions between concrete and timber and the rigid constraint of adhesive bond.

Effect of fiber types on fire-induced spalling and thermal performance of UHPC circular columns

Ultra-high-performance concrete (UHPC) emerged as a promising material for modern construction, offering unparalleled strength, durability, and versatility. However, there is limited research regarding UHPC's response to fire, prompting urgent investigation and analysis. This paper presents an experimental study focused on evaluating the effect of different types of fibers on the fire performance of UHPC circular columns. The fiber types considered in this study included steel fibers (SF), a hybrid mix of steel and polypropylene fibers (SPPF), and polyvinyl alcohol fibers (PVAF). Additionally, a control column was cast without the inclusion of any fibers. All UHPC specimens were subjected to standard fire exposure, following the ASTM E119 fire test. The results indicated a substantial resistance to spalling with the incorporation of fibers. Moreover, the column featuring PVAF exhibited the lowest internal temperature readings among the columns. Columns reinforced with SF and SPPF exhibited uniform spalling on all sides.

Fire behaviour of damaged wood–steel–wood beam connections retrofitted with self-tapping screws — experimental study

This experimental study aimed to investigate the structural fire behaviour of damaged glulam beam connections retrofitted using self-tapping screws (STS). Four full-size glulam beam-end bolted connections with wood–steel–wood connection configurations using four or six bolts arranged in two different bolt patterns were examined. All connections were retrofitted using STS after being deliberately damaged through physical testing until failure. In a subsequent stage, the retrofitted connections were experimentally tested under standard fire exposure while subjected to the maximum design load of the weakest, undamaged, unreinforced connection configuration. The influence of the application of STS in terms of preventing wood-splitting propagation and maintaining reasonable fire resistance for the retrofitted connections was experimentally investigated and proven in this study. Results show that the retrofitted glulam beam connections maintained a minimum of approximately 67% of the failure time of identical but undamaged, unreinforced connections under standard fire exposure.

THE STRUCTURAL BEHAVIOR OF RECYCLED AGGREGATE CONCRETE WALLS UNDER FIRE EXPOSURE: A FINITE ELEMENT ANALYSIS

Climate change is raising the demand for change in the construction industry, particularly in the concrete industry. One of the approaches to increase sustainability in the concrete industry is the use of recycled aggregate concrete (RAC). Many studies examined the type and composition of RAC used in construction applications. However, fewer studies examined the structural engineering applications of RAC. Thus, this study investigates the use of RAC in bearing walls. It presents a comprehensive thermal and structural performance assessment of RAC walls exposed to fire using finite element analysis (FEA). The FE model incorporates experimental material models in the literature that consider the degradation of the mechanical properties of RAC at high temperatures. The investigation encompasses a range of critical response measures, including the out-of-plane response of RAC walls under standard fire exposure and the overall stability of the walls during fire scenarios. The walls' out-of-plane and axial deflection and damage patterns were presented. The upper and lower bounds of performance were presented to examine the effect of material models’ variability on the response. The findings of this study reveal the complex interaction between fire scenarios, material properties, and their effect on the structural behavior of RAC walls. This study contributes to the growing knowledge on using RAC in structural engineering applications and promoting environmentally friendly materials in the construction industry while ensuring structural safety.

THE STRUCTURAL BEHAVIOR OF RECYCLED AGGREGATE CONCRETE WALLS UNDER FIRE EXPOSURE: A FINITE ELEMENT ANALYSIS

Climate change is raising the demand for change in the construction industry, particularly in the concrete industry. One of the approaches to increase sustainability in the concrete industry is the use of recycled aggregate concrete (RAC). Many studies examined the type and composition of RAC used in construction applications. However, fewer studies examined the structural engineering applications of RAC. Thus, this study investigates the use of RAC in bearing walls. It presents a comprehensive thermal and structural performance assessment of RAC walls exposed to fire using finite element analysis (FEA). The FE model incorporates experimental material models in the literature that consider the degradation of the mechanical properties of RAC at high temperatures. The investigation encompasses a range of critical response measures, including the out-of-plane response of RAC walls under standard fire exposure and the overall stability of the walls during fire scenarios. The walls' out-of-plane and axial deflection and damage patterns were presented. The upper and lower bounds of performance were presented to examine the effect of material models’ variability on the response. The findings of this study reveal the complex interaction between fire scenarios, material properties, and their effect on the structural behavior of RAC walls. This study contributes to the growing knowledge on using RAC in structural engineering applications and promoting environmentally friendly materials in the construction industry while ensuring structural safety.

Numerical analysis of fire-exposed reinforced concrete sections for assessing post-heating axial and flexural capacity

PurposeThis study investigates the impact of the fire decay phase on structural damage using the sectional analysis method. The primary objective of this work is to forecast the non-dimensional capacity parameters for the axial and flexural load-carrying capacity of reinforced concrete (RC) sections for heating and the subsequent post-heating phase (decay phase) of the fire.Design/methodology/approachThe sectional analysis method is used to determine the moment and axial capacities. The findings of sectional analysis and heat transfer for the heating stage are initially validated, and the analysis subsequently proceeds to determine the load capacity during the fire’s heating and decay phases by appropriately incorporating non-dimensional sectional and material parameters. The numerical analysis includes four fire curves with different cooling rates and steel percentages.FindingsThe study’s findings indicate that the rate at which the cooling process occurs after undergoing heating substantially impacts the axial and flexural capacity. The maximum degradation in axial and flexural capacity occurred in the range of 15–20% for cooling rates of 3 °C/min and 5 °C/min as compared to the capacity obtained at 120 min of heating for all steel percentages. As the fire cooling rate reduced to 1 °C/min, the highest deterioration in axial and flexural capacity reached 48–50% and 42–46%, respectively, in the post-heating stage.Research limitations/implicationsThe established non-dimensional parameters for axial and flexural capacity are limited to the analysed section in the study owing to the thermal profile, however, this can be modified depending on the section geometry and fire scenario.Practical implicationsThe study primarily focusses on the degradation of axial and flexural capacity at various time intervals during the entire fire exposure, including heating and cooling. The findings obtained showed that following the completion of the fire’s heating phase, the structural capacity continued to decrease over the subsequent post-heating period. It is recommended that structural members' fire resistance designs encompass both the heating and cooling phases of a fire. Since the capacity degradation varies with fire duration, the conventional method is inadequate to design the load capacity for appropriate fire safety. Therefore, it is essential to adopt a performance-based approach while designing structural elements' capacity for the desired fire resistance rating. The proposed technique of using non-dimensional parameters will effectively support predicting the load capacity for required fire resistance.Originality/valueThe fire-resistant requirements for reinforced concrete structures are generally established based on standard fire exposure conditions, which account for the fire growth phase. However, it is important to note that concrete structures can experience internal damage over time during the decay phase of fires, which can be quantitatively determined using the proposed non-dimensional parameter approach.

Experimental study and theoretical analysis of fire resistance properties of prestressed glued laminated timber beams

The addition of prestressing not only improves the force resistance of glulam beams, but also provides a potential solution to improve their fire resistance. An in-depth study of the fire behavior of prestressed glulam beams (PGBs) under fire and the force behavior after fire is essential for their fire resistance design and evaluation. In this paper, fire tests and post-fire four-point bending experiments were conducted on the PGBs aiming to investigate the thermal response of the PGBs as well as their force resistance after fire. The results showed that fire significantly affected the mechanical properties of the PGBs, not only reducing the prestressing force during the fire, but also decreasing the residual load carrying capacity after the fire. After 60 min of standard fire exposure, the prestress and load capacity of the PGBs decreased by 10 % and 33.33 %, respectively. Increasing either prestress or reinforcement ratio can effectively improve the resistance performance of the PGBs after fire. In the same fire action time, if the prestress was increased by 59.46 % or the reinforcement ratio was increased by 0.53 %, the residual ultimate load capacity of the PGBs was increased by 17.14 % and 22.19 %, respectively. The study also indicates that fully utilizing the synergistic effect of prestressing and reinforcement ratio enhancement can significantly improve the overall performance of the PGBs. In addition, a theoretical calculation model is proposed to accurately predict the residual flexural capacity of the PGBs after fire, which provides a theoretical support for the fire-resistant design of the PGBs before fire and the assessment of residual load capacity after fire.

Post-fire bond behaviour of reinforcement in concrete considering different bonded lengths and position of rebars

RC structures can be subjected to accidental fire load during their service life, which can have a strong negative effect on the bond strength. A reliable assessment of the bond behaviour after a fire event is essential to judge whether the fire affected structure is safe for further usage or does it require retrofitting or replacement. Until now, rather limited research has been carried out to understand the post-fire bond behaviour of reinforcement in concrete. This work reports and discusses the results of an experimental study on the post-fire (residual) bond behaviour carried out using beam-end-specimens, which simulate the boundary conditions closer to reality compared to conventional pull-out-specimens. The standard fire scenario is employed to expose the rebar to fire from one-side and three-sides for simulating the boundary conditions of a slab and a beam respectively. The specimens are subjected to fire for the target fire exposure duration and allowed to cool down naturally. An unconfined pull-out test is carried out thereafter to obtain the post-fire bond behaviour. The investigations reported here were carried out to study two aspects: (i) influence of concrete cover on the residual bond behaviour of the rebar placed at the corner of the specimen, and (ii) influence of bond length on the residual bond behaviour of rebar placed at the edge or in the corner. The test results highlighted the strong influence of fire on bond behaviour, with approx. 50% reduction in the bond capacity and even stronger reduction in bond stiffness just after 30 min of standard fire exposure. This is attributable partly to the material degradation and partly to the high thermal gradients and associated cracking.

Axial compression behaviour and design of square tubed steel reinforced-concrete stub columns after fire exposure

The tubed steel reinforced-concrete (TSRC) column is an innovative type of steel-concrete composite column, the steel tube of which mainly provides confinement to concrete core without sustaining axial load directly. This paper presents the axial compressive behaviour of square TSRC stub columns after ISO 834 standard fire exposure, experimentally and numerically. Eighteen square TSRC stub columns were heated and cooled and subsequently loaded to failure under axial compression. The influences of heating time, concrete compressive strength and steel tube area ratio on the load vs. displacement response, failure mode, residual capacity and stiffness of the tested columns were investigated. Finite element analysis (FEA) models were then developed and validated against test results. The working mechanism, e.g. confinement effect and axial force distribution within the composite section, was studied via parametric studies. Both the residual ultimate capacity and axial stiffness of square TSRC stub columns decrease significantly with the increase in heating time. The negative effect of fire exposure on residual stiffness is more significant than on the residual capacity. Finally, practical equations for determining the residual ultimate capacity and residual compressive stiffness of square TSRC stub column were proposed, which remain consistent with the ambient-temperature methods given in current design standard.

Experimental and numerical investigation of reduced web section connections in fire

AbstractThis paper presents the details and analysis of a fire test conducted on a reduced web section (RWS) connection for steel framed construction. The test was completed in the fire laboratory at Tampere University in order to assess how these connections, usually selected and designed for their seismic performance, behave under fire conditions. RWS connections were first devised for fixed joints in steel framed buildings, with a view to moving the plastic hinge away from the column face during an extreme event such as an earthquake, thus improving the ductility of the structure. Until now, there was very little known of their behaviour under fire conditions. Accordingly, the current paper provides a detailed description and analysis of the fire test on a RWS connection, during which the arrangement lasted for around 16 minutes of standard fire exposure. It also describes the development of a numerical model, which is validated against the test data. The purpose of the model is to enable a more thorough examination of the various parameters and variables that may exist in a real structure, subjected to a real fire.

Thickness of zero-strength layer in timber beam exposed to fuel-controlled parametric fires

Fire resistance is one of the essential requirements to be fulfilled in the design of timber structures. For this purpose, a reduced cross-section method is given in the European standards, Eurocodes. The method is based on the assumption that an initial, rectangular timber cross-section exposed to fire conditions reduces to an effective cross-section, which has material properties as at a room temperature. The reduced part of the cross-section with no resistance is determined by a sum of two parameters, namely a charring depth and a thickness of zero-strength layer. Eurocodes give a value of the latter only for the standard fire exposure, which is only one of the fire curves proposed in the same standards. Therefore, the present paper examines the thickness of zero-strength layer in case of 46 different fuel-controlled parametric fire exposures applied to a timber beam from three sides. A four-phase numerical analysis is applied for this purpose that includes the use of a hygro-thermal model and a mechanical model to determine temperatures of timber over the cross-section and the mechanical resistance of timber beam in fire conditions, respectively. The results show that the thickness of zero-strength layer takes the values between 7.9 and 18.4 mm for the fuel-controlled parametric fire exposures. Since it is clearly dependent on the parameters describing the parametric fire curve, five equations are proposed that can be used for determination of the thickness of zero-strength layer in case of parametric fire exposures.

Case studies on determining fire resistance of uniaxial bending reinforced concrete columns subjected to 4-side standard fire exposure

This article introduces technical specifications and calculation instructions for fire resistance of uniaxial bending rectangular reinforced concrete (RC) columns under 4-side heating by standard fire. Although a number ofresearch works have been conducted following the Eurocodes to meet the long-term requirement of the country’s development in construction, it is shown that the Russian design standard SP 468.1325800.2019 (SP 468) is also applicable for concrete structures subjected to fire in the Vietnam current context. Tabulated data and simplified calculation methods according to SP 468 are introduced, followed by two practical case studies for demonstration. The calculation results show that by using the simplified calculation method the RC columns’fire-resistant limit can be explicitly determined with a particular safety factor ku, T, and a more economical design solution can be obtained compared to that of the tabulated data method. Additionally, RC columns loaded with small eccentricities exhibit greater fire resistance advantages compared to those with large-eccentricity loading. A number of other useful observations are also discussed in the latter part of this article.

The Behavior of Passive Fire Protection Materials Used for Fire Protection of Steel Structures in Standard, Hydrocarbon, and Jet Fire Exposure

Structural steel, when exposed to fire, loses its tensile strength and ability to resist deformation. Both organic and inorganic material-based passive fire protection systems, are being traditionally used to protect steel structures in such scenarios. This study focused on comparing the performance of the same organic and inorganic coatings in standard fire, hydrocarbon fire, and jet fire conditions. Standard, hydrocarbon fire, and jet fire experiments were carried out in full-scale fire resistance furnaces as per ASTM E-119, UL 1709, and ISO 22899-1 respectively. From the results, it was observed that both organic and inorganic materials tend to underperform in jet fire scenarios, when compared with standard and hydrocarbon fire due to the impingement/turbulence effect and the thermo-mechanical effect caused by the velocity of the gas.

Modelling charring of timber exposed to natural fire

Charring of timber structural elements in fire is one of the most fundamental phenomena that affect the fire resistance of these elements. For an accurate and safe design of structural fire resistance, it is important to consider charring of timber in natural fire exposures, since determining charring for standard fire exposure, which is a common practice, is outdated and in some cases unsafe, due to the fact that some natural fires can be much more severe. Currently, the prescriptive approach and simplified design methods fail to give information about charring of timber elements exposed to natural fire and thus, a performance-based design is needed. Therefore, this paper presents an upgrade and extension of a recently developed heat-mass-pyrolysis model named PYCIF. Originally, PYCIF model was developed only for standard fire conditions. In the present paper, several studies and analyses are performed to extend model application to natural fire conditions. Firstly, the sensitivity study is performed, where the impact of model parameters on the charring development is investigated. It is discovered, that the kinetic parameters for the reaction rate of the active cellulose production, namely activation energy E1 and pre-exponential factor A1, are the most influential. In the next analyses the model calibration for small-scale cone calorimeter tests and large-scale natural fire tests of cross-laminated timber (CLT) floor system is performed. A robust nature of the model is identified since minor parameter calibration is required for an accurate prediction of the charring depth and temperatures in timber elements exposed to various fire conditions. Furthermore, a strong connection between the heating rate of fire and kinetic parameters is discovered. In cases of faster heating rate, the kinetic parameters govern slower reaction rate of active cellulose.

Evaluation of the thermo-physical, mechanical, and fire resistance performances of limestone calcined clay cement (LC3)-based lightweight rendering mortars

Limestone-calcined clay cement (LC3) is one of the potential green or low-carbon binders for replacing ordinary Portland cement (OPC), leading to sustainable infrastructure development. Improving the thermal properties of the building's rendering mortar is an effective solution to reduce the building's energy consumption. In this study, LC3 has been prepared by replacing 60 wt% of OPC with a blend of limestone (LS) powder and metakaolin (MK) with LS: MK of 1:2 (wt%). Three mixtures of LC3-based lightweight mortars were prepared in which the binder was combined with three types of expanded/exfoliated insulant lightweight aggregates (LWAs), including expanded perlite (EP), expanded clay (EC), and exfoliated vermiculite (EVM), with aggregate volume contents of 75%. Compressive strength, in-direct tensile strength, bulk density, thermal conductivity, thermal diffusivity, specific heat, volume of permeable voids, and capillary water absorption, have been assessed. The effect of fire on the compressive strength and microstructure has been studied to explore the thermal stability of the prepared mortars. The newly developed LC3-mortars possessed densities below the specified limit for lightweight rendering mortars (i.e., ≤1300 kg/m3) accompanied with good thermal insulation performance. The mortar incorporating EP showed the lowest thermal conductivity (≈0.2 W/m.K), the highest thermal mass (≈2.3 MJ/m3. K) and the lowest compressive strength (≈6.76 MPa). The EVM mortar showed the highest strength retention efficiency; a residual strength of about 79.4% was obtained after standard fire exposure for an hour. The integration of LWAs into the LC3 binder matrix is helpful in improving the structural integrity upon fire exposure. The simultaneous improvement of thermal and mechanical properties in addition to fire resistance with the potential to reduce carbon footprint summarize the major innovation presented in this study.

Performance assessment of limestone calcined clay cement (LC3)-Based lightweight green mortars incorporating recycled waste aggregate

Limestone-calcined clay cement (LC3) is one of the green or low-carbon binder options for replacing Portland cement, leading to sustainable construction. Reducing the thermal conductivity of the building's rendering mortar is helpful in reducing energy consumption for heating and cooling in buildings. In this study, LC3 has been prepared by replacing 60 wt% of White Portland Cement (WPC) with a blend of limestone (LS) powder and metakaolin (MK) with LS: MK of 1:2 (wt%). Lightweight LC3-based mortars were prepared in which the binder was combined with recycled fine aggregate (RFA) from autoclaved aerated concrete waste (AACW) with aggregate volume contents of 25, 50, and 75%. Mechanical, thermal, and hygric parameters, including compressive strength, in-direct tensile strength, bulk density, thermal conductivity, volume of permeable voids (VPV), and capillary water absorption, have been investigated after 28 days of curing. In order to explore the thermal stability of the prepared mortars, the residual strength after exposure to standard fire has been examined. The LC3-mortar incorporating 75 vol% of AACW possessed a bulk density of 1230 kg/m3; i.e., below the specified limit for lightweight rendering mortars. In addition, a reduced thermal conductivity (as low as 0.21 W/m K) has been obtained. Even at the highest volume content of AACW in the LC3-binder matrix, the lowest compressive strength was significant (13 MPa). Moreover, the newly developed mortars showed enhanced strength retention efficiency; a residual strength of about 61.5% was achieved after standard fire exposure for an hour (1hr). SEM analysis exhibited adequate bonding and a dense interface between the AACW aggregate and the LC3-binder matrix.

Assessment of fire exposure on the load bearing capacity of basement storey walls

This paper presents the numerical modelling of the fire exposure on structural element and its static analysis taking account of the material properties reduction due to elevated temperature.
 The reinforced concrete wall of basement storey was subjected to one side fire exposure.
 Advanced calculation methods were used to assess the fire exposure on the structural element as most reliable and approximate to fire test results. Thermal analysis was performed with LIRA-CAD software by the simulating of three main heat-transfer ways: thermal conductivity, convection and radiation. As a result of the thermal analysis, temperature distribution in the concrete and reinforcement parts of the structural element cross-section was obtained. The thermal analysis of the wall structural element was performed for 120 minutes in standard fire exposure. Reduction factors for the strength of concrete and reinforcement steel were determined based on the temperature distribution in the wall structural element cross-section. The cross-section is divided into a number of parallel zones of equal thickness where the mean temperature and the corresponding mean compressive strength is assessed according to the Zone method procedure. The fire damaged zone of thickness az at the fire exposed sides and reduced cross-section were obtained.
 Static analysis of the wall load-bearing capa-city was performed using the procedure applicable for normal temperature design. The Deformation method for normal temperature design taking to account concrete deformation was used. The Deformation method for normal design taken to account concrete deformation at every step of iteration was used. The reduced load-bearing capacity of the fire damaged wall taking into account residual concrete strength was calculated and relevant load-bearing capacity diagrams were determined.