Pub Date : 2022-07-15DOI: 10.1108/jsfe-04-2022-0019
T. Coelho, S. Diniz, F. Rodrigues, Ruben Van Coile
PurposeThis paper aims to investigate the state of the art for the reliability evaluation of reinforced concrete beams in a fire situation. Special emphasis is placed on addressing which parameters were considered probabilistically or deterministically, the prescribed probabilistic models for the assumed stochastic variables, the treatment of the heat transfer mechanism, the quantification of the structural fire performance and the assumed target reliability levels.Design/methodology/approachResearch papers were identified through a search on the Web of Science, Google Scholar and detailed searches within the journals Journal of Structural Fire Engineering, Fire Technology and Fire Safety Journal, supplemented with references known by the authors.FindingsConsidering the state-of-the-art review, gaps in the literature are identified related to (1) the probabilistic evaluation of shear capacity for standard fires and parametric fires, and bending capacity for parametric fires, (2) the absence of reference fragility curves for immediate design application/code calibration and (3) the specification of target safety levels for reliability-based design.Originality/valueThe lack of research papers gathering studies on the reliability of reinforced concrete beams in fire situation makes it difficult to further develop research in the area. The value of this work lies precisely in the collection of the basic information, making it possible to identify gaps to be addressed in future research and the suggestion of a research framework.
{"title":"State-of-the-art review of the reliability evaluation of concrete beams exposed to fire","authors":"T. Coelho, S. Diniz, F. Rodrigues, Ruben Van Coile","doi":"10.1108/jsfe-04-2022-0019","DOIUrl":"https://doi.org/10.1108/jsfe-04-2022-0019","url":null,"abstract":"PurposeThis paper aims to investigate the state of the art for the reliability evaluation of reinforced concrete beams in a fire situation. Special emphasis is placed on addressing which parameters were considered probabilistically or deterministically, the prescribed probabilistic models for the assumed stochastic variables, the treatment of the heat transfer mechanism, the quantification of the structural fire performance and the assumed target reliability levels.Design/methodology/approachResearch papers were identified through a search on the Web of Science, Google Scholar and detailed searches within the journals Journal of Structural Fire Engineering, Fire Technology and Fire Safety Journal, supplemented with references known by the authors.FindingsConsidering the state-of-the-art review, gaps in the literature are identified related to (1) the probabilistic evaluation of shear capacity for standard fires and parametric fires, and bending capacity for parametric fires, (2) the absence of reference fragility curves for immediate design application/code calibration and (3) the specification of target safety levels for reliability-based design.Originality/valueThe lack of research papers gathering studies on the reliability of reinforced concrete beams in fire situation makes it difficult to further develop research in the area. The value of this work lies precisely in the collection of the basic information, making it possible to identify gaps to be addressed in future research and the suggestion of a research framework.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41327116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-11DOI: 10.1108/jsfe-02-2022-0006
Xiaomin Zhao, F. Ozaki, T. Hirashima, K. Kimura, Y. Murakami, Jun-ichi Suzuki, N. Yotsumoto
PurposeThe main purpose of this study was to propose theoretical calculation models to evaluate the theoretical bending strengths of welded wide-flange section steel beams with local buckling at elevated temperatures.Design/methodology/approachSteady-state tests using various test parameters, including width-thickness ratios (Class 2–4) and specimen temperatures (ambient temperature, 400, 500, 600, 700, and 800°C), were performed on 18 steel beam specimens using roller supports to examine the maximum bending moment and bending strength after local buckling. A detailed calculation model (DCM) based on the equilibrium of the axial force in the cross-section and a simple calculation model (SCM) for a practical fire-resistant design were proposed. The validity of the calculation models was verified using the bending test results.FindingsThe strain concentration at the local buckling cross-section was mitigated in the elevated-temperature region, resulting in a small bending moment degradation after local buckling. The theoretical bending strengths after local buckling, evaluated from the calculation models, were in good agreement with the test results at elevated temperatures.Originality/valueThe effect of local buckling on the bending behaviour after the maximum bending strength in high-temperature regions was quantified. Two types of calculation models were proposed to evaluate the theoretical bending strength after local buckling.
{"title":"Bending-strength evaluation of wide-flange steel beams subjected to local buckling at elevated temperatures","authors":"Xiaomin Zhao, F. Ozaki, T. Hirashima, K. Kimura, Y. Murakami, Jun-ichi Suzuki, N. Yotsumoto","doi":"10.1108/jsfe-02-2022-0006","DOIUrl":"https://doi.org/10.1108/jsfe-02-2022-0006","url":null,"abstract":"PurposeThe main purpose of this study was to propose theoretical calculation models to evaluate the theoretical bending strengths of welded wide-flange section steel beams with local buckling at elevated temperatures.Design/methodology/approachSteady-state tests using various test parameters, including width-thickness ratios (Class 2–4) and specimen temperatures (ambient temperature, 400, 500, 600, 700, and 800°C), were performed on 18 steel beam specimens using roller supports to examine the maximum bending moment and bending strength after local buckling. A detailed calculation model (DCM) based on the equilibrium of the axial force in the cross-section and a simple calculation model (SCM) for a practical fire-resistant design were proposed. The validity of the calculation models was verified using the bending test results.FindingsThe strain concentration at the local buckling cross-section was mitigated in the elevated-temperature region, resulting in a small bending moment degradation after local buckling. The theoretical bending strengths after local buckling, evaluated from the calculation models, were in good agreement with the test results at elevated temperatures.Originality/valueThe effect of local buckling on the bending behaviour after the maximum bending strength in high-temperature regions was quantified. Two types of calculation models were proposed to evaluate the theoretical bending strength after local buckling.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49074276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-15DOI: 10.1108/jsfe-02-2022-0009
M. Shaheen, L. Cunningham, Andrew S. J. Foster
PurposeThe effect of bolt stripping failure on the ductility of steel end plate beam-column connections has received relatively little investigation to date. The objective with the present work is to establish a validated numerical model of end plate connections at elevated temperatures, which predicts the mechanical behaviour and failure modes observed in the experimental tests including the bolt stripping failure. Furthermore, the validated FE model was used to investigate the effect of stripping failure on both the rotational and load-bearing capacity of end plate connection.Design/methodology/approachThe analysis was conducted on a validated numerical model of end plate connections at elevated temperatures, which predicts the mechanical behaviour and failure modes observed in the experimental tests including the bolt stripping failure. The material was modelled considering ductile damage initiation and evolution featured in ABAQUS/Standard.FindingsThis study demonstrates that thick end plates can prevent stripping failure which significantly improves the rotational capacity of the connection. This failure mode can develop readily with thin end plates; however the effect is often unrealistically mitigated through idealised experimental tests. The rotational capacity of a connection can be 5.0 times higher if stripping failure is avoided, particularly at elevated temperatures. Eurocode 3 part 1.8 does not consider the possibility of stripping failure when discussing the requirements for plastic analysis. It is concluded in the present study that by allowing for the possibility of bolt stripping, the mode of failure can often shift from end plate failure to bolt stripping, this in turn significantly reduces the connection rotational capacity.Originality/valueThe effect of bolt stripping failure on the ductility of steel end plate beam-column connections has received relatively little investigation to date.
{"title":"Bolt stripping failure and ductility of end plate beam-column connections at ambient and elevated temperatures","authors":"M. Shaheen, L. Cunningham, Andrew S. J. Foster","doi":"10.1108/jsfe-02-2022-0009","DOIUrl":"https://doi.org/10.1108/jsfe-02-2022-0009","url":null,"abstract":"PurposeThe effect of bolt stripping failure on the ductility of steel end plate beam-column connections has received relatively little investigation to date. The objective with the present work is to establish a validated numerical model of end plate connections at elevated temperatures, which predicts the mechanical behaviour and failure modes observed in the experimental tests including the bolt stripping failure. Furthermore, the validated FE model was used to investigate the effect of stripping failure on both the rotational and load-bearing capacity of end plate connection.Design/methodology/approachThe analysis was conducted on a validated numerical model of end plate connections at elevated temperatures, which predicts the mechanical behaviour and failure modes observed in the experimental tests including the bolt stripping failure. The material was modelled considering ductile damage initiation and evolution featured in ABAQUS/Standard.FindingsThis study demonstrates that thick end plates can prevent stripping failure which significantly improves the rotational capacity of the connection. This failure mode can develop readily with thin end plates; however the effect is often unrealistically mitigated through idealised experimental tests. The rotational capacity of a connection can be 5.0 times higher if stripping failure is avoided, particularly at elevated temperatures. Eurocode 3 part 1.8 does not consider the possibility of stripping failure when discussing the requirements for plastic analysis. It is concluded in the present study that by allowing for the possibility of bolt stripping, the mode of failure can often shift from end plate failure to bolt stripping, this in turn significantly reduces the connection rotational capacity.Originality/valueThe effect of bolt stripping failure on the ductility of steel end plate beam-column connections has received relatively little investigation to date.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46717693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-13DOI: 10.1108/jsfe-02-2022-0005
T. Pinger, Martin Mensinger, Maria Firan
PurposeBased on the advantages of conventional hot-dip galvanizing made from quasi-pure zinc melts in the event of fire, this article aims to perform a series of tests to verify whether a similar effect can be achieved with zinc-aluminum coatings.Design/methodology/approachThe emissivity of galvanized surfaces, which were applied to steel specimens by the batch hot-dip galvanizing process, was experimentally determined under continuously increasing temperature load. In addition to a quasi-pure zinc melt serving as a reference, a zinc melt alloyed with 500 ppm aluminum and thin-film galvanized with a melt of zinc and 5% aluminum were used. For the latter, variants of post-treatment measures in terms of a passivation and sealing of the galvanizing were also investigated.FindingsThe results show that lower emissivity can be achieved at higher temperatures by adding aluminum to the zinc melt and thereby into the zinc coating. The design values required for the structural fire design were proposed, and an exemplary calculation of the temperature development in the case of fire was carried out based on the values. The result of this calculation indicates that the savings potential becomes apparent, when using zinc-aluminum coatings.Originality/valueThe presented novel tests describe the behavior of zinc-aluminum coatings under the influence of elevated temperatures and their positive effect on the emissivity of steel components galvanized by this method. The results provide valuable insights and information on the performance in the event of fire and the associated potential savings for steel construction.
{"title":"Behavior of hot-dip zinc-aluminum coated steel under elevated temperature in case of fire","authors":"T. Pinger, Martin Mensinger, Maria Firan","doi":"10.1108/jsfe-02-2022-0005","DOIUrl":"https://doi.org/10.1108/jsfe-02-2022-0005","url":null,"abstract":"PurposeBased on the advantages of conventional hot-dip galvanizing made from quasi-pure zinc melts in the event of fire, this article aims to perform a series of tests to verify whether a similar effect can be achieved with zinc-aluminum coatings.Design/methodology/approachThe emissivity of galvanized surfaces, which were applied to steel specimens by the batch hot-dip galvanizing process, was experimentally determined under continuously increasing temperature load. In addition to a quasi-pure zinc melt serving as a reference, a zinc melt alloyed with 500 ppm aluminum and thin-film galvanized with a melt of zinc and 5% aluminum were used. For the latter, variants of post-treatment measures in terms of a passivation and sealing of the galvanizing were also investigated.FindingsThe results show that lower emissivity can be achieved at higher temperatures by adding aluminum to the zinc melt and thereby into the zinc coating. The design values required for the structural fire design were proposed, and an exemplary calculation of the temperature development in the case of fire was carried out based on the values. The result of this calculation indicates that the savings potential becomes apparent, when using zinc-aluminum coatings.Originality/valueThe presented novel tests describe the behavior of zinc-aluminum coatings under the influence of elevated temperatures and their positive effect on the emissivity of steel components galvanized by this method. The results provide valuable insights and information on the performance in the event of fire and the associated potential savings for steel construction.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41970822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-08DOI: 10.1108/jsfe-01-2022-0001
F. Ozaki, T. Umemura
PurposeIn this study, engineering stress-strain relationships considering an effect of strain rate on steel materials at elevated temperatures were formulated and a simplified analytical model using a two-dimensional beam element to analytically examine the effect of strain rate on the load-bearing capacity and collapse temperature was proposed.Design/methodology/approachThe stress-strain relationships taking into account temperature, strain, and strain rate were established based on the past coupon test results with strain rate as the test parameter. Furthermore, an elasto-plastic analysis using a two-dimensional beam element, which considered the effect on strain rate, was conducted for both transient- and steady-state conditions.FindingsThe analytical results agreed relatively well with the test results, which used small steel beam specimens with a rectangular cross-section under various heating rates (transient-state condition) and deformation rates (steady-state condition). It was found that the bending strength and collapse temperature obtained from the parametric analyses agreed relatively well with those evaluated using the effective strength obtained from the coupon tests with strain equal to 0.01 or 0.02 under the fast strain rates.Originality/valueThe effect of stress degradation, including the stress-strain relationships at elevated temperature, was mitigated by considering the effect of strain rate on the analytical model. This is an important point to consider when considering the effect of strain rate on steel structural analysis at elevated temperatures to maintain analytical stability unaccompanied by the stress degradation.
{"title":"Proposal of steel stress-strain relationships and simple analytical models of beams considering strain-rate effects at elevated temperatures","authors":"F. Ozaki, T. Umemura","doi":"10.1108/jsfe-01-2022-0001","DOIUrl":"https://doi.org/10.1108/jsfe-01-2022-0001","url":null,"abstract":"PurposeIn this study, engineering stress-strain relationships considering an effect of strain rate on steel materials at elevated temperatures were formulated and a simplified analytical model using a two-dimensional beam element to analytically examine the effect of strain rate on the load-bearing capacity and collapse temperature was proposed.Design/methodology/approachThe stress-strain relationships taking into account temperature, strain, and strain rate were established based on the past coupon test results with strain rate as the test parameter. Furthermore, an elasto-plastic analysis using a two-dimensional beam element, which considered the effect on strain rate, was conducted for both transient- and steady-state conditions.FindingsThe analytical results agreed relatively well with the test results, which used small steel beam specimens with a rectangular cross-section under various heating rates (transient-state condition) and deformation rates (steady-state condition). It was found that the bending strength and collapse temperature obtained from the parametric analyses agreed relatively well with those evaluated using the effective strength obtained from the coupon tests with strain equal to 0.01 or 0.02 under the fast strain rates.Originality/valueThe effect of stress degradation, including the stress-strain relationships at elevated temperature, was mitigated by considering the effect of strain rate on the analytical model. This is an important point to consider when considering the effect of strain rate on steel structural analysis at elevated temperatures to maintain analytical stability unaccompanied by the stress degradation.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46344211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-07DOI: 10.1108/jsfe-01-2022-0004
Naser Alimrani, G. Balázs, Nabil Abdelmelek
Purpose This study aims to test push-off specimens at elevated temperatures. This research work is part of the author’s PhD work. The author has published several of the significant findings that were remarkably cited in short time. This research is a continuation of that work, yet it has new findings as well. The author hopes this to be accepted and published.Design/methodology/approachThe approach that was used herein is widely used in the field i.e., the push-off specimen testing. The author has used this approach to investigate the shear performance of concrete exposed to elevated temperatures. In addition, the author has used means of Linear Variable Differential Transformers (LVDTs) to record the displacements of the loading.FindingsResults showed that, at ambient temperature, shear capacity is significantly increased by the virtue of using cocktail fibres, while insignificant increase is noticed using polymeric fibres only. However, significant decrease is noticed when elevated temperatures are included for both mixes.Originality/valueMany of the research findings here were accepted as New Scientific Results in my PhD Thesis. The novelty is remarkable and was appreciated by the committee.
{"title":"One-year push-off specimens using cocktail and polymeric fibres at elevated temperatures","authors":"Naser Alimrani, G. Balázs, Nabil Abdelmelek","doi":"10.1108/jsfe-01-2022-0004","DOIUrl":"https://doi.org/10.1108/jsfe-01-2022-0004","url":null,"abstract":"Purpose This study aims to test push-off specimens at elevated temperatures. This research work is part of the author’s PhD work. The author has published several of the significant findings that were remarkably cited in short time. This research is a continuation of that work, yet it has new findings as well. The author hopes this to be accepted and published.Design/methodology/approachThe approach that was used herein is widely used in the field i.e., the push-off specimen testing. The author has used this approach to investigate the shear performance of concrete exposed to elevated temperatures. In addition, the author has used means of Linear Variable Differential Transformers (LVDTs) to record the displacements of the loading.FindingsResults showed that, at ambient temperature, shear capacity is significantly increased by the virtue of using cocktail fibres, while insignificant increase is noticed using polymeric fibres only. However, significant decrease is noticed when elevated temperatures are included for both mixes.Originality/valueMany of the research findings here were accepted as New Scientific Results in my PhD Thesis. The novelty is remarkable and was appreciated by the committee.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46599206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-31DOI: 10.1108/jsfe-08-2021-0050
S. V. Khonsari, Shahin Nejati, Mohammadreza Rahdan, Mehdi Ahmadi
PurposeThe paper aims to report a fire test conducted on a three-dimensional frame in order to investigate the behaviour of bare steel flush end-plate connections with relatively low thickness at elevated temperatures.Design/methodology/approachA half-scale model was fabricated and exposed to modified (scaled) ISO 834 heating curve using a semi-open furnace. The maximum temperature inside the furnace reached 1,026 °C.FindingsThe rotations of connections are reported and compared with those of a previous study on an exactly the same model with thick end-plates. Various modes of failure such as local buckling of the beams flanges and lateral-torsional buckling of beams were observed during the test. Finally, the structure collapsed after 29 min of heating due to the fracture of weld between one of the beams and one of its attached end-plates whilst the other beam had undergone a maximum deflection of 35 cm (≈ 1/6 span length). Other observed failure modes included bolt fracture, bolt thread stripping and large inelastic deformation of the end-plates.Originality/valueAlthough the adoption of thin end-plates increased the rotational capacity of the connections, it did not improve the robustness of the structure under fire conditions.
{"title":"Behaviour of thin flush end-plate connections in a 3D bare steel frame under fire loading: experimental study","authors":"S. V. Khonsari, Shahin Nejati, Mohammadreza Rahdan, Mehdi Ahmadi","doi":"10.1108/jsfe-08-2021-0050","DOIUrl":"https://doi.org/10.1108/jsfe-08-2021-0050","url":null,"abstract":"PurposeThe paper aims to report a fire test conducted on a three-dimensional frame in order to investigate the behaviour of bare steel flush end-plate connections with relatively low thickness at elevated temperatures.Design/methodology/approachA half-scale model was fabricated and exposed to modified (scaled) ISO 834 heating curve using a semi-open furnace. The maximum temperature inside the furnace reached 1,026 °C.FindingsThe rotations of connections are reported and compared with those of a previous study on an exactly the same model with thick end-plates. Various modes of failure such as local buckling of the beams flanges and lateral-torsional buckling of beams were observed during the test. Finally, the structure collapsed after 29 min of heating due to the fracture of weld between one of the beams and one of its attached end-plates whilst the other beam had undergone a maximum deflection of 35 cm (≈ 1/6 span length). Other observed failure modes included bolt fracture, bolt thread stripping and large inelastic deformation of the end-plates.Originality/valueAlthough the adoption of thin end-plates increased the rotational capacity of the connections, it did not improve the robustness of the structure under fire conditions.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43133782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-21DOI: 10.1108/jsfe-10-2021-0065
Jason Martinez, A. Jeffers
PurposeA methodology for producing an elevated-temperature tension stiffening model is presented.Design/methodology/approachThe energy-based stress–strain model of plain concrete developed by Bažant and Oh (1983) was extended to the elevated-temperature domain by developing an analytical formulation for the temperature-dependence of the fracture energy Gf. Then, an elevated-temperature tension stiffening model was developed based on the modification of the proposed elevated-temperature tension softening model.FindingsThe proposed tension stiffening model can be used to predict the response of composite floor slabs exposed to fire with great accuracy, provided that the global parameters TS and Kres are adequately calibrated against global structural response data.Originality/valueIn a finite element analysis of reinforced concrete, a tension stiffening model is required as input for concrete to account for actions such as bond slip and tension stiffening. However, an elevated-temperature tension stiffening model does not exist in the research literature. An approach for developing an elevated-temperature tension stiffening model is presented.
{"title":"Tension stiffening model for the finite element analysis of composite floor systems exposed to fire","authors":"Jason Martinez, A. Jeffers","doi":"10.1108/jsfe-10-2021-0065","DOIUrl":"https://doi.org/10.1108/jsfe-10-2021-0065","url":null,"abstract":"PurposeA methodology for producing an elevated-temperature tension stiffening model is presented.Design/methodology/approachThe energy-based stress–strain model of plain concrete developed by Bažant and Oh (1983) was extended to the elevated-temperature domain by developing an analytical formulation for the temperature-dependence of the fracture energy Gf. Then, an elevated-temperature tension stiffening model was developed based on the modification of the proposed elevated-temperature tension softening model.FindingsThe proposed tension stiffening model can be used to predict the response of composite floor slabs exposed to fire with great accuracy, provided that the global parameters TS and Kres are adequately calibrated against global structural response data.Originality/valueIn a finite element analysis of reinforced concrete, a tension stiffening model is required as input for concrete to account for actions such as bond slip and tension stiffening. However, an elevated-temperature tension stiffening model does not exist in the research literature. An approach for developing an elevated-temperature tension stiffening model is presented.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43122781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-14DOI: 10.1108/jsfe-05-2021-0021
Virendra Kumar, R. Paswan
PurposeThis paper attempted to study the alkali-activated (AA) binder consisting of 94% of ground granulated blast furnace slag (GGBFS) and 6% of blended powder of alkali metal hydroxide and metal sulfate, which acted as an activator.Design/methodology/approachSeveral concrete specimens (cubes, cylinders and prisms), which were casted using AA binders, were further tested for mechanical properties after exposure to elevated temperatures of 200 °C, 400 °C, 600 °C and 800 °C. Additionally, to understand the structural behavior in uniaxial compressive load, reinforced concrete short columns were cast, cured and tested at ambient temperature as well as after exposure to 300 °C, 600 °C and 900 °C, to know the residual strength after exposure to elevated temperature.FindingsThe findings for the residual strength of alkali-activated slag binder concrete (AASBC) indicated a substantial agreement with the results obtained for the residual strength of Portland slag cement (PSC) concrete, thereby showing the effectiveness of binder when used as a replacement of cement.Originality/valueThe study clearly indicates that the binder developed is an effective approach for the 100% replacement of cement in the concrete.
{"title":"Residual properties of alkali-activated slag concrete exposed to elevated temperatures","authors":"Virendra Kumar, R. Paswan","doi":"10.1108/jsfe-05-2021-0021","DOIUrl":"https://doi.org/10.1108/jsfe-05-2021-0021","url":null,"abstract":"PurposeThis paper attempted to study the alkali-activated (AA) binder consisting of 94% of ground granulated blast furnace slag (GGBFS) and 6% of blended powder of alkali metal hydroxide and metal sulfate, which acted as an activator.Design/methodology/approachSeveral concrete specimens (cubes, cylinders and prisms), which were casted using AA binders, were further tested for mechanical properties after exposure to elevated temperatures of 200 °C, 400 °C, 600 °C and 800 °C. Additionally, to understand the structural behavior in uniaxial compressive load, reinforced concrete short columns were cast, cured and tested at ambient temperature as well as after exposure to 300 °C, 600 °C and 900 °C, to know the residual strength after exposure to elevated temperature.FindingsThe findings for the residual strength of alkali-activated slag binder concrete (AASBC) indicated a substantial agreement with the results obtained for the residual strength of Portland slag cement (PSC) concrete, thereby showing the effectiveness of binder when used as a replacement of cement.Originality/valueThe study clearly indicates that the binder developed is an effective approach for the 100% replacement of cement in the concrete.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47691624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01DOI: 10.1108/jsfe-03-2021-0012
Khadejah Alameen Abouleiwun, H. Elbakry, Muhammad Ahmed Diab, S. El-Fitiany
PurposeIn this study, the behavior of a multi-story flat plate structure during fire exposure is investigated using numerical simulations conducted with using ABAQUS software.Design/methodology/approachA three-dimensional finite element model is then carried out on the RC flat slab structure exposed to standard ISO-834 fire at different location arrangements. The model examines mid-span deflection, shear demand on the columns, bending moment and the membrane action of the floor slab.FindingsThe latter plays a main role to increase the capability and ductility of the slab at longer fire exposure to compensate the reduction in the flexural capacity. Also, shear demand in columns becomes bigger in cases of more than one surrounding slab exposed to fire at the same time.Originality/valueThis work focuses on the influence of the horizontal force on columns due to thermal expansion of slab which should be taken into account in the design of multistory multi-bay building considering it the same as the resulted horizontal force from the wind and seismic effect, the traveling fire and the restraint effect.
{"title":"Behavior of RC flat plate structure subjected to compartment fires","authors":"Khadejah Alameen Abouleiwun, H. Elbakry, Muhammad Ahmed Diab, S. El-Fitiany","doi":"10.1108/jsfe-03-2021-0012","DOIUrl":"https://doi.org/10.1108/jsfe-03-2021-0012","url":null,"abstract":"PurposeIn this study, the behavior of a multi-story flat plate structure during fire exposure is investigated using numerical simulations conducted with using ABAQUS software.Design/methodology/approachA three-dimensional finite element model is then carried out on the RC flat slab structure exposed to standard ISO-834 fire at different location arrangements. The model examines mid-span deflection, shear demand on the columns, bending moment and the membrane action of the floor slab.FindingsThe latter plays a main role to increase the capability and ductility of the slab at longer fire exposure to compensate the reduction in the flexural capacity. Also, shear demand in columns becomes bigger in cases of more than one surrounding slab exposed to fire at the same time.Originality/valueThis work focuses on the influence of the horizontal force on columns due to thermal expansion of slab which should be taken into account in the design of multistory multi-bay building considering it the same as the resulted horizontal force from the wind and seismic effect, the traveling fire and the restraint effect.","PeriodicalId":45033,"journal":{"name":"Journal of Structural Fire Engineering","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43652668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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