{"title":"Fire Response Analysis of Prefabricated Combined Reinforced Concrete Beams Based on Finite Element Model Correction","authors":"Caiwei Liu, Shuqi Sun, Xuhong Huang, Jijun Miao, Xindi Zhang","doi":"10.1007/s10694-024-01621-w","DOIUrl":"10.1007/s10694-024-01621-w","url":null,"abstract":"<div><p>To obtain an accurate finite element model (FEM) for response analysis of prefabricated combined reinforced concrete beam (PCRCB) under fire exposure, a stepwise FEM correction method is proposed based on the improved response surface method. Four T-shaped PCRCBs were designed and cast to verify the accuracy and practicality of the proposed method. Firstly, based on the static and dynamic tests before fire exposure, the FEM was corrected using the proposed correction strategy. The proposed method is initially validated by comparing the modal responses. Subsequently, a fire test was carried out. The test phenomena, temperature field, mid-span deflection and dynamic response under fire were analyzed. Finally, considering the development of crack, the static and dynamic responses under fire exposure were further simulated based on the modified FEM. The results indicate that the established FEM can accurately simulate the structural response. The spanwise deflection and fundamental frequency exhibited nonlinear variations with fire exposure time, which were strongly influenced by the load ratio. The proposed model correction method establishes the basis for the detail response analysis of PCRCB during fire exposure.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"61 2","pages":"449 - 481"},"PeriodicalIF":2.3,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10694-024-01621-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Research on the Behavior on Axial Tensile Welded Hollow Spherical Joints Exposed to Elevated Temperature","authors":"Xiaobin Qiu, Bingsheng Huang, Zhen Zhang, Haoyu Song, Yusheng Qin","doi":"10.1007/s10694-024-01618-5","DOIUrl":"10.1007/s10694-024-01618-5","url":null,"abstract":"<div><p>Welded hollow spherical joints (WHSJs) are commonly used joints in grid structures, and their mechanical behavior under fire will directly affect the service life and safety behavior of grid structures. Therefore, the WHSJs were heated to the specified high temperature, and the tensile experiments were performed on non-stiffened WHSJs exposed to elevated temperatures. The failure modes, axial load–displacement curves, and mechanical behavior of the non-stiffened WHSJs exposed to elevated temperature were obtained. The experiment indicates that the failure mode of the axial tensile non-stiffened WHSJs is a pull-out failure. With the increase of heating temperature, the mechanical behavior of non-stiffened WHSJs gradually declines. The ductility of the non-stiffened WHSJs gradually increases with the heating temperature. Compared with the existing studies, the load-bearing capacity reduction trend of WHSJ exposed to elevated temperature is basically similar, and the stiffener has basically no function to improve the behavior of tensile WHSJs exposed to elevated temperature. The reliability of the numerical simulation was proved by comparison with experiments. According to the finite element analysis, the design method for the mechanical behavior of the non-stiffened WHSJs subjected to axial tension exposed to elevated temperature was proposed.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"61 2","pages":"381 - 410"},"PeriodicalIF":2.3,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141882258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fire TechnologyPub Date : 2024-08-01DOI: 10.1007/s10694-024-01612-x
Yanqiu Chen, Yifan Nie, Jiwei Zhang, Yi Zhao, Yuchun Zhang
{"title":"Experimental Dimension and Boundary Analysis of Upward Flame Spread Over U-Shaped Facade in Energy-Saving Building Fires","authors":"Yanqiu Chen, Yifan Nie, Jiwei Zhang, Yi Zhao, Yuchun Zhang","doi":"10.1007/s10694-024-01612-x","DOIUrl":"10.1007/s10694-024-01612-x","url":null,"abstract":"<div><p>Insulation layer is usually used in building facade for energy-saving design, and it also endangers the human safety in buildings due to its combustibility. U-shaped facade is a commonly used structure form in high-rise buildings for energy-saving design since it could improve both the light and ventilation conditions indoors. Through a series of experiments, this paper investigated the flame spread over insulation in u-shaped building facade fires under effect of structural dimensions (back wall length <i>W</i>, side wall length <i>L</i>, height <i>H</i>) and boundary conditions based on the flame spread rate, temperature and heat flow. It was found that the flame spread rate <i>V</i><sub><i>f</i></sub>, the temperature rise Δ<i>T</i> and the heat flow <i>q</i> over u-shaped facade were all positively correlated with the side wall length <i>L</i> and structural height <i>H</i>, while they were negatively correlated with the back wall length <i>W</i>. On the other hand, the lateral air entrainment restriction and flame interaction were both significantly increased the temperature and heat flow, strengthened the thermal feedback, accelerated the flame spread. However, the bottom air entrainment restriction slowed down the flame spread. Further, a modified structure factor was introduced to comprehensively analyze the influence of <i>L</i>, <i>W</i> and <i>H</i> on flame spread behavior over u-shaped structures, and the theoretical equations of <i>V</i><sub><i>f</i></sub><sup>*</sup>, Δ<i>T</i><sup>*</sup><sub>max</sub> and <i>q′</i><sup>*</sup><sub>max</sub> were established. This study provides theoretical basis and technical guidance for the fire prevention design of building facade covered with insulation.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"61 2","pages":"343 - 361"},"PeriodicalIF":2.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10694-024-01612-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141873230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Experimental Study on Foam Spreading on Fuel Layers with Different Thicknesses","authors":"Fengyuan Tian, Jun Fang, Hassan Raza Shah, Xuqing Lang, Zhijian Tian, Fei Tang","doi":"10.1007/s10694-024-01610-z","DOIUrl":"https://doi.org/10.1007/s10694-024-01610-z","url":null,"abstract":"<p>Fire-fighting foam has been widely used as a kind of efficient clean liquid fire extinguishing agent. The spreading of foam is an important index to evaluate the fire suppression performance of foam, which determines whether the foam can quickly cover the whole pool surface in the fire extinguishment process, effectively inhibit evaporation and isolate oxygen. In this work, the foam spreading experiments on the surface of fuel layer with different thicknesses (3–15 mm) were carried out. The results indicate that the decrease of the thickness of the fuel layer could slow down the foam spreading. There is a saturation thickness, beyond which the fuel layer thickness no longer affects foam spreading, because the flow in the fuel layer is transformed from Couette flow to boundary layer flow. Meanwhile, both the increase in the foam flow rate and decrease in the expansion ratio reduce the effect of fuel layer thickness on foam spreading. And at a foam flow rate of 14 L/min or expansion ratio of 5.5, the foam spreading is scarcely affected by the thickness of the fuel. Furthermore, it was found that the foam with smaller expansion ratio spreads faster than that of the lager expansion ratio due to larger pressure gradient at the same foam thickness. The work presented here enhances the understanding of the spread of foam over fuel.</p>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"36 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141882259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fire TechnologyPub Date : 2024-07-31DOI: 10.1007/s10694-024-01620-x
Daiqiang Zhu, Pai Xu, Yixian Liu, Rongjun Xing, Linjie Li
{"title":"The Smoke Flow Deflection Angles in Immersed Tunnel Fires with Multi-Point Concentrated Smoke Exhaust Mode: Representation Model and Influencing Mechanisms","authors":"Daiqiang Zhu, Pai Xu, Yixian Liu, Rongjun Xing, Linjie Li","doi":"10.1007/s10694-024-01620-x","DOIUrl":"10.1007/s10694-024-01620-x","url":null,"abstract":"<div><p>The smoke flows from the tunnel to the exhaust vent, and then to the exhaust duct under the multi-point concentrated smoke exhaust mode of immersed tunnel fires. This will cause resistance and energy loss by forming smoke flow deflection angles, which is the angle between the direction of smoke flow velocity and the longitudinal direction. In this study, the correlations between the smoke flow deflection angles and mechanical characteristics are revealed. Specifically, the smoke exhaust processes are divided into \"from the tunnel to the exhaust vent\" and \"from the exhaust vent to the exhaust duct\". Based on the dimensionless analysis, the presentation model with influencing factors of smoke flow deflection angles is established. Through numerical simulation, the influencing mechanisms of longitudinal ventilation velocity, exhaust volume flow rate, and distance of multi-point exhaust vents on the smoke flow are analyzed in a three-lane immersed tunnel under 50 MW. The quantitative relationships between the smoke flow deflection angle and factors are obtained. The correlations between the smoke flow deflection angles and component forces are established. The results show that smoke flow deflection angles are affected by the transverse and longitudinal forces. Additionally, the influence of longitudinal ventilation velocity and exhaust volume flow rate is related to the distance of the exhaust vent group from the fire source. Furthermore, the increase in the smoke flow deflection angle is not determined by the distance of the exhaust vent group from the fire source, but rather by the distance of the multi-point exhaust vents.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"61 2","pages":"411 - 448"},"PeriodicalIF":2.3,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10694-024-01620-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141873229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fire TechnologyPub Date : 2024-07-30DOI: 10.1007/s10694-024-01604-x
Qize He, Pengfei Ding, Yun Yang
{"title":"Characterization and Evaluation of Fire Response Performance in Shanghai Based on Fire Department Statistics","authors":"Qize He, Pengfei Ding, Yun Yang","doi":"10.1007/s10694-024-01604-x","DOIUrl":"10.1007/s10694-024-01604-x","url":null,"abstract":"<div><p>The efficiency of the emergency response plays a crucial role in both fire suppression and personnel rescue operations, where the travel time and speed are determined. However, there is limited research on the factors that influence travel time and speed, especially in the quantitative influences of time, space, and incident classification factors. In this work, the distribution of all incidents in Shanghai, 2022 are presented. The correlation of temporal factors such as time, date, and month, spatial factors such as distance to the city center, economic scale, population, and incident classification is studied and discussed. The results reveal that as the urgency of incidents increases, the travel time and speed tend to decrease and increase respectively. In the early morning, despite favorable traffic conditions, actual travel time significantly increases due to firefighter fatigue, resulting in a notable decrease in travel speed. During the lockdown period in March, April, and May for Covid-19 pandemic, there is a significant decrease in travel time and an increase in travel speed. Regarding spatial factors, there is a distinct regional distribution of actual travel time strongly correlated with area size, distance to the city center, and average travel distance. Notably, the relative speed difference between firefighting vehicles and regular vehicles increases as the incident type changes from fire to emergency rescues and social assistance. This speed difference is primarily influenced by the economic and population scale of the coverage area. As the severity level increases from Level 0 (lowest) to Level 5 (highest), travel time significantly decreases, while travel speed and relative speed difference markedly increase. The work will contribute to the theoretical foundation for fire station planning.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"61 2","pages":"275 - 293"},"PeriodicalIF":2.3,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10694-024-01604-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141873231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fire TechnologyPub Date : 2024-07-30DOI: 10.1007/s10694-024-01624-7
Louis Hardy, Anthony Collin, Mathieu Suzanne, Giacomo Erez, Rabah Mehaddi, Pascal Boulet
{"title":"Study of the Interactions Between a Water Spray and a Moving Layer of Hot Smoke","authors":"Louis Hardy, Anthony Collin, Mathieu Suzanne, Giacomo Erez, Rabah Mehaddi, Pascal Boulet","doi":"10.1007/s10694-024-01624-7","DOIUrl":"10.1007/s10694-024-01624-7","url":null,"abstract":"<div><p>This study compares the effects on a smoke layer of water sprays injected downward, upward or according to an inclined counter-flow configuration. The impact is analyzed considering stratification, mixing and cooling effects upstream (fire side) and downstream (opening side) the position of the spray. The experiments were conducted in a 1/5th scale model reproducing a room connected to a corridor. The injection of the poly-dispersed spray was carried out in the corridor where a layer of smoke was flowing in the upper part. Thanks to the experimental configuration, there is no direct impact of the spray on the fire source and the production of smoke, but only on the hot flow of smoke. The effect of the spray was evaluated for the different directions of injection and two water feeding pressures. The measurements have shown that effective cooling of the upper layer is observed downstream of the spray. The efficiency of the cooling is dependent on the injection angle. A more or less significant heating of the lower layer is measured upstream for all the injection angles. The injection angle has an influence on the smoke mixing and cooling, an upward spray injection—either vertical or inclined—being more impactful. The strongest interaction is observed for an inclined counter-flow injection, similar to the configuration of firefighters cooling a smoke layer while moving forward in a corridor toward a fire source. Moreover, two water injection pressures were investigated: 4 and 8 bars. Increasing this pressure reduces the droplet diameter and increases the water flow rate. In the present experimental configuration, modifying the water injection pressure showed an effect, yet limited because the droplet size distribution was not strongly impacted. All experimental data are available in an open-access database for further uses.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"61 2","pages":"513 - 540"},"PeriodicalIF":2.3,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10694-024-01624-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141871936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fire TechnologyPub Date : 2024-07-30DOI: 10.1007/s10694-024-01622-9
Wei Chu, Jun Fang, Yahong Yang, Shangqing Tao, Hassan Raza Shah, Mengwen Wang, Yu Wang
{"title":"Reaction to Fire of the Timber Structure Encapsulated by Multilayer Mortar Coating Under Uniform Thermal Loading","authors":"Wei Chu, Jun Fang, Yahong Yang, Shangqing Tao, Hassan Raza Shah, Mengwen Wang, Yu Wang","doi":"10.1007/s10694-024-01622-9","DOIUrl":"10.1007/s10694-024-01622-9","url":null,"abstract":"<div><p>Encapsulation is an effective method for enhancing the reaction to fire of timber structures. Mortar coatings are widely used to encapsulate traditional timber structures due to their excellent mechanical properties. However, there is a significant lack of data on the reaction to fire and fire mechanisms of timber structures with mortar encapsulation, and little is known about the influence of mortar composition on the burning characteristics of timber substrates. This study investigated the fire properties of organic–inorganic composite multilayer mortar coatings with fibre-reinforced layers commonly employed in encapsulating traditional Chinese wooden structures. The burning phases of timber encapsulated by multilayer mortar coatings were examined using thermogravimetric analysis and constant radiation ignition experiments. The fire propagation apparatus was used to measure the critical fire parameters of the encapsulated timber structures, including ignition time, heat release rate, total heat release, and time to peak heat release rate under a constant radiation heat flux of 30 kW/m<sup>2</sup>. Comparative experiments between finished and semi-finished coating encapsulated samples were conducted to investigate the influence of coating composition. The cracking behaviour of the coating was synchronously observed, with crack length analysis using image recognition techniques. It was found that the topcoat property of the coating mainly influenced the ignition time, and adding the fibre layer can effectively inhibit the bending of the timber substrate. Additionally, reducing the aggregate size may effectively prolong the time to reach the peak of the heat release rate. The relationship between the rise in heat release rate in encapsulation coatings, the appearance of surface cracks, and the maximum crack length with the heat release rate peak has been well established.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"61 1","pages":"183 - 212"},"PeriodicalIF":2.3,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141871937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fire TechnologyPub Date : 2024-07-27DOI: 10.1007/s10694-024-01617-6
Z. Acem, V. Dréan, G. Parent, A. Collin, A. Wilhelm, T. Beji, R. Mehaddi
{"title":"Water Sprays Cooling of a Hot Metallic Plate","authors":"Z. Acem, V. Dréan, G. Parent, A. Collin, A. Wilhelm, T. Beji, R. Mehaddi","doi":"10.1007/s10694-024-01617-6","DOIUrl":"10.1007/s10694-024-01617-6","url":null,"abstract":"<div><p>In the present work, spray cooling experiments of a hot steel plate were carried out with three different nozzles in order to provide accurate experimental data for the modellers. Special attention was paid to for both the measurement of the surface temperatures and the characterization of the sprays. Firstly, the surface temperatures were measured using K-type thermocouple wires welded directly to the surface of the plate in a separate contact. This technique provides an accurate measurement of the surface temperature during the cooling. Secondly, the spray characteristics of each nozzle were also thoroughly investigated. It was found that the droplet size and velocity distributions of each nozzle followed a log-normal law. The corresponding Sauter mean diameter (SMD) and mean velocity ranged from 170 to 230 µm and from 5.6 m s<sup>−1</sup> to 22.4 m s<sup>−1</sup>, respectively. Spray cooling was started after heating the plate between 500°C and 600°C using a radiant panel. Cooling rates were very high and the time to reach ambient temperature varied from 4 s to 1 min depending on the nozzle used. Heat Flux (<span>({dot{q}}^{{prime}{prime}})</span>) and Heat Transfer Coefficient (HTC) were calculated from the temperature data. It was found that high levels of critical heat flux (CHF), around 9 MW m<sup>−2</sup>, were achieved for two of the three nozzles studied, including the one with the lowest flow rate of only 1.6 L min<sup>−1</sup>. Finally, the results obtained in this study could be used to validate numerical codes such as FDS and FireFOAM, which are commonly used in fire safety engineering.</p></div>","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"61 2","pages":"363 - 379"},"PeriodicalIF":2.3,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141772777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fire TechnologyPub Date : 2024-07-26DOI: 10.1007/s10694-024-01615-8
Seyed Javad Mortazavi, Iman Mansouri, Alireza Farzampour, Eleni Retzepis, Jong Wan Hu
{"title":"Correction: Evaluation of the Fire Behavior of Low-Rise Eccentrically Braced Frame Structures Under Different Fire Scenarios","authors":"Seyed Javad Mortazavi, Iman Mansouri, Alireza Farzampour, Eleni Retzepis, Jong Wan Hu","doi":"10.1007/s10694-024-01615-8","DOIUrl":"10.1007/s10694-024-01615-8","url":null,"abstract":"","PeriodicalId":558,"journal":{"name":"Fire Technology","volume":"60 6","pages":"4101 - 4101"},"PeriodicalIF":2.3,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141798686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}