Journal articles on the topic 'Steel, Structural Fire-testing'
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Qureshi, Ramla Karim, Negar Elhami-Khorasani, and Thomas Gernay. "Adaption of active boundary conditions in structural fire testing." Journal of Structural Fire Engineering 10, no. 4 (December 9, 2019): 504–28. http://dx.doi.org/10.1108/jsfe-12-2018-0042.
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Purpose This paper aims to investigate the need for active boundary conditions during fire testing of structural elements, review existing studies on hybrid fire testing (HFT), a technique that would ensure updating of boundary conditions during a fire test, and propose a compensation scheme to mitigate instabilities in the hybrid testing procedure. Design/methodology/approach The paper focuses on structural steel columns and starts with a detailed literature review of steel column fire tests in the past few decades with varying axial and rotational end restraints. The review is followed with new results from comparative numerical analyses of structural steel columns with various end constraints. HFT is then discussed as a potential solution to be adapted for fire testing of structural elements. Challenges in contemporary HFT procedures are discussed, and application of stiffness updating approaches is demonstrated. Findings The reviewed studies indicate that axial and rotational restraints at the boundaries considerably influence the fire response of steel columns. Equivalent static spring technique for simulating effect of surrounding frame on an isolated column behavior does not depict accurate buckling and post-buckling response. Additionally, numerical models that simulate fire performance of a column situated in a full-frame do follow the trends observed in actual test results up until failure occurs, but these simulations do not necessarily capture post-failure performance accurately. HFT can be used to capture proper boundary conditions during testing of isolated elements, as well as correct failure modes. However, existing studies showed cases with instabilities during HFT. This paper demonstrates that a different stiffness updates calculated from the force-displacement response history of test specimen at elevated temperature can be used to resolve stability issues. Originality/value The paper has two contributions: it suggests that the provision of active boundary conditions is needed in structural fire testing, as equivalent static spring does not necessarily capture the effect of surrounding frame on an isolated element during a fire test, and it shows that force-displacement response history of test specimen during HFT can be used in the form of a stiffness update to ensure test stability.
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Sunar Bükülmez, Pınar, and Oguz C. Celik. "Pre and post-fire mechanical properties of structural steel and concrete in steel-concrete composite cellular beams." MATEC Web of Conferences 282 (2019): 02054. http://dx.doi.org/10.1051/matecconf/201928202054.
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This paper presents an experimental investigation into possible variations of mechanical properties of structural steel and concrete in composite cellular beams exposed to ISO 834 fire and cooled down phases. Four full-scale fire tests were performed on protected and unprotected beams under assumed service loads. Tensile stress-strain behavior of steel coupons taken from the beams and compressive strengths of concrete cores taken from the reinforced concrete slabs are studied. Material coupon tests for steel are carried out as per TS EN ISO 6892-1. As for the concrete, compression tests were conducted. Coupon test results reveal that, after fire testing, a maximum reduction ratio of 65% in ultimate strain is obtained for the unprotected beam samples. This indicates that the reductions in the mechanical properties of steel in the protected beams are much less when compared to those of the unprotected beams. It is also found that the maximum increase in post-fire strength/pre-fire strength ratios for concrete is 11% for the unprotected beam, while a 20 % decrease is recorded for water based protected cellular beam. For the protected specimens, the RC slabs were exposed to higher temperatures, and the compressive strength of concrete after testing was lower than that of the unprotected beam slabs.
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Kwon, In Kyu. "Analysis of Structural Stability for H-Section Made of SM 400 According to Lengths and Boundary Conditions at High Temperatures." Applied Mechanics and Materials 543-547 (March 2014): 3857–60. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.3857.
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A fire can cause serious damage to steel framed buildings so most of countries have fire regulations specifying fire resistance for structural elements. Fire resistance generally has been evaluated by a limited size testing facility. However, the size of columns and beams are different based on various conditions. Especially, the height of column and boundary condition are the main factors that govern the fire resistance of structural elements. To make a basic database for the H-section made of an ordinary grade structural steel, SM 400, an analysis was conducted by using mechanical and thermal properties with a proper theory. The fact findings suggested that the fire resistance for longer and fixed to fixed column were required a new guide line for covering of fire protective materials.
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Xing, Zhe, Ou Zhao, Merih Kucukler, and Leroy Gardner. "Testing of stainless steel I-section columns in fire." Engineering Structures 227 (January 2021): 111320. http://dx.doi.org/10.1016/j.engstruct.2020.111320.
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Patton, Joel S. "Fire and Smoke Corrosivity of Structural Materials." Journal of Fire Sciences 10, no. 4 (July 1992): 294–322. http://dx.doi.org/10.1177/073490419201000403.
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The deleterious effects that combustion products generated dur ing fires can have on normal construction materials have been well-docu mented. The combined effects of fire, corrosive smoke and particulate have been defined as fire corrosivity. While the effects of fire corrosivity are well-known, little quantitative information is available concerning the mechanisms in volved and the degree to which materials, particularly metals, are susceptible. Consequently, a study which was conducted to begin examining the effects of fire and smoke corrosivity on metals is described and the results are presented. Various metal targets were exposed to corrosive smoke and fire particulate pro duced from polyvinylchloride (PVC) samples burned in a cone calorimeter. The target materials consisted of 304 stainless steel, 1010 carbon steel and 70-30 CuNi alloy. In addition to metal targets, electrical resistance probes were also utilized in the testing to monitor in-situ corrosion rates. The probe materials corresponded to the metal targets so that a comparison could be conducted. After testing, both the metal targets and corrosion probes were sectioned and prepared for analysis using standard metallographic techniques. The targets and probes were analyzed for corrosion products and depth of attack. Results from this testing show that all the metal targets proved highly susceptible to the effects of fire and smoke corrosivity attributed to the burning of PVC samples. These results are presented and compared by corrosion rates. In addi tion, the performance of the corrosion probes in terms of their ability to produce accurate corrosion measurements was evaluated by comparing their corrosion depth measurements to those of the metal targets. It can be concluded from these observations that the testing of structural metals for their resistance to fire corrosivity must be done over a wide range of combustion environments us ing a large number of targets in order to generate a statistical basis before any predictions can be made concerning a particular alloy's resistance.
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Ng, Yan Hao, Indraneel Suhas Zope, Aravind Dasari, and Kang Hai Tan. "Correlating the Performance of a Fire-Retardant Coating across Different Scales of Testing." Polymers 12, no. 10 (October 2, 2020): 2271. http://dx.doi.org/10.3390/polym12102271.
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Material-scale tests involving milligrams of samples are used to optimize fire-retardant coating formulations, but actual applications of these coatings require them to be assessed with structural-scale fire tests. This significant difference in the scale of testing (milligrams to kilograms of sample) raises many questions on the relations between the inherent flammability and thermal characteristics of the coating materials and their “performance” at the structural scale. Moreover, the expected “performance” requirements and the definition of “performance” varies at different scales. In this regard, the pathway is not established when designing and formulating fire-retardant coatings for structural steel sections or members. This manuscript explores the fundamental relationships across different scales of testing with the help of a fire-protective system based on acrylic resin with a typical combination of intumescent additives, viz. ammonium polyphosphate, pentaerythritol, and expandable graphite. One of the main outcomes of this work dictates that higher heat release rate values and larger amounts of material participating in the pyrolysis process per unit time will result in a rapid rise in steel substrate temperature. This information is very useful in the design and development of generic fire-retardant coatings.
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Gardner, L., and N. R. Baddoo. "Fire testing and design of stainless steel structures." Journal of Constructional Steel Research 62, no. 6 (June 2006): 532–43. http://dx.doi.org/10.1016/j.jcsr.2005.09.009.
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Golovanov, V. I., G. I. Kryuchkov, A. N. Strekalev, A. A. Komissarov, and S. M. Tikhonov. "A study on mechanical properties of modern rolled structural metal at elevated temperatures." Pozharovzryvobezopasnost/Fire and Explosion Safety 31, no. 2 (June 3, 2022): 52–62. http://dx.doi.org/10.22227/0869-7493.2022.31.02.52-62.
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Introduction. The purpose of this work is to obtain experimental data on the numerical dependence between the strength characteristics of the most widely used grades of rolled structural metal products (including those featuring high heat resistance) and a critical increase in temperature.Materials and methods. As the subject of research we used specimens of rolled metal of the following strength classes: С255 (steel St3sp), С345 (steel 09G2S), С390 (steel 14G2), and rolled metal that had high heat resistance properties S355P (steel 06MBF). Small cylindrical specimens of type B, with M10 thread on heads and the working diameter of 4 mm were used to conduct the static tension and compression tests of mechanical properties. The procedure encompassed the heating of the specimens to the pre-set testing temperature at the rate of not more than 10 °C/min, their 15-minute exposure, and testing for static uniaxial tension/compression.Results and discussion. The results of the experimental research on mechanical properties of different widely used grades of rolled structural steel, including heat resistant rolled metal, subjected to the fire impact, are presented in the article. The data are presented in the form of diagrams used to make a quantitative assessment of the effect of elevated temperature on the strength properties of rolled structural metal under the impact of fire. This information can be contributed to the design and operation of structural metal constructions to develop analytical methods of identifying the fire-resistance limits of constructions made of structural metal.Conclusion. The new data on the fire resistance of metal products allow for a more reasonable building design, higher safety and resistance of buildings and structures to the effect of fire. A wider area of application of the whole range of rolled products featuring higher heat resistance will reduce metal consumption and construction costs, boost competitiveness and attractiveness of steel structures and their application in the construction of buildings and structures of various purposes.
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Cirpici, Burak Kaan. "Predicting and comparing the fire performance of a small-scale composite structure." Challenge Journal of Concrete Research Letters 12, no. 3 (September 15, 2021): 72. http://dx.doi.org/10.20528/cjcrl.2021.03.001.
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The purpose of this paper is to investigate a strategy for the fire testing of reduced scale structural models which will help engineers design safer structures and reduce the loss from fires. The concept of this work is how composite frame floor arrangements, beam-column connections might be modelled at a small scale suitable for fire testing. Testing full-scale is expensive, besides the testing of scaled model produces reasonable results which help us to understand the failure mechanism and all significant thermo-structural responses involved in a fire. Thermal effects within a structural element generate fire curve, thermal input and structural displacement output, in other words cause and impact. Dimensional analysis, which is a condition for dynamic similarity between prototype and model, can be achieved when all the dimensionless groups are set equal for both model and prototype. On the other hand, scaling rules are used to decide how much insulating material will be used on a structure. 5-storey composite building with composite floors and steel columns has been modelled at small scale with 1/5. The obtained results from various parametric investigations show that the reduced scale model fire test method would be a feasible way to investigate the fire performance of composite structures.
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Salem, Osama, George Hadjisophocleous, and Ehab Zalok. "Structural Fire Performance of Innovative Moment-Resisting Connection Joining Steel Beams to HSS Columns." Journal of Structural Fire Engineering 5, no. 4 (November 18, 2014): 331–52. http://dx.doi.org/10.1260/2040-2317.5.4.331.
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In this paper, experimental results of the structural fire behaviour of four large-scale steel frame test assemblies are presented. Test assemblies were made of HSS beams and columns connected together using an innovative extended end-plate moment connection configuration. Two different parameters were investigated, the connection end plate thickness and the degree of beam axial restraint. The fire performance of this beam-to-column configuration was compared to the behaviour of a commonly-used connection configuration with similar parameters and fire testing conditions. The newly-developed connection configuration behaved in a more flexible manner at elevated temperature than the regular configuration. In addition to improved constructability and pleasant appearance, the new connection configuration exhibits greater moment-carrying capacity and enhanced fire resistance characteristics.
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Budi Wijaya, Gunawan. "Comprehensive condition assessment program on the fire damaged structure - a project case in Singapore." MATEC Web of Conferences 195 (2018): 02034. http://dx.doi.org/10.1051/matecconf/201819502034.
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A fire damaged structure at the eastern part of Singapore was assessed. Some concrete spalling exposing corroded steel reinforcements were noted on the post tensioned concrete beam and reinforced concrete slab, raising a concern about the structural integrity of the overall floor. A comprehensive condition assessment was performed on the affected structural elements to determine the extent of the damage, which included some on-site destructive and non-destructive tests as well as some laboratory testing on the collected concrete and steel samples. Testing data revealed that the concrete was still in consistently good condition with the average residual compressive strength of 36.51MPa. Petrographic examinations suggested that the top 5mm of the concrete surface might be exposed to a temperature not more than 450o C. The steel reinforcement and post tension strands were found to be still in good condition as well. The findings of this assessment will then be used for further structural assessment to determine the most effective structural rehabilitation program.
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Xing, Zhe, Ou Zhao, Merih Kucukler, and Leroy Gardner. "Fire testing of austenitic stainless steel I-section beam–columns." Thin-Walled Structures 164 (July 2021): 107916. http://dx.doi.org/10.1016/j.tws.2021.107916.
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Shrih, Ali, Adeeb Rahman, and Mustafa Mahamid. "Behavior of ASTM A325 bolts under simulated fire conditions: experimental investigation." Journal of Structural Fire Engineering 8, no. 4 (December 11, 2017): 377–91. http://dx.doi.org/10.1108/jsfe-06-2016-0005.
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Purpose Heavy hex structural bolts have been used in a wide range of steel structures for many years. However, these structures remain susceptible to fire damage. Conducting fire experiments on full-scale steel structures is costly and requires specialized equipment. The main purpose of this research is to test, analyze and predict the behavior of ASTM A325 bolts under tension loading in simulated fire conditions and develop a reliable finite element model that can predict the response of similar bolts without the need for repeated testing. Design/methodology/approach The experimental work was conducted at the University of Wisconsin-Milwaukee, where an electric furnace was custom-built to test a bolted specimen in tension under elevated temperatures. A transient-state testing method was adopted to perform a group of tests on 12.7 mm (½”) – diameter A325 bolts. The tests were divided into two groups: the first one was used to calibrate the equipment and choose a final testing arrangement and the second group, consisting of four identical tests, was used to validate a finite element model. Findings The temperature-displacement and load-displacement response was recorded. The tested bolts exhibited a ductile fracture in which a cup-and-cone shaped failure surface was formed in the threaded section at the root of the nut. ASTM A325 bolts are widely used by engineers in building and bridge construction, the results of this research enable engineers to determine the behavior and strength of ASTM A325 bolts when such bolts when exposed to fire event. Research limitations/implications Structural bolts are used to connect structural members, and they are part of structural assembly. To study the behavior of the bolts, the bolts only were investigated in a fire simulated in a furnace. The bolts studied were not part of a structural assembly. Practical implications The results of this study enable engineers to evaluate the condition of ASTM A325 bolts when subjected to fire loading. Originality value Tests were conducted at the University of Wisconsin – Milwaukee’s structures laboratory to study the effect of fire on an ASTM A325 bolts. Many tests under fire loading have been performed by researchers on different components of steel structures, this study focuses on studying the behavior of ASTM A325 bolts which are widely used in the USA.
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Marx, Hendrig, and Richard Walls. "Thermal behaviour of a novel non-composite cellular beam floor system in fire." Journal of Structural Fire Engineering 10, no. 3 (September 9, 2019): 354–72. http://dx.doi.org/10.1108/jsfe-10-2018-0032.
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Purpose The Southern African Institute of Steel Construction has developed a novel cellular beam structure (CBS) for multi-storey buildings that is entirely devoid of concrete. Channel sections between the cellular beams support a complex sandwich flooring system, which contains a fire-resistant ceiling board, metal sheeting, an interior fibre-cement board and an access-flooring system. As for all structures, the CBS requires a fire rating. This paper aims to investigate the thermal behaviour of the CBS using numerical modelling and experimental fire testing, as it has a unique setup. Design/methodology/approach Experimental fire tests on the flooring system were conducted to validate finite element models, which were developed in ABAQUS. These models were then extended to include floor beams and the structural steelwork. Findings Good correlations were found between the experimental and numerical results, with temperature variations typically in the range of 0-5%, although with localised differences of up to 20%. This allowed larger finite element models, representing the sandwich floor system of the CBS, to be developed and analysed. A 1-hour rating can be obtained by the system in terms of insulation and integrity requirements. Practical implications The CBS allows for more economical steel structures, due to the rapid construction of its modular panels. A suitable fire resistance will ensure the safety of the occupants and prevent major structural damage. Steelwork and flooring temperatures are determined which has allowed for global structural analyses to be carried out. Originality/value The originality of this study lies in thermal analysis and testing of a new cellular beam flooring system, through determining behaviour in fire, along with beam temperatures.
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Shrih, Ali, Adeeb Rahman, and Mustafa Mahamid. "Finite element analysis of tension-loaded ASTM A325 bolts under simulated fire loading." Journal of Structural Fire Engineering 9, no. 1 (March 12, 2018): 2–18. http://dx.doi.org/10.1108/jsfe-06-2016-0006.
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Purpose Nuts and bolts have been used as fasteners of steel structures for many years. However, these structures remain susceptible to fire damage. While conducting fire experiments on steel structures is sometimes necessary, to better understand their behavior, such experiments remain costly and require specialized equipment and testing facilities. This paper aims to present a highly accurate three-dimensional (3D) finite element (FE) model of ASTM A325 bolt subjected to tension loading under simulated fire conditions. The FE model is compared to the results of experimental testing for verification purposes and is proven to predict the response of similar bolts up to certain temperatures without the need for repeated testing. Design/methodology/approach A parametric 3D FE model simulating tested specimens was constructed in the ANSYS Workbench environment. The model included the intricate details of the bolt and nut threads, as well as all the other components of the specimens. A pretension load, a tension force and a heat profile were applied to the model, and a nonlinear analysis was performed to simulate the experiments. Findings The results of the FE model were in good agreement with the experimental results, deviations of results between experimental and FE results were within acceptable range. This should allow studying the behavior of structural bolts without the need for expensive testing. Originality/value Detailed 3D FE models have been created by the authors have been created to study the behavior of structural bolts and compared with experiments conducted by the authors.
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Abeysiriwardena, Tharindu, and Mahen Mahendran. "Numerical modelling and fire testing of gypsum plasterboard sheathed cold-formed steel walls." Thin-Walled Structures 180 (November 2022): 109792. http://dx.doi.org/10.1016/j.tws.2022.109792.
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Shallal, Muhaned A., and Aqil Mousa K. Al Musawi. "Tests of Residual Shear Transfer Strength of Concrete Exposed to Fire." Archives of Civil Engineering 64, no. 2 (December 31, 2018): 187–99. http://dx.doi.org/10.2478/ace-2018-0024.
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AbstractReinforced concrete is one of the most widely used structural components about which much scientific research has been conducted; however, some of its characteristics still require further research. The main focus of this study is the effect of direct fire on the shear transfer strength of concrete. It was investigated under several parameters including concrete strength, number of stirrup legs (the steel area across the shear plane), and fire duration. The experimental program involved the testing of two sets (groups) of specimens (12 specimens each) with different concrete strengths. Each set contained specimens of two or four stirrup legs exposed to direct fire from one side (the fire was in an open area to simulate a real-life event) for a duration of one, two, and three hours. The results of the comparison showed the importance of using high-performance concrete (instead of increasing the number of stirrup legs) to resist shear stress for the purpose of safety. A significant reduction in shear strength occurred due to the deterioration of the concrete cover after three hours of direct fire exposure.
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Le and Tsai. "Experimental Assessment of the Fire Resistance Mechanisms of Timber–Steel Composites." Materials 12, no. 23 (December 2, 2019): 4003. http://dx.doi.org/10.3390/ma12234003.
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Hybrid structures known as timber–steel composites (TSCs) have been extensively studied due to their potential use as alternative construction materials that can satisfy demands related to sustainability. In addition to load capacity, fire resistance is a major consideration regarding the extensive use of TSCs. In this study, 12 specimens were tested using a glulam timber material covering cold-formed steel at the center. Specifically, the TSCs were fabricated from two timber blocks and an I-shaped steel core assembled using dowels or glue as a major structure. In order to use additional timber as a fire protection layer to protect a major structure by its charcoal produced after being burned, an additional timber with 5 cm in thickness was used to cover the major structure. The 1-h fire testing of TSC following the ISO 834-1 standard was applied, in order to achieve the potential application for a 4-story timber building. The results showed that temperatures at the steel flange increased by more than 300 °C for the final 5 min in 10 out of the 12 TSC specimens, indicating that the fire protection provided by the timber structure was not sufficient. The charcoal layer surpassing the extra timber was originally set and entered the steel structure of the TSC, which was expected to retain its physical qualities after a fire. Methods for evaluating the charring properties, based on the conventional method for wood and the standard specification set by Eurocode 5, were used to assess the structural degradation of TSCs. The conventional assessments showed a divergence from the actual performance of TSCs. Such variations demonstrated the limitations of models for conventional wood in assessing the structure of a TSC. A realistic assessment was conducted to expand knowledge related to this composite under destructive processes and provide fire reference values for the practical implementation of TSCs.
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Wang, Yu, Yong Jun Liu, and Lin Qi. "Experimental Research of Corner Joints in Steel-Framed Structures under Fire Conditions." Applied Mechanics and Materials 578-579 (July 2014): 374–77. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.374.
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The research involved experimental testing of simple steel connections and components (structural 8.8 bolts) at elevated temperatures. High temperature tests on structural bolts demonstrated two modes of failure at elevated temperatures: bolt breakage and thread stripping. In order to prevent the thread stripping in a connection,the manufacturing process of bolts and nuts has been investigated and the ‘over tapping’ of nut threads to accommodate the (zinc) coating layer for corrosion resistance has been indentified as a primary reason resulting in this premature failure between bolts and nuts. Experimental tests on endplate connections revealed the ductility of these connections to decrease at high temperatures, which might hinder the development of catenary actions in fire if plastic hinges are attempted to be formed within the connection zones. Component-based modelling and finite element simulation have been utilized for investigation of the performance of these connections.
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Xing, Zhe, Ou Zhao, Merih Kucukler, and Leroy Gardner. "Fire testing and design of slender stainless steel I-sections in weak-axis flexure." Thin-Walled Structures 171 (February 2022): 108682. http://dx.doi.org/10.1016/j.tws.2021.108682.
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Peng, Peng-Chi, Jen-Hao Chi, and Jyin-Wen Cheng. "A study on behavior of steel structures subjected to fire using non-destructive testing." Construction and Building Materials 128 (December 2016): 170–75. http://dx.doi.org/10.1016/j.conbuildmat.2016.07.056.
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Liu, Yong Jun, Qing Hong Zeng, Hong Ru Liu, and Shuo Xun Wang. "Experimental Study on Post Fire Tensile Properties of Reinforcing Rebars Connected by Grout-Filled Splice Sleeves." Key Engineering Materials 773 (July 2018): 305–10. http://dx.doi.org/10.4028/www.scientific.net/kem.773.305.
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This paper presents some experimental results of tensile properties of reinforcing bars spliced by grout-filled coupling sleeves after exposed to fires to identify the effect of temperature histories on tensile properties of spliced reinforcing bars, which provide a useful base for assessing structural behaviors of precast reinforced concrete buildings damaged by fires. A spliced rebar system investigated in this paper consists of two equal-diameter steel reinforcing bars with 25mm diameter and a straight coupling sleeve with 55mm outer and 42mm inner diameters. As a result, the thickness of grout between internal steel bars and outer sleeves are 8.5mm. Five test specimens are manufactured in identical technology and divided into three groups. First group is reference group consist of just one specimen which is not exposed to fire. Second and third groups consist of two specimens that are exposed to ISO 834 standard fire in furnace for 15 and 25 minutes respectively. The temperature-time curves of grout between rebars and sleeves are measured via thermocouples embedded in grout. Subsequently, a universal testing machine is used to test the ultimate load bearing capacities of five specimens. Test results demonstrate that ultimate load bearing capacities of steel rebars spliced by grout-filled sleeves are considerably reduced due to fire damaged grout.
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Okyay, Gizem, Fabienne Samyn, Maude Jimenez, and Serge Bourbigot. "A Facile Technique to Extract the Cross-Sectional Structure of Brittle Porous Chars from Intumescent Coatings." Polymers 11, no. 4 (April 9, 2019): 640. http://dx.doi.org/10.3390/polym11040640.
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Intumescent coatings are part of passive fire protection systems. In case of fire, they expand under thermal stimuli and reduce heat transfer rates. Their expansion mechanisms are more or less recognized, but the fire testing data shall be interpreted as function of coating morphology. Expansion ratios are examined together with the inner structures of specimens submitted to fire. Bare cutting techniques damage the highly porous and fibrous specimens because they become very crumbly due to charring. So far, absorption contrasted X-ray computed microtomography (CT) was used as a non-destructive technique. Nevertheless, access to X-ray platforms can be relatively expensive and scarce for regular use. Also, it has some drawbacks for carbon rich specimens strongly adhering on steel substrates because it leads sometimes to noisy images and lost data due to resolution limits on specimens reaching ten of centimeters. Therefore, we propose an inexpensive and more accessible experimental approach to observe those specimens with minimized structural damage under visible lighting. To that end, charred specimens were casted into pigmented epoxy resin. After surface treatments, color contrasted cross-sections could be observed under optical digital microscopy thanks to high level of interconnectivity of pores. Subsequent image treatments confirmed that the structural integrity was kept when compared to previous CT data. The proposed method is practical, cheaper and more accessible for the quantitative assessment of inner structure of charred brittle specimens.
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Bennetts, I. D., K. A. M. Moinuddin, C. C. Goh, and I. R. Thomas. "Testing and factors relevant to the evaluation of the structural adequacy of steel members within fire-resistant elevator shafts." Fire Safety Journal 40, no. 8 (November 2005): 698–727. http://dx.doi.org/10.1016/j.firesaf.2005.06.005.
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Ayyasamy, Leema Rose, Anbarasu Mohan, Dhanasingh Sivalinga Vijayan, Agoramoorthy Sattainathan Sharma, Parthiban Devarajan, and Aravindan Sivasuriyan. "Finite element analysis of behavior and ultimate strength of composite column." Science and Engineering of Composite Materials 29, no. 1 (January 1, 2022): 176–82. http://dx.doi.org/10.1515/secm-2022-0017.
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Abstract Composite sections are found to be a novel technique in modern day scenario of construction. This stands tall than the ordinary and conventional type of constructions. Columns as a structural element play a vital role in structural frame. This research comments on the behavior of composite columns. The main objective of this study is to analyze the behavior of steel-encased concrete composite columns as experimentally under axial compression and the mode of failure under ultimate failure and yield point. The steel-concrete composite system combines the formability and rigidity of reinforced concrete with the ductility and strength of structural steel to meet the demand for earthquake-resistant constructions. Three specimens were chosen for this study: one was a composite column, the other two were ordinary RC columns and structural steel columns. The raw materials' natural properties are assessed. As a result, material testing for cement, fine aggregate, and coarse aggregate was completed, as well as a concrete mix design. A comparative analysis of the local and post-local buckling behavior of different composite sections has been studied and the column sections have been designed according to Eurocode 4 (ENV 1994) to determine the plastic resistance of the section. These three specimens underwent compression test and the results are tabulated and compared. The corrosion resistance and fireproof nature (resistance to fire at higher temperatures) that are transmitted into the member are related to the steel being encased within the concrete. These are the two major drawbacks of any steel construction combined with an earthquake-resistant structure. Rather than a traditional steel construction, earthquake structures benefit from this type of load handling capabilities. The portion can be used before it completely collapses if proper design factors are taken into account.
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Zhong, Yukai, and Ou Zhao. "Concrete-filled high strength steel tube stub columns after exposure to fire: Testing, numerical modelling and design." Thin-Walled Structures 177 (August 2022): 109428. http://dx.doi.org/10.1016/j.tws.2022.109428.
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Kamath, Praveen, Umesh Sharma, Pradeep Bhargava, N. Bhandari, and Asif Usmani. "Mechanical Properties of Undamaged and Damaged Steel Rebars at Elevated Temperatures." Journal of Structural Fire Engineering 5, no. 3 (August 19, 2014): 251–60. http://dx.doi.org/10.1260/2040-2317.5.3.251.
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Evaluation of mechanical properties of undamaged and damaged steel rebars at elevated temperature finds its applications in development of steel material models likely to be used in designing reinforced concrete structural members subjected to earthquake triggered fire. In the present experimental investigation, 84 rebar specimens (cylindrical) of length 700 mm and diameters 8 mm, 10 mm, 16 mm and 20 mm were tested. Test specimens were prepared from the materials used in construction of full-scale reinforced concrete frame subjected to earthquake and fire. The specimens were initially stressed to a certain known limit (0.58 times yield stress fy) to simulate damage caused by an earthquake. After inducing the damage, they were exposed to a desired temperature level (20 °C, 250 °C, 500 °C and 750 °C) in a circular furnace arrangement coupled with a 400 kN universal testing machine. The temperature was sustained inside the furnace for about 30 minutes to ensure a steady state heat transfer inside the specimen. The bars were then tested under uniaxial tensile loading conditions to failure. The elongation was recorded by using two LVDTs fixed between gauge lengths of 265 mm at the mid-height. Results obtained in the tests were utilized to carry out multiple linear regression analysis and propose constitutive models for damaged steel rebars and various relationships: Tensile Strength, Peak-Strain, Elongation and Elastic Modulus vs. Temperature, Stress vs. Strain at elevated temperatures.
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Samir, Peter, and George Morcous. "Precast Prestressed Concrete Truss-Girder for Roof Applications." Journal of Structures 2014 (December 14, 2014): 1–13. http://dx.doi.org/10.1155/2014/524156.
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Steel trusses are the most popular system for supporting long-span roofs in commercial buildings, such as warehouses and aircraft hangars. There are several advantages of steel trusses, such as lightweight, ease of handling and erection, and geometric flexibility. However, they have some drawbacks, such as high material and maintenance cost, and low fire resistance. In this paper, a precast concrete truss is proposed as an alternative to steel trusses for spans up to 48 m (160 ft) without intermediate supports. The proposed design is easy to produce and has lower construction and maintenance costs than steel trusses. The truss consists of two segments that are formed using standard bridge girder forms with block-outs in the web which result in having diagonals and vertical members and reduces girder weight. The two segments are then connected using a wet joint and post-tensioned longitudinally to form a crowned truss. The proposed design optimizes the truss-girder member locations, cross-sections, and material use. A 9 m (30 ft) long truss specimen is constructed using self-consolidated concrete to investigate the constructability and structural capacity of the proposed design. A finite element analysis of the specimen is conducted to investigate stresses at truss diagonals, verticals, and connections. Testing results indicate the production and structural efficiency of the developed system.
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Wang, Zhenshan, Yanan Su, Jun Wei, Junlong Lu, and Xiaolei Li. "The Eccentric Compression Performance of Spirally Stiffened Thin-Walled Square Concrete-Filled Steel Tubular Laminated Composite Members." Buildings 12, no. 8 (August 3, 2022): 1151. http://dx.doi.org/10.3390/buildings12081151.
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To enhance the local buckling resistance of thin-walled steel pipes and enhance their fire and corrosion resistance, a new spirally stiffened thin-walled square concrete-filled steel tubular laminated composite member with transverse ribs is proposed. Through the four forms of combined members for eccentric pressure testing, it was found that: ordinary thin-walled steel pipe concrete drum buckling is more severe; with spiral ribs, the buckling is limited between the stiffening ribs; and the deformation is significantly reduced. By addressing the problem of cooperative work between the inner and outer structural layers of new components, it was found that, after setting constraints such as steel bars, the integrity of the two can be ensured, and the stress performance is significantly improved; compared to ordinary steel pipe concrete, the load-carrying capacity is 17.9% higher, and the deformation capacity is roughly equivalent. Spiral ribs as a new form of spatial restraint, in addition to increasing the local bending stiffness, manifest an overall restraint role in limiting lateral deformation of the steel pipe, whereas the role of vertical stiffness is insignificant. Based on test evidence, the influences of the width to thickness ratio of spiral ribs and pitch were determined, and reasonable structural measures for the members were given. Through the N–M relationship curve, the limit of damage in compression and tension under eccentricity was obtained at an eccentricity of about 0.9. Finally, a method for calculating the eccentric compressive ultimate load capacity of this new composite member was proposed.
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Nassif, Ayman Y., Isamu Yoshitake, and Ahmed Allam. "Full-scale fire testing and numerical modelling of the transient thermo-mechanical behaviour of steel-stud gypsum board partition walls." Construction and Building Materials 59 (May 2014): 51–61. http://dx.doi.org/10.1016/j.conbuildmat.2014.02.027.
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Hutchinson, Tara C., Xiang Wang, Gilbert Hegemier, Praveen Kamath, and Brian Meacham. "Earthquake and Postearthquake Fire Testing of a Midrise Cold-Formed Steel-Framed Building. I: Building Response and Physical Damage." Journal of Structural Engineering 147, no. 9 (September 2021): 04021125. http://dx.doi.org/10.1061/(asce)st.1943-541x.0003097.
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Naser, Mohannad, Rami Hawileh, and Hayder Rasheed. "Performance of RC T-Beams Externally Strengthened with CFRP Laminates under Elevated Temperatures." Journal of Structural Fire Engineering 5, no. 1 (March 1, 2014): 1–24. http://dx.doi.org/10.1260/2040-2317.5.1.1.
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This paper presents a numerical study that investigates the performance of reinforced concrete (RC) T-beams externally strengthened with carbon fibre reinforced polymer (CFRP) plates when subjected to fire loading. A finite element (FE) model is developed and a coupled thermal-stress analysis was performed on a RC beam externally strengthened with a CFRP plate tested by other investigators. The spread of temperature at the CFRP-concrete interface and reinforcing steel, as well as the mid-span deflection response is compared to the measured experimental data. Overall, good agreement between the measured and predicted data is observed. The validated model was then used in an extensive parametric study to further investigate the effect of several parameters on the performance of CFRP externally strengthened RC beams under elevated temperatures. The variables of the parametric study include applying different fire curves and scenarios, different applied live load combinations as well as the effect of using different insulation schemes with different types and thicknesses. Several observations and conclusions were drawn from the parametric investigation. It could be concluded that successful FE modeling of this structural member when exposed to thermal and mechanical loading would provide a valid economical and efficient alternative solution to the expensive and time consuming experimental testing.
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Wang, Xiang, and Tara C. Hutchinson. "Earthquake and Postearthquake Fire Testing of a Midrise Cold-Formed Steel-Framed Building. II: Shear Wall Behavior and Design Implications." Journal of Structural Engineering 147, no. 9 (September 2021): 04021126. http://dx.doi.org/10.1061/(asce)st.1943-541x.0003098.
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Woldemariam, Abraham Mengesha, Walter O. Oyawa, and Timothy Nyomboi. "Structural Performance of uPVC Confined Concrete Equivalent Cylinders Under Axial Compression Loads." Buildings 9, no. 4 (April 14, 2019): 82. http://dx.doi.org/10.3390/buildings9040082.
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There is always a need for more durable, ductile, and robust materials for buildings, bridges, and other infrastructure due to the drawbacks of existing construction materials. Some of the drawbacks are the corrosion of steel, the brittle failure of concrete, and the performance instabilities that are caused when exposed to different environments. Thus, an innovative system is required to improve the performance and retain the integrity of structures in a harsh environment. To alleviate the situation, Un-plasticized polyvinyl chloride (uPVC) tubes are used as a confining material and their performance was experimentally evaluated by testing uPVC confined equivalent cylinders. Accordingly, unconfined and uPVC confined equivalent concrete cylinders for five different concrete classes, four types of uPVC tube sizes, and the aspect ratios of two (h/D = 2) were prepared and tested under axial compression loads. The result shows that the uPVC confinement increased the strength, ductility factor, and energy absorption in between 1.28–2.35, 1.84–15.3, and 11–243 times the unconfined levels, respectively. The confinement performed well for lower concrete classes and higher thickness to diameter ratios (2t/D). The post-peak behavior of the stress-strain curve was affected by the 2t/D ratio and the absolute value of the slope decreased as the 2t/D ratio increased. Additionally, the uPVC tube has shown several advantages, such as acting as a permanent formwork, protecting the concrete from chemical attacks, preventing the segregation of concrete, preventing peeling, and taking off concrete cover, decreasing the cross-section, and resulting in lighter sections. The uPVC confinement provided a remarkable improvement on the strength, ductility, energy absorption, and post-peak behavior of concrete. Therefore, uPVC tubes can be used as confining material for bridge piers, piles, electric poles, and highway signboards, where the fire risk is very small, though additional research is required on fire resistance mechanisms, such as wire-mesh reinforced mortar cover.
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Rafi, Muhammad Masood, Abdul Basit Dahar, and Tariq Aziz. "High temperature mechanical properties of steel bars available in Pakistan." Journal of Structural Fire Engineering 9, no. 3 (September 10, 2018): 203–21. http://dx.doi.org/10.1108/jsfe-06-2017-0035.
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Purpose The purpose of this paper is to present the results of experimental testing of steel rebars at elevated temperatures. Three types of bars available in the local market in Pakistan were used. These data are not available in Pakistan. Design/methodology/approach Three types of bars were used, which included cold-twisted ribbed (CTR), hot-rolled deformed (HRD) and thermo-mechanically treated (TMT) bars. The diameter of the bar of each type was 16 mm. The bars were heated in an electrical furnace at temperatures which were varied from 100°C to 900°C in increment of 100°C. Bars of each type were also tested at ambient temperature as control specimens. The change of strength, strain and modulus of elasticity of the bars at high temperatures were determined. Findings The mechanical properties of the bars were nearly unaffected by the temperatures up to 200°C. CTR bars did not show yield plateau and strain hardening both at ambient and high temperatures. The high temperature yield strength and elastic modulus for all the three types of bars were similar at all temperatures. The yield plateau of both the HRD and TMT bars disappeared at temperatures greater than 300°C. The ultimate strength at high temperature of the HRD and TMT bars was also similar. The behaviours of the HRD and TMT bars changed to brittle beyond 400°C as compared to their behaviours at ambient temperature. The CTR bars exhibited ductile characteristics at failure at all the exposure temperatures relative to their behaviour at ambient temperature. Research limitations/implications The parameters of the paper included the rebar type and heating temperature and the effects of temperature on strength and stiffness properties of the steel bars. Practical implications Building fire incidents have increased in Pakistan. As reinforced concrete (RC) buildings exist in the country in significant numbers, the data related to elevated temperature properties of steel is required. These data are not available in Pakistan presently. The presented paper aims at providing this information for the design engineers to enable them to assess and increase fire resistance of RC structural members. Originality/value The presented paper is unique in its nature in that there is no published contribution to date, to the best of authors’ knowledge, which has been carried out to assess the temperature-dependent mechanical properties of steel reinforcing bars available in Pakistan.
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Ashteyat, Ahmed, Yasmeen T. Obaidat, Yasmin Z. Murad, and Rami Haddad. "COMPRESSIVE STRENGTH PREDICTION OF LIGHTWEIGHT SHORT COLUMNS AT ELEVATED TEMPERATURE USING GENE EXPRESSION PROGRAMING AND ARTIFICIAL NEURAL NETWORK." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 26, no. 2 (February 10, 2020): 189–99. http://dx.doi.org/10.3846/jcem.2020.11931.
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The experimental behavior of reinforced concrete elements exposed to fire is limited in the literature. Although there are few experimental programs that investigate the behavior of lightweight short columns, there is still a lack of formulation that can accurately predict their ultimate load at elevated temperature. Thus, new equations are proposed in this study to predict the compressive strength of the lightweight short column using Gene Expression Programming (GEP) and Artificial neural networks (ANN). A total of 83 data set is used to establish GEP and ANN models where 70% of the data are used for training and 30% of the data are used for validation and testing. The predicting variables are temperature, concrete compressive strength, steel yield strength, and spacing between stirrups. The developed models are compared with the ACI equation for short columns. The results have shown that the GEP and ANN models have a strong potential to predict the compressive strength of the lightweight short column. The predicted compressive strengths of short lightweight columns using the GEP and ANN models are closer to the experimental results than that obtained using the ACI equations.
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Turzó, Gábor, Ildikó-Renáta Száva, Sándor Dancsó, Ioan Száva, Sorin Vlase, Violeta Munteanu, Teofil Gălățeanu, and Zsolt Asztalos. "A New Approach in Heat Transfer Analysis: Reduced-Scale Straight Bars with Massive and Square-Tubular Cross-Sections." Mathematics 10, no. 19 (October 8, 2022): 3680. http://dx.doi.org/10.3390/math10193680.
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This paper reports experimental and theoretical result derived from research on steel structural elements’ fire-protection with intumescent paint. The experimental results were obtained by means of an original testing bench, briefly described below and some basic cases, i.e., horizontally and vertically disposed, massive and square-tubular cross-sectioned, reduced-scale straight bars heated at one end. By means of the thermocouples mounted along the bars, the temperature distribution laws were monitored, depending on the heated end’s nominal temperature. The paper describes an original approach to the temperature distribution evaluation by means of some new parameters, based on the temperature distribution laws experimentally obtained with reduced-scale models. We involved the least-square method (LSM) and the curve-fitting one in order to obtain a more accurate temperature distribution law compared to the experimentally obtained ones. We also introduced some new parameters in order to define the amount of heat loss in a more accurate way. Based on the results obtained, the authors suggest that this approach to the temperature distribution law can be efficiently applied in further thermal analyses, for both 2D and 3D structures. The paper also includes a thorough analysis of “m” variation along the square-tubular-cross-section, reduced-scale straight bars, and similar new approaches are proposed by the authors. The sub-goals of this investigation were (1) to obtain useful correlations between the magnitudes of the massivity ζ=P/A and the parameter “m” along the bar, and (2) to analyze, on reduced-scale models, the heat distribution laws on unprotected and intumescent-paint-protected 2D and 3D steel structures.
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Choe, Lisa, Selvarajah Ramesh, Xu Dai, Matthew Hoehler, and Matthew Bundy. "Experimental study on fire resistance of a full-scale composite floor assembly in a two-story steel framed building." Journal of Structural Fire Engineering, October 7, 2021. http://dx.doi.org/10.1108/jsfe-05-2021-0030.
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Purpose The purpose of this paper is to report the first of four planned fire experiments on the 9.1 × 6.1 m steel composite floor assembly as part of the two-story steel framed building constructed at the National Fire Research Laboratory. Design/methodology/approach The fire experiment was aimed to quantify the fire resistance and behavior of full-scale steel–concrete composite floor systems commonly built in the USA. The test floor assembly, designed and constructed for the 2-h fire resistance rating, was tested to failure under a natural gas fueled compartment fire and simultaneously applied mechanical loads. Findings Although the protected steel beams and girders achieved matching or superior performance compared to the prescribed limits of temperatures and displacements used in standard fire testing, the composite slab developed a central breach approximately at a half of the specified rating period. A minimum area of the shrinkage reinforcement (60 mm2/m) currently permitted in the US construction practice may be insufficient to maintain structural integrity of a full-scale composite floor system under the 2-h standard fire exposure. Originality/value This work was the first-of-kind fire experiment conducted in the USA to study the full system-level structural performance of a composite floor system subjected to compartment fire using natural gas as fuel to mimic a standard fire environment.
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"CROSS Safety Report: Fire protection of light-gauge steel frames." Structural Engineer 100, no. 6 (June 1, 2022): 14–15. http://dx.doi.org/10.56330/jpev8064.
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CROSS-UK was expanded to cover fire safety reporting following recommendations by Dame Judith Hackitt in her post-Grenfell report Building a Safer Future. This month we present a fire safety report illustrating the implications of substituting a product within a tested system without further testing or justification.
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Akotuah, Aaron O., Sabah G. Ali, Jeffrey Erochko, Xia Zhang, and George V. Hadjisophocleous. "STUDY OF THE FIRE PERFORMANCE OF HYBRID STEEL-TIMBER CONNECTIONS WITH FULL-SCALE TESTS AND FINITE ELEMENT MODELLING." Applications of Structural Fire Engineering, January 18, 2016. http://dx.doi.org/10.14311/asfe.2015.039.
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Connection design is critical in timber buildings since the connections tend to have lower strength than the structural members themselves and they tend to fail in a brittle manner. The effect of connection geometry on the fire performance of a hybrid steel-timber shear connection is investigated by full-scale testing. These tests were conducted by exposing the test specimens to the standard time-temperature curve defined by CAN/ULC-S101 (CAN/ULC-S101, 2007). Test results showed that the fire resistance of these connections depends on the load ratio, the type of connection and the relative exposure of the steel plate to fire. Finite element models of the connections under fire were constructed using ABAQUS/CAE and these were validated using the test results. These numerical model results correlate well with test results with ±8.32% variation.
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Sobhan, Khaled, Dronnadula V. Reddy, and Fernando Martinez. "Fire resistance of corroded high-strength structural concrete." Journal of Structural Fire Engineering ahead-of-print, ahead-of-print (September 17, 2020). http://dx.doi.org/10.1108/jsfe-10-2019-0033.
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Purpose The exposure of reinforced concrete structures such as high-rise residential buildings, bridges and piers to saline environments, including exposure to de-icing salts, increases their susceptibility to corrosion of the reinforcing steel. The exposure to fire can further deteriorate the structural integrity of corroded concrete structures. This combined effect of corrosion damage and fire exposure is not generally addressed in the structural concrete design codes. The synergistic combination of the effects of corrosion and fire forms the basis of this paper. Design/methodology/approach Concrete beam specimens with different strengths were prepared, moist-cured and corroded with impressed current. Later, they were “crack-scored” for corrosion evaluation, after which half were exposed to fire in a gas kiln. The fire damage was evaluated by nondestructive testing using ultrasonic pulse velocity. Next, all specimens were tested for residual flexural strength. They were then autopsied, and the level of corrosion was determined based on mass loss of the reinforcement. Findings For corroded specimens, the flexural capacity loss because of fire exposure increases as the compressive strength increases. In general, the higher the crack score, the higher the corresponding mass loss, unless some partial/segmental debonding of the reinforcement occurred. The degree of corrosion increases with decreasing compressive strength. The residual moment capacity, based on analytically determined capacities of uncorroded and nonfire-exposed beams, was significantly lower than those of uncorroded beams exposed to fire. Originality/value The combined effects of corrosion and fire on the mechanical properties of structural concrete are relatively unknown, and no guidance is available in the existing design codes to address this issue. Accordingly, the findings of the paper are expected to be valuable to both researchers and design engineers and can be regarded as the initial investigation on this topic.
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Hussain, Iqrar, Muhammad Yaqub, Mina Mortazavi, Muhammad Adeel Ehsan, and Mudasir Hussain. "Analytical and Numerical Study of Fire-Damaged Circular Concrete Columns Repaired Using Composite Confinement Techniques." Proceedings of the Institution of Civil Engineers - Structures and Buildings, May 24, 2022, 1–42. http://dx.doi.org/10.1680/jstbu.21.00017.
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This paper presents numerical and regression modeling of 21 undamaged, fire-damaged, and repaired fire-damaged reinforced circular concrete (RC) columns. The columns were exposed to three different temperatures of 300°C, 500°C, and 900°C and tested for axial residual capacity. It was found that concrete loses its strength after exposure to a temperature of 300°C or above. Fire-damaged columns were then repaired using various composite confinement techniques. Strength was regained when CFRP confinement was applied to fire-damaged columns but it increased the deformation as well and thus reduced the stiffness which is not desirable. To overcome this challenge, steel wire mesh, filled with cement sand mortar and wrapped with CFRP was employed. Further, a numerical model was developed that could precisely predict the residual capacity of these columns. The paper briefly reviewed and summarised the development of numerical techniques, including material properties, geometry, elements, loading, boundary conditions, and contact algorithm for undamaged, fire-damaged, and repaired fire-damaged columns. Moreover, analytical equations were developed using linear, multiple, and quadratic regression modeling. The results obtained using the proposed model and regression equations showed that these models offered a better alternative to the experimental testing for the prediction of the post-fire performance of damaged and repaired RC columns.
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Veenstra, Rozemarijn, Chris Noteboom, Faidra Oikonomopoulou, and Mauro Overend. "Design, Engineering and Experimental Testing of Tubular Glass Columns." Challenging Glass Conference Proceedings 8 (June 20, 2022). http://dx.doi.org/10.47982/cgc.8.410.
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This research revolves around the design, fabrication and testing of tubular glass columns, with particular focus on their redundancy and fire-safety mechanisms; moreover, addressing aspects such as: the column shape; cleaning and maintenance; end connections; geometric tolerances in the glass and demountability. Two alternative circular hollow (tube) column designs are initially developed and engineered to address these aspects, namely: the MLA (Multi Layered with Air) and the SLW (Single Layered with water). In both concepts the main load-bearing structure consists of two concentric laminated glass tubes. Thus, in order to explore the manufacturing challenges and structural potential of these concepts, the prototyping and experimental work focuses on six 300 mm long samples with 115 mm outer diameter that are laminated and fitted into customized, engineered steel end-connections. Particular attention in terms of manufacturing is paid to the lamination process and associated bubble formation, the possible fracture of the glass by internal resin-curing stresses and the interface between the glass tube and the steel end-connections. All samples are laminated with Ködistruct LG 2-PU component. Three samples are assembled using DURAN® (annealed) glass and the other three are using DURATAN® (heat-strengthened) glass. Subsequently, the six samples are tested in compression until failure to investigate the behaviour of the interlayer material, the post-fracture behaviour of the designs, the differences between annealed and heat-strengthened samples, the capacity of the glass tubes and the performance of the end connections. Initial cracks appeared between 95-160 kN (compression strength of 30-50 MPa) in the DURAN® samples and between 120-160 kN (compression strength of 37-50 MPa) in the DURATAN® samples. These loads are lower than the ones estimated by calculations; in specific, the first cracks occurred at 34-64% of the calculated load. Nevertheless, the samples are found to be robust, with a considerable load-bearing capacity beyond the first cracks, leading to a maximum nominal compression strength capacity of up to 152 MPa for the DURATAN® samples and up to 233 MPa for the DURAN® samples.
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Owens, Roger L. "Forensic Engineering - Testing Of Hostile Electrical Connections In A Residential Clothes Dryer." Journal of the National Academy of Forensic Engineers 20, no. 2 (January 1, 2003). http://dx.doi.org/10.51501/jotnafe.v20i2.620.
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A Fire Occurred In A Residence That Was Being Utilized As A Day Care Center. All Parties Involved In The Initial Investigations Into The Fire Cause Agreed That The Fire Originated In The Laundry Room In The Vicinity Of The Electric Clothes Dryer. The Plaintiffs Expert Opined That The Dryer Was Defectively Designed And Hence Caused The Fire. This Writer Was Retained By The Manufacturer Of The Dryer And Asked To Determine The Most Probable Failure Mode And To Test An Exemplar Dryer In Order To Validate Those Observations. The Ignition Point Appeared To Be At A High Resistance Electrical Connection At The Dryer Heater Box Involving Both Copper And Steel. (See Figure 1) Initial Examination Of The Clothes Dryer At The Residence Revealed That The Dryer Heater Circuitry Connection Had Been Modified. One Of The Male Prongs Had Been Removed, The Insulating Material Stripped Back And The #10 Awg Stranded Copper Wire Was Partially Inserted And Held In Place By A Common Steel Wood Screw. (See Figure 2) The Conductor Strands And The Wood Screw Appeared Heavily Heat Stressed And Appeared To Be A Viable Ignition Source. A Few Inches Away Black Electrical Tape Was Deformed By Heat But Not Fully Combusted. (See Figure 3) This Connection Was Duplicated On An Exemplar Dryer Test Stand And Under Operating Conditions Ignited Lightweight Fabrics.