Influence of Concrete Cover on Fire Resistance of Reinforced Concrete Flexural Members

2004 ◽  
Vol 130 (8) ◽  
pp. 1225-1232 ◽  
Author(s):  
Xudong Shi ◽  
Teng-Hooi Tan ◽  
Kang-Hai Tan ◽  
Zhenhai Guo
2010 ◽  
Vol 452-453 ◽  
pp. 197-200 ◽  
Author(s):  
Zhen Qing Wang ◽  
Zhi Cheng Xue ◽  
Mu Qiao

For the mechanical properties of reinforced concrete under high temperature with large deterioration, the reliability of reinforced concrete beams have been largely discounted. A calculation of fire resistance based on failure probability is given by this paper. Reinforced concrete beam is usually working with cracks. Since each section with cracks has possibility of destruction, the reliability of the beam is calculated by the minimum value of n crack-sections’ resistance. The plastic zone resistance of concrete under high temperature is considered in this paper. A simple and feasible time-variant model of the resistance of reinforced concrete beams under fire and a reliability index analysis method of reinforced concrete beams under fire has been given. The action of ISO834 temperature rising curve on the reliability index of different specifications of concrete beams at different time is analyzed. The action of main parameters on the reliability index changes with time is shown. The fire resistance considers the failure probability is given. The results show that increase the reinforcement ratio and concrete cover thickness appropriately are effective measures to improve the fire resistance limit of reinforced concrete beams.


Author(s):  
Leopold Mbereyaho ◽  
Francois Twayigize ◽  
Laury Givens Musabe Ishimwe ◽  
Sandrine Mutumwinka

With the development of infrastructures in Rwanda, the roads construction has been one of busiest area, and as the country counts thousands hills the design and construction of drainage systems required a great attention. Most of road drainage channels are covered with concrete plates that are reinforced with ordinary steel bars, while others are not covered due to the high cost of reinforced concrete plates. As the majority of these  plates are only subjected to light pedestrian loads, they should be reinforced accordingly. This study was intended to check the potentials of sisal fibres from Agave Sisalana’ cactus plant which has shown good results in flexural members, as plates reinforcements. At first the quality of ordinary concrete components was checked. Then some of sisal fibres were prepared, manufactured into ropes of 10 mm diameter and then used as replacements of main steel bars in concrete plates before their tensile capacity was checked. Other pieces of sisal fibres of 5 cm length were mixed in concrete mass with different percentages of 0.5%, 1% and 1.5% of concrete volume. Test results showed that the compressive, tensile and flexural strengths for concrete with 1% of sisal fibres were more adequate for M30 concrete and therefore able of sustaining the real loads applied to the  drainage concrete cover plates. As the performance of natural sisal fibres depends on fibres treatment methods, length, and type of required concrete, further studies on the use of sisal fibres should consider those factors. Keywords: Agave sisalana, drainage channel, Reinforced Concrete, Sisal Fibres, Sisal ropes.


2016 ◽  
Vol 10 (10) ◽  
pp. 62
Author(s):  
Ahmad Salah Edeen Nassef

This paper was investigating cracks in reinforced concrete members subjected to pure bending using nonlinear damage mechanics approach. Concrete, steel and total damage variables were introduced and correlations were derived. Comparisons with different experimental and theoretical methods were executed, comparison between the proposed approach and different codes of practices were also executed. A parametric study was carried out for total damage variable considering both concrete cover and reinforcement ratio at different concrete damage variable.


2012 ◽  
Vol 166-169 ◽  
pp. 1379-1382 ◽  
Author(s):  
Dong Fu Zhao ◽  
Zuo Kai You ◽  
Dong Dong Liu

To research the temperature field distribution of concrete beams, experiments on fire resistance of 6 reinforced concrete simple-supported beams were completed. Test results indicate that: the trends of the temperature field distribution in each section of beam are the same, but the difference of the values in each section is large; the larger section of beam is, the higher temperature of beam surface and the more slowly the heat transfer to the internal of beam, which shows the increase of concrete cover thickness can improve fire resistance of beams; After the fire, the gradient of temperature field distribution is very serious in the internal of beam; the higher the temperature of the fire, the bigger damage of reinforced concrete beams is.


Author(s):  
Fidan Salihu ◽  
Meri Cvetkovska

The behavior of simply supported reinforced concrete slabs in fire conditions and the influence ofcertain parameters on their fire resistance is analysed in this paper. The influence of the slab span,concrete cover thickness and the type of reinforcement scheme are analysed. All slabs are exposedto standard fire ISO 834. The analyses are conducted by using the computer program SAFIR2016,which is based on the Finite Element Method, and the simplified procedure given in EN 1992-1-2.For the numerical analyses, two approaches are used: 2D-analysis, when the discretization isperformed with beam elements and 3D-analysis, when the discretization is performed with shellelements. The 3D-analyses are performed for a meter width strip and for the real width of the slabs.The width of the slabs is adopted to be the same with the span.


Author(s):  
Sanin Džadić

Concrete elements are practically an integral part of every construction project andbuilding. They have significantly higher fire resistance in comparison to elements madeof other construction materials. However, RC slabs are the most sensitive concreteelements to the effects of fire when compared to all the other reinforced concrete elements.Therefore, this research focuses on determining the fire resistance of RC slabs usingMethod for determining fire resistance of slabs BAS EN 1992-1-2:2017, Eurocode 2,Design of concrete structures, Part 1-2: Structural fire design (Tabulated Data) andBRANZ Technical recommendation No. 8 – Method for Fire Engineering Design ofStructural Concrete Beams and Floor Systems. A fire action to RC slabs is modeled usingstandard fire ISO 834-1 (BAS EN 1991-1-2:2015). This research considers determiningfire resistance of simply supported RC slabs of different spans and different depths withvariations of concrete cover.


2020 ◽  
Vol 24 (1) ◽  
pp. 11-16
Author(s):  
Saddam - Husein ◽  
Rudy Djamaluddin ◽  
Rita Irmawaty ◽  
Kusnadi Kusnadi

SADDAM HUSEIN. Analisa Pola Kegagalan Balok Beton Menggunakan GFRP Bar Tanpa Selimut Beton (dibimbing oleh Rudi Djamaluddin dan Rita Irmawaty) Struktur beton bertulang yang menggunakan tulangan baja pada daerah korosif, menjadi rawan terhadap kerusakan atau penurunan kekuatannya akibat korosi.Korosi pada tulangan baja merupakan salah satu faktor penyebab menurunnya kekuatan struktur beton bertulang. Salah satu material yang dikembangkan mengatasi korosi adalah penggunaan material tulangan GFRP (Glass Fiber Reinforced Polymer). Penelitian ini bertujuan untuk menganalisa kapasitas lentur dan pola kegagalan balok beton tanpa selimut dengan menggunakan material tulangan GFRP bar.   Desain penelitian merupakan eksperimental laboratorium dengan rekapitulasi sebanyak 6 sampel yang terdiri dari 2 Balok beton menggunakan tulangan baja dengan selimut beton, 2 balok beton menggunakan tulangan GFRP bar dengan selimut beton, 2 balok beton menggunakan GFRP bar tanpa selimut beton. Metode pengujian dilakukan dengan dengan pengujian lentur statik monotonik dan Analisis data menggunakan uji kondisi retak awal dan kondisi ultimit.   Hasil penelitian ini menunjukkan bahwa kapasitas lentur pada balok dengan tulangan GFRP bar lebih besar dibandingkan dengan balok tulangan baja dan mampu meningkatkan kapasitas lentur balok dalam menahan beban sebesar 39.76 %, pola kegagalan beton yang terjadi pada balok tulangan baja mengalami kegagalan lentur tekan ditandai dengan retakan yang terjadi pada sisi tertekan dan membentuk retakan tegak dengan sumbu netral beton yang tertekan, sedangkan pada balok beton tulangan GFRP tanpa selimut mengalami kegagalan keruntuhan tekan geser dengan kondisi tulangan berdeformasi (bi-linear) dengan retak miring dan secara tiba-tiba menjalar menuju sumbu netral beton yang tertekan sehingga terjadilah keruntuhan secara tiba-tiba.     SADDAM HUSEIN.Failure mode analysis of concrete Beams Using GFRP rebar Without concrete cover (supervised by Rudi Djamaluddin and Rita Irmawaty)   Reinforced concrete that uses rebar steel in corrosive areas, are prone to damage or decreased strength due to corrosion. Corrosion in the steel reinforcement is one of the factors that decreasing strength of reinforced concrete. One of the materials developed to overcome corrosion is the use of GFRP (Glass Fiber Reinforced Polymer) reinforcement material. This study aims to analyze the flexural capacity and failure mode of concrete beams without concrete cover using material GFRP bar as reinforcement.   The research design was an experimental laboratory with a recapitulation of 6 samples consisting of 2 beams using steel reinforcement with concrete cover.2 concrete beams using reinforcement GFRP bar with concrete cover, 2 beams using GFRP bars without concrete cover. The  research method uses the monotonic static flexure and analyzing the data using the initial crack condition and ultimate conditions test.   The results of the research indicate the flexural capacity of the beams with GFRP bar reinforcement is higher than steel reinforcement beams and can increase 39.76% of the flexural capacity of the beams in holding loads , the failure mode analysis occurs in steel reinforcing beam experiences compressive failure. Failure was characterized  by cracks that occur on the depressing side and form an upright crack with the neutral axis of the compressed concrete, whereas in GFRP reinforced concrete beams without concrete cover, failure of shear compression with conditions of deformed reinforcement (bi-linear) with sloping cracks and suddenly spread towards the neutral axis of the compressed concrete so that there was a sudden collapse.


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