10.19: The steel and fibre-reinforced concrete circular hollow section composite column exposed to fire

ce/papers ◽  
2017 ◽  
Vol 1 (2-3) ◽  
pp. 2678-2687 ◽  
Author(s):  
Tkalenko Illia ◽  
Tretyakov Alexey ◽  
Wald František ◽  
Novak Josef ◽  
Stefan Radek ◽  
...  
2017 ◽  
pp. 73-79
Author(s):  
Tretyakov Alexey ◽  
Tkalenko Illia ◽  
Wald František ◽  
Novak Josef ◽  
Stefan Radek ◽  
...  

Author(s):  
Frantisek Emanuel WALD ◽  
Tesfamariam Arha ◽  
Vladimir Křístek ◽  
Alexey Tretyakov ◽  
Lukas Blesak ◽  
...  

This study predicts the shear strength of steel fibre reinforced concrete (SFRC) members at elevated temperature using numerical modelling. The authors derived the stress-strain relation in the pure shear mode at ambient temperature based on a damage model calibrated at ambient and elevated temperatures. The model was validated on the special experimental arrangement for the pure shear mode of the SFRC in torsion. These results enables to determine the stress-strain diagram at elevated temperature. The shear strength of SFRC is compared with the compressive and tensile strength and used to observe reasons for experimentally observed failure model. The work is a part of comprehensive project focused on development of design models for the steel and SFRC composite columns with circular hollow section (CHS) at elevated temperature. Research includes two levels accuracy/complexity, allowing simplified or advanced approach to design following the coming changes in European standard for composite member design in fire, EN1994-1-2:2021. Experimental studies of the project include mechanical material tests of heated fibre-concrete samples in tension and compression, thermal uniform and non-uniform tests of insulated fragments of CHS and tests of full scale SFRC CHS columns in steady-state and transient-state regimes. Developing advanced FEM simulation of global mechanical behaviour of SFRC CHS columns is a multi-levelled composite mechanical and thermo-model and provide numerous numerical experiments. Together with steel material model in fire, validated FEM model of mechanical behaviour of fibre-reinforce concrete at elevated temperature is performed. Validated simplified and advanced thermal model of SFRC in CHS at elevated temperature gives temperature fields and moisture distribution inside section which depends on direction, heat flux, sizes and gives possibility to model different fire cases of full-scale columns in bending, shear, and buckling at elevated temperature. Proposed analytical and simplified FEM mechanical model of column is taking into account degradation of mechanical properties, analytical models of transfer of heat inside the column section and provides simple solutions for designers. 


2019 ◽  
Vol 26 (4) ◽  
pp. 197-208
Author(s):  
Leo Gu Li ◽  
Albert Kwok Hung Kwan

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.


2014 ◽  
Vol 5 (2) ◽  
pp. 119-125
Author(s):  
I. Kovács

The present paper of a series deals with the experimental characterisation of flexural toughness properties of structural concrete containing different volume of hooked-end steel fibre reinforcement (75 kg/m3, 150 kg/m3). Third-point flexural tests were carried out on steel fibre reinforced concrete beams having a cross-section of 80 mm × 85 mm with the span of 765 mm, hence the shear span to depth ratio was 3. Beams were sawn out of steel fibre reinforced slab elements (see Part I) in order to take into consideration the introduced privilege fibre orientation (I and II) and the position of the beam (Ba-a, Ba-b, Ba-c) before sawing (see Part I). Flexural toughness properties were determined considering different standard specifications, namely the method of the ASTM (American Standards for Testing Materials), the process of the JSCE (Japan Society of Civil Engineering), and the final proposal of Banthia and Trottier for the post cracking strength. Consequently, behaviour of steel fibre reinforced concrete was examined in bending taking into consideration different experimental parameters such as fibre content, concrete mix proportions, fibre orientation, positions of test specimens in the formwork, while experimental constants were the size of specimens, the type of fibre used and the test set-up and test arrangement.


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