Redistribution of Internal Forces in RC Beams due to Fire Action

3rd World Multidisciplinary Civil Engineering, Architecture, Urban Planning Symposium

土木建筑工程;文学

Chudyba, Krzysztof^1

Cracow University of Technology, 24 Warszawska St., Kraków

31-029, Poland^1

关键词: Continuous beams;    Fire temperatures;    Redistribution of internal force;    Reinforcing steels;    Stress redistribution;    Structural systems;    Temperature changes;    Ultimate limit state;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/471/5/052013/pdf
DOI  :  10.1088/1757-899X/471/5/052013

学科分类：土木及结构工程学

来源: IOP

【 摘 要 】

Due to the fire temperature action material properties (for RC structures - for concrete and reinforcing steel) are subjected to degradation. This results in the reduction of stiffness of cross-section of the elements and finally in redistribution of internal forces for statically indeterminate structural systems (for continuous beams and slabs, for frames). Thus it is important to take into account these effects while carrying out the fire design of such structures, because as a result of internal forces redistribution the ultimate limit state in fire situation may be achieved earlier than for analysis neglecting these effects. In the paper there is analyzed the question of stress redistribution for cross-sections of RC beam fixed at both ends subjected to the action of dead and live loads on its upper surface as well as the fire temperature acting from the other three sides of the beam. The temperature change with the time was assumed in accordance with standard fire curve (ISO 834). Analysis was carried out with the finite element method (FEM) with the application of Abaqus program. Results of analysis indicate the importance of redistribution effects for longer fire duration time (more than 90 min) and the redistribution includes the reduction in values obtained for span crosssection and increase in support one.